Category: Air Purifier

An air purifier is only as good as the air it actually moves through a real filter. Boon Airvana pairs an H13 HEPA filter (99.95% of particles in a single pass) and activated carbon with a CADR of 380 m³/h, enough for a room of about 484 sq ft, and more than nine air changes an hour in a 12 × 12 ft bedroom.

Its AtmoScan sensor reads PM1.0, PM2.5, PM10, TVOC, eCO₂, NO₂, temperature and humidity every second, so you see the number rather than a coloured ring. Auto mode follows the live AQI, Sleep runs quietly overnight, and the Boon app works with Alexa, Google Home and Matter.

Not sure what size you need? Use the air purifier size calculator, or read how to choose an air purifier for home. You can check your city’s air on the AQI by city page.

Air Purifier or Open the Windows? What Works Better in Indian Homes

You need both, at different times. Opening windows removes carbon dioxide, humidity and cooking gases that no air purifier can; a purifier removes fine particles that open windows let in on bad days. When the outdoor AQI is Good or Satisfactory, open up. When it is Poor or worse, air the room briefly, then close the windows and run the purifier.

The Short Answer: Both, at Different Times

“Air purifier vs opening windows” sounds like a choice, but the two do different jobs. Ventilation swaps stale indoor air for outdoor air. Filtration cleans the indoor air you already have. Which one helps more at any moment depends on one thing above all: how clean the outdoor air is right now.

	Opening windows	Air purifier, room closed
Carbon dioxide	Removes it	No effect
Humidity and damp	Lowers it when outdoor air is drier	No effect
Cooking gases and smells	Clears them	Activated carbon helps with some odours; it saturates
PM2.5 and PM10 on a smoggy day	Brings more in	Removes them
PM2.5 on a clean-air day	Dilutes indoor particles	Removes them, but fresh air may be enough
Pollen in season	Brings it in	Captures airborne pollen

What Opening Windows Does That a Purifier Can’t

Every person in a closed room breathes out carbon dioxide. Gas cooktops release combustion gases, and cooking, bathing and drying clothes add moisture. None of these are particles, so a HEPA filter does not catch them. A purifier does not remove CO₂ or carbon monoxide, and it does not add oxygen: it cleans the same air, it does not refresh it. Our guide to what air purifiers cannot remove goes through the full list.

Outdoor air is roughly 420 ppm of CO₂. Around 1,000 ppm indoors is a widely used rule of thumb that a room needs more fresh air. A closed bedroom with two people overnight, or a small study used all day, can pass that comfortably. The heavy, stuffy feeling many people blame on pollution is often this, and only ventilation fixes it.

Ventilation also matters for damp. In the monsoon and in humid coastal cities, moisture trapped indoors feeds mould on walls and in cupboards. Moving air out, whether through windows or exhaust fans, is the first fix.

When Open Windows Make Indoor Air Worse

Fresh air is only fresh if the outdoor air is clean. On a day when the AQI is in the Poor, Very Poor or Severe bands, an open window is a wide channel for PM2.5 to pour in. A home purifier filters the air of one room at a time; with windows wide open, outdoor air arrives faster than the purifier can clean it, and the room’s reading drifts towards the outdoor figure.

That is why the answer changes with the season in north India. In a Delhi winter, “let in some fresh air” can mean “let in the smog”. Check your city’s live reading on our AQI by city page before you open up, rather than judging by how the sky looks.

The rule: outdoor AQI Good or Satisfactory, open the windows. Moderate, short airing only. Poor or worse, air briefly for CO₂ and humidity, then close up and purify.

Does an Air Purifier Work With Windows Open?

It still runs and still filters the air that passes through it, but its effect on the room shrinks quickly. How much depends on the gap. A window open a crack lets in a slow trickle, and a purifier sized with headroom can often keep up. A window or balcony door wide open brings in a steady stream of outdoor air, and the purifier ends up cleaning air that is replaced moments later.

So can an air purifier be used with windows open? Yes, it does no harm, and on a clean day it adds a little. But if you are running it because the outdoor air is bad, close the windows. Otherwise you are paying for electricity and filter life without getting much cleaner air.

Does an Air Purifier Need a Closed Room?

To do its job well, yes. A purifier is sized for a room, and it works best when that room’s air is not constantly mixing with the rest of the flat or with the outdoors. Close the door and the windows, and the same unit brings the reading down far faster.

Indian homes are rarely airtight, and that is fine. A few things to know:

Sliding windows leave gaps along the track and where the panels meet. They let in some air even when shut. You do not need to seal them, but on Severe days a towel along a very leaky track helps.
Mesh doors and mosquito screens keep insects out but do nothing for fine particles. A balcony door left open behind its mesh is, for PM2.5, an open door.
Gaps under doors let air move between rooms. Keeping the bedroom door shut still makes a large difference.
Placement matters more in a leaky room. Keep the purifier away from the window itself, with clear space around it; see our guide to where to place an air purifier in an Indian home.

Boon Airvana’s fresh-air alert tells you when the room needs outdoor air, and its live PM2.5 reading tells you when to close the window again.

See Boon Airvana →

Exhaust Fans in the Kitchen and Bathroom

Exhaust fans are targeted ventilation, and they are worth using even on smoggy days. In the kitchen, a chimney or exhaust fan removes cooking smoke, oil fumes and gas combustion products at the source, before they spread. No purifier in the living room can match that. Run it while you cook and for a few minutes after.

In the bathroom, the exhaust fan removes moisture after a shower, which is the main defence against bathroom mould. Run it with the bathroom door closed.

One point people miss: an exhaust fan pushes air out, so the same amount of air must come in from somewhere, usually through window gaps and from neighbouring rooms. On a bad-air day, close the bedroom door while the kitchen exhaust runs, so the replacement air is not drawn through the room with your purifier in it.

A Routine by Season

The practical answer is a routine that changes through the year.

Smog winter, north India (roughly October to February). Keep windows shut through the night and early morning. Check the AQI and air the home for about ten minutes when it dips, often in the early afternoon, to clear CO₂ and humidity. Then close up and run the purifier in occupied rooms with the doors shut. Our guide to protecting your home from winter smog has the full room-by-room routine.
Monsoon, everywhere. Outdoor particle readings are often lower when it rains, but humidity is high. Ventilate to stop damp building up, run bathroom and kitchen exhausts, and use a purifier where you notice musty smells, since HEPA captures airborne mould spores. Fix the damp itself first.
Pleasant days in southern and coastal cities. When the AQI is Good or Satisfactory, open up. Cross-ventilation does more for a stuffy room than any filter, and the purifier can rest or run on Eco.
Summer with the AC on. The room is sealed and recirculating. Run the purifier with the AC, and open a window briefly once or twice a day, ideally in the cooler hours, to bring CO₂ down.
Pollen season. If someone at home has allergies, keep bedroom windows closed on high-pollen days and air the room at times that suit them.

Where Boon Airvana Fits

The hard part of this routine is knowing when to switch. Your eyes cannot see PM2.5, and you cannot smell CO₂. Boon Airvana’s AtmoScan sensing, developed by Boon Labs over two years, reads eight parameters every second, which covers both sides of the decision.

When to ventilate: the fresh-air alert watches eCO₂, an estimated CO₂ value rather than a direct measurement, and tells you when the room needs outdoor air. Airvana does not remove CO₂ itself; it tells you when to open the window.
When to close up: live PM1.0, PM2.5 and PM10 readings show whether an open window is bringing particles in. If the number climbs after you open up, it is time to close.
Humidity and cooking: humidity readings and the cooking fume alert (TVOC) help you decide when to run the exhausts.
Auto mode raises the fan as the room’s AQI rises and eases off as it settles, so after a short airing it brings the room back down on its own.

Airvana covers rooms up to about 484 sq ft with two H13 HEPA filters, one on each side. It is ₹14,900 at the time of writing, with a 10-day money-back guarantee.

Frequently Asked Questions

Is an air purifier better than opening windows?

Neither is better all the time. Opening windows removes carbon dioxide, humidity and cooking gases, which a purifier cannot. A purifier removes PM2.5 and PM10, which open windows bring in on polluted days. When the outdoor AQI is Good or Satisfactory, ventilate. When it is Poor or worse, air briefly, then close up and purify.

Does an air purifier work with windows open?

It still filters the air passing through it, but its effect on the room drops quickly. A window open a crack lets in a slow trickle a well-sized purifier can often handle. A window wide open brings outdoor air in faster than the purifier can clean it. On bad-air days, close the windows while it runs.

Does an air purifier need a closed room?

It works much better in one. A purifier is sized for a room, and closing the door and windows stops its cleaned air from constantly mixing with the rest of the flat or the outdoors. Indian homes have gaps around sliding windows and under doors, which is fine, but keep the room as closed as practical.

Can an air purifier replace ventilation?

No. An air purifier filters particles and, with activated carbon, some odours. It does not remove carbon dioxide or carbon monoxide and does not add oxygen. Every closed room needs fresh air from time to time. Around 1,000 ppm of CO2 indoors is a widely used sign that a room needs ventilating.

Should I use the kitchen exhaust fan on high AQI days?

Yes. A chimney or exhaust fan removes cooking smoke and gas fumes at the source, which a purifier elsewhere cannot match. Run it while cooking and for a few minutes after. Because it draws replacement air from other rooms, keep the bedroom door shut so outdoor air is not pulled through the room you are purifying.

When is the best time to open windows during Delhi smog?

Check the live AQI rather than the sky. In winter, readings are often lower in the early afternoon, when the air has mixed. Open windows across the flat for about ten minutes to clear stale air and humidity, then close up and let the purifier bring the room back down. Avoid airing at night and early morning.

Know when to open up and when to close: Boon Airvana’s fresh-air alert and live PM2.5 reading cover both. ₹14,900 at the time of writing.

See Boon Airvana →

November 3, 2026

Air Purifier Side Effects: Is It Safe to Use Every Day?

For most homes, a filter-based air purifier is safe to run every day, including overnight. A purifier that only uses a fan, a pre-filter, a HEPA filter and activated carbon has very few real downsides. The genuine risks come from specific add-on technologies that can produce ozone, from filters left dirty for too long, from poor placement, and from trusting the purifier to fix problems it cannot touch.

Is an Air Purifier Harmful? The Short Answer

Most “air purifier side effects” people search for trace back to one of five causes. It helps to separate them, because the fix for each is different:

Cause	What you might notice	What to do
Ozone-producing technology	Sharp, chlorine-like smell; throat or chest irritation	Switch off the ioniser or plasma feature, or avoid that type of unit
Dirty or overdue filters	Musty or stale smell, weaker airflow, the room takes longer to clear	Clean the pre-filter, change the main filter when due
Placement	Dry eyes or throat from a draught on your face at night	Point the outlet away from the bed
Noise	Lighter, broken sleep	Use a sleep mode or a lower speed at night
False security	Stuffy, heavy-headed mornings in a sealed room	Keep ventilating; a purifier does not supply fresh air

None of these comes from the act of filtering air. A fan pulling air through a fibre filter and a carbon bed adds nothing to the room; it only takes particles and some gases out.

Ozone: The One Real Chemical Risk

Ozone is a reactive gas. High up in the atmosphere it shields us from ultraviolet light, but at ground level, in the air you breathe, it irritates the airways and can set off coughing, a scratchy throat and chest tightness. People with asthma tend to feel it first.

Some air-cleaning devices make ozone, either on purpose or as a by-product:

Ozone generators are sold as air “fresheners” or “sterilisers” and produce ozone deliberately. These are not appropriate for rooms where people or pets are present.
Some ionisers charge particles with a high voltage so they stick to walls and surfaces. That high-voltage discharge can produce ozone as a side effect.
Some plasma-type units work on a similar electrical principle and can produce ozone too.

If your purifier has an ioniser, “anion” or plasma button, you can usually turn that feature off and keep the filtration running. A clean, sharp smell like a photocopier or a swimming pool near the unit is a sign to switch it off. Our comparison of HEPA vs ioniser vs UV air purifiers explains how each technology works and where it falls short. The point here is simple: ozone is a property of particular technologies, not of air purifiers as a category.

Headaches, Dry Throat, Dry Eyes and Cough

Can an air purifier cause headaches? A HEPA and carbon purifier itself has no mechanism for causing one. When people link the two, the usual culprits are ozone from an ioniser, a room sealed for hours so carbon dioxide and stale air build up, or noise that disturbed sleep.

Can it cause a dry throat, dry eyes or a sore throat? An air purifier does not dry the air. It does not remove water vapour, so the humidity in the room stays where it was. What it can do is blow a steady stream of air at your face if it sits close to the bed with the outlet pointed at you, and moving air across your eyes and mouth all night can leave them feeling dry. Turn the unit so the outflow goes across the room, not over the pillow. If the air itself is dry, the cause is the season or a room heater; a purifier will neither cause nor fix that.

Can it make you cough or make allergies worse? Not when it is clean and filter-only. Coughing near a unit points to ozone, a dirty filter blowing stale air, or dust released while cleaning the pre-filter indoors. If your throat and eyes burn mainly on smoggy days, see our guide on throat irritation and burning eyes in smog, which covers the pollution side.

Dirty Filters and HEPA Side Effects

A HEPA filter is a dense mat of fine fibres. It does not release chemicals, and a sealed, intact filter does not have side effects of its own. The trouble starts when filters are kept far past their useful life:

Smell. A loaded filter, especially in a humid monsoon room, can start to smell musty. Activated carbon also fills up over time, and once saturated it stops taking up odours.
Weaker cleaning. A clogged pre-filter or HEPA layer restricts airflow, so the room takes longer to clean and the fan works harder.
Dust on handling. A used filter is full of everything it caught. Wash or tap out the pre-filter on a balcony or outdoors, not over your bed, and bag the old main filter before binning it.

Our air purifier maintenance and filter care guide covers how often to clean and what a healthy filter looks like.

Boon Airvana uses a washable pre-filter, two H13 HEPA filters and activated carbon, and reminds you when the pre-filter needs cleaning or the filter needs changing.

See Boon Airvana →

Radiation, Cancer and Fire: What Is True

Does an air purifier emit radiation? Not in the sense most people fear. A purifier is a fan, filters and a small circuit board. Like a table fan or a phone charger, it gives off the weak electromagnetic fields every powered appliance does, and connected models use the same kind of low-power radio as a phone or a home router. It does not emit X-rays or anything nuclear.

Can an air purifier cause cancer? Nothing in a fan, a HEPA filter or an activated carbon bed is known to cause cancer. The health concern with some air cleaners is ozone, covered above, which is an airway irritant.

Can an air purifier catch fire? Any electrical appliance can fail, and the same household basics apply:

Plug it directly into a wall socket where you can, rather than into an overloaded extension board.
Keep the air inlets and outlet clear of curtains, clothes and walls, so the motor is not starved of air.
Do not run it with a damaged cable, and keep it away from water and from heaters.
If you smell burning or hear a grinding noise, switch it off at the socket and contact the brand’s service team.

Is It Safe for Babies and Asthma Patients?

Babies. A filter-only purifier is commonly used in nurseries. Keep it out of reach, a little away from the cot, with the airflow not blowing on the baby, use a child lock if it has one, and avoid ionisers and ozone generators entirely in a baby’s room. Our guide to an air purifier for a baby’s room covers sizing and placement in more detail.

Asthma. Many people with asthma use a HEPA purifier to lower particle levels at home. The one thing to avoid is any device that can produce ozone, since ozone irritates the airways. A purifier lowers exposure to particles; it does not treat asthma, and it does not replace the medicines and plan your doctor has given you. More in our guide on choosing an air purifier for asthma.

When to see a doctor. If coughing, wheezing, headaches, a sore throat or burning eyes persist for more than a few days, get worse, or come with breathlessness or chest pain, see a doctor. Do not assume the purifier, or the pollution, is the whole story.

The Quiet Risk: False Security

The most common way an air purifier “harms” a household has nothing to do with the machine. It is the habit it encourages: windows shut for days, bedroom doors closed, and a sense that the air is now taken care of. A purifier removes particles and, through carbon, some odours and gases. It does not remove carbon dioxide or carbon monoxide, and it does not add oxygen.

In one line: run the purifier, but keep airing the room in short bursts when the outdoor air allows, and never use a purifier as a reason to run an angeethi, heater or generator in a closed room.

How Boon Airvana Filters the Air

Here is what Boon Airvana does to the air, so you can judge it against everything above. Air is drawn in from both sides and passes through a washable pre-filter mesh that catches large dust and hair, then through two H13 HEPA filters, one on each side, which capture 99.95% of particles in a single pass. Activated carbon takes up odours and gases, and the filter carries an anti-bacterial coating. Airvana has no ioniser and produces no ozone: everything it does to the air is mechanical filtration and carbon.

Its AtmoScan sensing reads eight parameters every second, including an estimated CO₂ value that drives a fresh-air alert when the room needs outdoor air, which addresses the false-security risk directly. Clean pre-filter and change filter reminders follow the air the unit has actually handled, not a fixed calendar. Sleep mode runs it quietly for the night, a child lock stops small hands changing settings, and continuous self-diagnostics watch the sensors, filters and motor. Airvana is ₹14,900 at the time of writing.

Frequently Asked Questions

Is it safe to sleep with an air purifier on all night?

Yes, for a filter-based purifier with no ozone-producing feature. Use a sleep mode or low speed so noise does not disturb you, and point the airflow across the room rather than at your face, which can leave eyes and throat feeling dry. Air the room before bed and leave the door ajar if you can, since a purifier does not supply fresh air.

Can an air purifier cause headaches?

A HEPA and carbon purifier has no mechanism for causing headaches. When people notice one, common causes are ozone from an ioniser or plasma feature, a room kept sealed so stale air and carbon dioxide build up, or disturbed sleep from noise. Switch off any ioniser, ventilate regularly, and see a doctor if headaches keep returning.

Does an air purifier dry the air or cause a dry throat?

No. An air purifier does not remove moisture, so room humidity stays the same. A dry throat or dry eyes usually come from a draught blowing on your face all night, a room heater, or dry seasonal air. Turn the outlet away from the bed. If the dryness or soreness lasts for days, see a doctor.

What are the side effects of an ionizer air purifier?

Some ionisers produce ozone as a by-product of the high voltage they use, and ozone irritates the airways, which can cause coughing, throat irritation or chest tightness, especially in people with asthma. Charged particles can also stick to walls and leave dark marks. If your purifier has an ioniser button, you can usually switch it off and keep the filters working.

Is an air purifier safe for babies?

A filter-only purifier with no ioniser or ozone feature is widely used in nurseries. Keep it out of reach and a little away from the cot, make sure the airflow does not blow on the baby, use a child lock if available and keep the filters clean. Speak to your paediatrician about any breathing symptoms rather than relying on the purifier.

Does an air purifier emit harmful radiation?

No. An air purifier is a fan, filters and a small circuit board. It gives off the same weak electromagnetic fields as any household appliance, and connected models use low-power radio similar to a phone or router. It does not produce X-rays or any nuclear radiation. Basic electrical safety, such as using a wall socket, matters more.

Boon Airvana has no ioniser and produces no ozone: a pre-filter, two H13 HEPA filters and activated carbon, with a fresh-air alert. ₹14,900 at the time of writing.

See Boon Airvana →

November 3, 2026

Air Purifier Light Colours: What Red, Orange, Yellow and Green Mean

On most air purifiers, the coloured light shows the air quality the purifier’s sensor is reading in your room right now. Colours usually follow AQI bands: green for clean air, yellow for moderate, orange for poor and red for very poor. A red light right after cooking or lighting agarbatti is normal and should fade as the purifier works, but brands use their own colour schemes, so check your manual.

What the Coloured Light Is Measuring

Inside most purifiers sits a particle sensor. On better units it is a laser sensor that counts fine particles; on cheaper ones it is often a simpler infrared dust sensor. The purifier turns that reading into an air-quality level and lights a ring, bar or dot in the matching colour. On many models the same reading also drives Auto mode, so a change of colour usually comes with a change of fan speed.

Three things to keep in mind:

It is your room, not your city. The light reflects the air near the purifier, which can be very different from the outdoor AQI on your phone.
It is usually about particles. On most purifiers the colour is driven by PM2.5, sometimes PM10 as well. Gases, smells and stuffiness often do not change it. Our explainer on PM2.5 vs PM10 covers what those sizes mean.
Not every light is about air quality. Many purifiers also have a separate filter or service light, and on some models that warning is red too.

Two other behaviours confuse people. First, many purifiers dim the ring or switch it off in sleep mode, so a dark unit at night may still be running. Second, a light that flashes or blinks rather than glowing steadily is often a reminder or a fault code, not an air-quality reading. Both are model-specific, so the manual is the place to check before assuming the air or the purifier has a problem.

The AQI Colour Scale Most Purifiers Follow

In India, the reference point is the CPCB National Air Quality Index. It has six bands, each with a standard colour. Many purifiers sold here follow this scale closely or simplify it into four or five colours.

AQI	Band	Standard colour
0 to 50	Good	Dark green
51 to 100	Satisfactory	Light green
101 to 200	Moderate	Yellow
201 to 300	Poor	Orange
301 to 400	Very Poor	Red
401 to 500	Severe	Maroon

Brands differ. Some use blue instead of green for clean air, some merge bands, and some set their own thresholds based on a PM2.5 value rather than the full AQI. So “yellow” on one purifier may not mean exactly the same as “yellow” on another. The user manual will have the brand’s own chart. For what level is reasonable to aim for indoors, see our guide on a safe indoor AQI level.

What to Do at Each Colour

Green: the room is clean. If the purifier is on Auto, it should already have dropped to a low speed. Nothing to do.
Yellow: moderate. Common on an ordinary day in many Indian cities. Keep windows mostly shut on a polluted day, let it run, and expect it to return to green.
Orange: poor. Something is adding particles: cooking, incense, dusting, a window open to traffic or smog. Find the source, close the room and let the purifier run on Auto or a higher speed.
Red or maroon: very poor or severe. Close windows and doors, stop any burning indoors, and give the purifier time. If people in the room have asthma or other breathing conditions, keep them in the cleanest room until it drops.

If a colour stays high for hours with the room closed, the purifier may be too small for the space, or air may be leaking in through gaps. Check your outdoor reading on AQI by city to see whether the whole city is having a bad day.

Boon Airvana shows live readings on a full-colour display, including an AQI graph, so you can see how fast the room is recovering, not just which colour it is.

See Boon Airvana →

Why Is My Air Purifier Light Red?

Most of the time, a red light means the sensor is reading a lot of particles, and the reason is close by:

Cooking. A tadka, frying or a dosa tawa sends a burst of fine particles through the home, especially in open kitchens.
Agarbatti, dhoop, diyas and mosquito coils. Burning anything produces very fine smoke. Our guide on agarbatti and dhoop smoke indoors explains why even one stick can push readings up.
Sweeping, dusting and shaking out bedding. These stir settled dust back into the air.
Sprays. Room fresheners, deodorants and some cleaning sprays are droplets the sensor can count as particles.
An open window on a smoggy day, or a road-facing room at rush hour.
Steam and very humid air. Particles take up moisture and swell, and steam from a bathroom or a pressure cooker can push some sensors up for a while.

In all these cases, red right after the event is normal. A purifier doing its job should bring the colour back down as it cleans; on Auto, the fan speeds up first.

When the Red Light Never Changes

A light that stays red for days, even with the room closed and nothing burning, points to a problem with the purifier or the room rather than the air:

Check whether it is a filter alert. On some models a red light means “change the filter”, not “bad air”. The manual will tell you which.
Clean the sensor opening. Dust can collect in the small inlet of a particle sensor and make it read high. Follow the manual; many sensors have a small cover you can open and wipe gently with a dry cotton bud.
Clean the pre-filter and check the main filter. A clogged filter means less clean air, so readings stay up. Our air purifier maintenance and filter care guide covers the routine.
Move the purifier. Right next to the kitchen door, a window or a humid bathroom, the sensor sees the worst air in the home.
Compare with outdoor AQI. If the city is in the Severe band and the home is leaky, the purifier may genuinely be fighting a losing battle.

If none of this helps, contact the brand’s service team; the sensor may be faulty.

Colour Ring vs Numeric Display

A colour-only light tells you roughly where the air sits. A numeric display, such as a PM2.5 reading in µg/m³ or an AQI figure, tells you much more:

Progress within a band. Red covers a wide range. A number shows whether you are at the top of it or nearly out.
Speed of recovery. Watching the number fall after cooking shows whether the purifier is keeping up with the room.
Comparison with standards. You can set your indoor PM2.5 against the Indian 24-hour standard of 60 µg/m³ and the WHO 24-hour guideline of 15 µg/m³.
Which pollutant. Displays that show PM1.0, PM2.5 and PM10 separately help you tell smoke from dust.

In one line: the colour tells you whether to act; the number tells you whether what you did is working.

How Boon Airvana Shows Air Quality

Boon Airvana uses a full-colour display rather than a single light. You choose between watch faces: full metrics, AQI only, an AQI graph, and a High AQI alert screen that comes up when the air gets bad. Live readings come from AtmoScan sensing, developed by Boon Labs over two years, which reads eight parameters every second: PM1.0, PM2.5 and PM10 by laser, plus TVOC, eCO₂ (an estimated value), NO₂, temperature and humidity.

Separate alerts tell you why the air changed and what to do: a cooking fume alert, a traffic pollution alert, an allergy alert, a fresh-air alert, and reminders to clean the pre-filter or change the filter. The Boon app adds charts, trends and a diagnostics report, and continuous self-diagnostics check the sensors, filters and motor. Airvana is ₹14,900 at the time of writing.

Frequently Asked Questions

Why is my air purifier light red?

On most purifiers, a red light means the sensor is reading very poor air near the unit, usually from cooking, agarbatti, dusting, sprays or an open window on a smoggy day. It should fade as the purifier cleans. On some models red is instead a filter-change alert, so check the manual if it stays red with no obvious cause.

What does a yellow light on an air purifier mean?

Yellow usually means moderate air quality, in line with the CPCB AQI band of 101 to 200. It is common on ordinary days in many Indian cities. Keep windows mostly closed on polluted days and let the purifier run; it should move towards green. Brands set their own thresholds, so check the manual for your model.

What colour should my air purifier light be?

Ideally green, meaning the sensor reads good or satisfactory air. Most of the day in a closed room with the purifier running, that is what you should see. Short spells of yellow, orange or red after cooking or incense are normal. If it rarely reaches green, the purifier may be undersized or air may be leaking in.

Why does my air purifier light stay red all the time?

If the light stays red for days with the room closed and nothing burning, check whether it is a filter alert, clean the particle sensor opening as the manual describes, clean the pre-filter and check the main filter, and move the unit away from kitchens or humid bathrooms. If it still stays red, contact the brand’s service team.

Is an air purifier with a PM2.5 display better?

A numeric PM2.5 display tells you more than a colour light. You can see where you sit within a band, how quickly the room recovers after cooking, and how your indoor air compares with the Indian 24-hour standard of 60 µg/m³ or the WHO guideline of 15 µg/m³. A colour light only tells you roughly when to act.

Do all air purifiers use the same light colours?

No. Many follow the CPCB AQI colour scale, from dark green for Good through yellow and orange to red and maroon for Very Poor and Severe, but some brands use blue for clean air, merge bands or set their own PM2.5 thresholds. The manual for your model will have its own colour chart.

Get live readings instead of guessing from a colour: Boon Airvana’s full-colour display shows full metrics, AQI and an AQI graph. ₹14,900 at the time of writing.

See Boon Airvana →

November 3, 2026

Does an Air Purifier Cool the Room? 8 Common Myths, Answered

No, an air purifier does not cool the room. It moves air, and moving air on your skin feels cooler, but the room’s temperature does not drop. It is not an AC, a cooler or a substitute for a fan, and it does not add oxygen. What it does is clean the air in a closed room by pulling it through filters, over and over.

Below are the eight myths we hear most from first-time buyers, each with a short, honest answer and a link to the deeper guide where one exists.

Myths 1 and 2: Cooling and Fans

Myth 1: An air purifier cools the room or blows cold air

An air purifier has no compressor, no cooling coil and no water pad, so it has no way to take heat out of a room. The air coming out of it is at room temperature. It can feel cool if you sit in its airflow, for the same reason a breeze feels cool: moving air carries heat and moisture away from your skin faster. A thermometer in the room would not move. The motor even adds a small amount of heat, as every running appliance does, though not enough to notice.

Myth 2: An air purifier can work as a fan

Only in a very limited way. A purifier’s fan is designed to push air through dense filters and circulate it around the room, not to throw a wide, strong breeze at people. On its top speed you may feel a gentle draught nearby, but it will not replace a ceiling or pedestal fan on a hot day. Running it flat out just to feel a breeze also adds noise and uses up filter life faster than the air needs. Keep both: the fan for comfort, the purifier for clean air.

The reverse myth exists too: that a fan with a filter sheet taped to it, or a pedestal fan near an open window, does a purifier’s job. A thin sheet catches some coarse dust, but fine PM2.5 needs a sealed, dense HEPA filter and enough airflow through it to clean the whole room.

Myth 3: It Is a Kind of AC or Cooler

An AC cools and dries the air and recirculates it, and its basic mesh filter stops coarse dust to protect the coil, not fine PM2.5. A desert cooler cools by evaporating water and pulls in outdoor air, pollution included. An air purifier only cleans. They are three different appliances, and on a smoggy summer evening many homes run the AC and the purifier together with the windows shut. Our air purifier vs AC guide compares the two in detail, including whether you need both.

Myth 4: It Gives You More Oxygen

An air purifier does not give, make or increase oxygen, and it does not convert CO₂ into oxygen. No filter in a home purifier can do either. HEPA catches particles and activated carbon takes up some odours and gases; oxygen and carbon dioxide pass straight through both. If a closed room feels stuffy, the fix is fresh outdoor air from a window or door, timed for when the outdoor air is cleaner. Our guide to what air purifiers cannot remove covers CO₂, carbon monoxide and the other things a purifier will not fix.

The honest split: a purifier takes particles out of the air. It does not add anything to it: not oxygen, not coolness, not moisture.

Myth 5: It Works Fine With Windows Open

This one gets the logic backwards. A purifier cleans the same body of air again and again. With a window wide open on a polluted day, fresh outdoor air keeps replacing the cleaned air, and the purifier cannot keep up. So yes, for it to do its job, the room should be closed while it runs. That does not mean sealed for days: air the room in short bursts when the outdoor reading is lower, then shut up and let the purifier bring the particles back down.

Myth 6: It Must Sit in the Middle of the Room

It does not need to be in the middle. What matters is that air can reach the inlets and leave the outlet freely: keep it a little away from walls, curtains and furniture, not tucked in a corner behind the sofa or inside a cabinet. Near where you sit or sleep is usually better than across the room, as long as the outflow is not blowing on your face.

Does it work with a ceiling fan on? Yes. A ceiling fan mixes the room’s air, which helps carry polluted air from the corners to the purifier. It does not “blow the pollution away”; it only stirs it around, so the purifier still does the cleaning. Our guide on where to place an air purifier in an Indian home covers bedrooms, living rooms and spots near ACs.

Myths 7 and 8: Water and Size

Myth 7: An air purifier needs water

A filter-based air purifier does not use water at all. There is no tank to fill. The confusion comes from humidifiers, desert coolers and a few “water-wash” air cleaners that look similar. The only water involved in a purifier like Airvana is when you rinse its washable pre-filter, which should be fully dry before it goes back in.

Myth 8: A purifier can be too big for a room

A bigger purifier in a smaller room is not a problem. It simply cleans the room faster and can run on a lower, quieter speed, which also tends to be easier on the filters. The real mistake is the opposite: a purifier too small for the room, running flat out and still not keeping up. The air purifier size calculator works out what size your room needs.

Should it stay on 24/7? In smog season, in polluted cities, running it whenever you are in the room, and through the night, makes sense, and an Auto mode that slows down when the air is clean keeps that sensible. Our guide on how long to run an air purifier explains how long to run it and when it is fine to switch off.

Boon Airvana runs on Auto, so the fan follows the real-time AQI: faster when the air gets worse, slower once the room is clean.

See Boon Airvana →

All 8 Myths at a Glance

Myth	The truth
1. It cools the room	Moving air feels cooler; the temperature does not drop.
2. It can replace a fan	Its airflow is for circulation through filters, not a cooling breeze.
3. It is a kind of AC or cooler	It only cleans. An AC cools; a cooler cools with water and outdoor air.
4. It gives more oxygen	It adds no oxygen and does not remove CO₂. Ventilate for that.
5. It works with windows open	It needs a closed room to keep up; air in short bursts.
6. It must be in the middle	Anywhere with clear airflow; near where you spend time is good.
7. It needs water	Filter purifiers use no water. Only the pre-filter gets rinsed.
8. It can be too big	Bigger is fine and runs quieter. Too small is the real problem.

What Boon Airvana Does and Does Not Do

Boon Airvana is 1 air purifier, 2 H13 HEPA filters and 8 sensors. It draws air in from both sides through a washable pre-filter, two H13 HEPA filters and activated carbon. It does not cool the room, it does not add oxygen, and it does not need water.

What it adds is information. Its AtmoScan sensing reads eight parameters every second, including temperature and humidity, so you can see that the room’s temperature has not changed, and an estimated CO₂ reading that triggers a fresh-air alert when the room needs a window opened. Auto, Sleep and Eco modes, four fan speeds and a timer cover the “should it run all day” question without constant fiddling. Coverage is up to about 484 sq ft, and Airvana is ₹14,900 at the time of writing.

Frequently Asked Questions

Does an air purifier make the room colder?

No. An air purifier has no compressor, cooling coil or water pad, so it cannot lower the room’s temperature. The air comes out at room temperature. Sitting in its airflow can feel slightly cooler because moving air carries heat away from your skin, but a thermometer would not change. For cooling, use a fan, cooler or AC alongside the purifier.

Does an air purifier increase oxygen in a room?

No. Air purifiers do not produce oxygen and do not convert carbon dioxide into oxygen. HEPA filters catch particles and activated carbon takes up some odours and gases, but oxygen and carbon dioxide pass straight through. If a room feels stuffy, open a window or door for a few minutes when the outdoor air is cleaner.

Can I use an air purifier instead of a fan?

Not really. A purifier’s fan is built to push air through dense filters and circulate it around the room, not to create a strong cooling breeze. You may feel a gentle draught close to it on high speed, but it will not keep you cool on a hot day. Use a fan for comfort and the purifier for clean air.

Does an air purifier work with the ceiling fan on?

Yes. A ceiling fan mixes the air in the room, which helps bring polluted air from corners towards the purifier. The fan does not remove pollution itself, it only stirs it, so the purifier still does the cleaning. Keep the purifier where its inlets and outlet have clear space, a little away from walls and curtains.

Does an air purifier need a closed room to work?

Yes, mostly. A purifier cleans the same air repeatedly, so an open window on a polluted day keeps bringing dirty air in faster than it can clean. Close windows while it runs, but do not seal the room for days: air it in short bursts when outdoor pollution is lower, then close up again.

Is it OK to run an air purifier 24 hours a day?

Yes, in polluted cities and during smog season, running it whenever the room is in use, including overnight, makes sense. An Auto mode that slows the fan when the air is clean keeps noise and filter use down. Keep cleaning the pre-filter and change the main filter when the purifier says it is due.

Boon Airvana does not cool or add oxygen. It cleans the air through two H13 HEPA filters and shows you what is in it, every second. ₹14,900 at the time of writing.

See Boon Airvana →

November 3, 2026

Air Purifier Not Working? A Fix-It Guide Before You Call Service

Most air purifiers that seem not to be working have nothing wrong with the motor or electronics. The usual culprits are an overdue or clogged filter, plastic wrap left on a new filter, a filter seated the wrong way, a room that is too large or has a window open, or a mode or timer doing exactly what it was set to do. Work through the checks below first; stop and call service straight away if you see sparks, smell burning or the unit has got wet.

Five Checks Before Anything Else

Power. Try another socket, check the plug and adaptor are fully in, and check the switch on the extension board. Some units have a safety switch that cuts power if the back cover or filter door is not closed properly.
Filter packaging. New filters, including the ones shipped inside a new purifier, usually come sealed in plastic. If the wrap is still on, almost no air gets through.
Filter seating. A filter put in backwards or not pushed fully home leaves gaps for air to bypass it, and can trip the door switch.
Pre-filter. A mesh coated in dust and hair chokes airflow. Wash it if it is washable and let it dry fully before refitting.
Mode and timer. Check whether sleep mode, an eco mode, a timer or a schedule in the app is set. These change or stop the fan on purpose.

Symptom by Symptom: What to Check

Symptom	Likely causes	What to try
Won’t turn on	Socket, plug, door or filter not closed, child lock	Another socket; reseat filter and cover; check child lock
AQI not dropping	Window open, room too big, overdue filter, wrap on filter	Close up, check room size, check filter status
Reading stuck high or low	Dusty sensor inlet, humidity, placement	Clean the inlet as the manual says; move the unit
Loud or rattling	High fan speed, uneven floor, loose filter, debris	Lower speed, level surface, reseat filter
Bad smell from the unit	Saturated carbon, damp or greasy filter	Wash pre-filter, replace filter if due
Turns off by itself	Timer, eco mode, schedule, loose plug	Check settings and app schedules
App not connecting	Wi-Fi band, router distance, app permissions	Restart router and unit, move closer, re-pair

AQI Not Dropping? Room, Windows and Filters

This is the most common complaint, and usually the room, not the purifier, is to blame.

Open windows and doors. A purifier cannot clean the outdoors. On a smoggy day, even a small gap lets PM2.5 in faster than any home unit can remove it. Close up and give it time.
Room too big. A unit sized for a bedroom running in an open living-dining space will run hard and barely move the number. Check your room against the air purifier size calculator.
Active source. Cooking, agarbatti, a mosquito coil or someone sweeping keeps pushing particles up while the purifier works.
Placement. A unit wedged into a corner or behind a sofa recirculates the same pocket of air. Our guide on where to place an air purifier covers clearance.
Filter overdue. A loaded filter moves less air. If the filter alert has been on for weeks, that is your answer.

If the display reading seems stuck, check whether the sensor inlet is dusty and clean it only as the manual describes. In very humid air, laser particle sensors can read a little high, which is physics, not a fault.

Boon Airvana reminds you when to clean the pre-filter and change the filter, and runs continuous self-diagnostics on its sensors, filters and motor.

See Boon Airvana →

Noisy or Smells Bad: What the Unit Is Telling You

Noise. Every purifier is louder at high speed; in Auto mode it will speed up when the air worsens, which can sound like a fault at 9 p.m. when someone starts frying. Real problems sound different:

Rattling or buzzing: a filter or cover not seated, or the unit on an uneven floor.
Whistling: air squeezing past a gap, often a filter not pushed fully in, or a choked pre-filter.
Grinding or scraping: something touching the fan. Switch off, unplug and check for debris. If it continues, call service.

Bad smell from the purifier. A musty or sour smell usually means a filter that got damp, a pre-filter clogged with greasy dust, or a carbon layer that is saturated and has nothing left to give. Wash the pre-filter, keep the unit away from the stove and bathroom steam, and replace the main filter if it is due. Our air purifier maintenance and filter care guide covers cleaning step by step. A burning or hot plastic smell is different: see the last section.

Turns Off on Its Own, or the Light Stays Red

Switching off. Before assuming a fault, check for a timer, a schedule in the app, or an eco mode. Eco modes on many purifiers deliberately switch the fan off once the air is clean and start again when the AQI rises. That is the feature working. If none of these is set and it cuts out at random, check the plug and socket for looseness and heat, and then call service.

Light red always. On most purifiers a red indicator means one of two things: the air quality reading is poor, or a filter alert is on. Check the manual or app to see which. If it is the air reading, see the AQI section above. If it is the filter, clean or replace as prompted and reset the alert as the manual describes. A red light that never changes, even after a filter change and a clean room, points to a sensor issue for service to check.

App not connecting. Restart the router and the purifier, keep the purifier within good Wi-Fi range for pairing, and check the app’s permissions on your phone. Our guide to smart purifier apps, Alexa and Google Home covers setup, schedules and voice assistants.

When to Stop and Call Service

Some symptoms are not for home fixes. Switch off at the wall, unplug, and contact the brand’s service team if you notice:

A burning, electrical or hot plastic smell from the unit.
Sparks, smoke, crackling, or a plug or socket that is hot to touch.
Water spilled into it, or the unit has been in a flooded or very wet room.
Grinding from the fan that continues after you have checked for debris.
Repeated error messages or a fault that returns after a reset.

Safe to do yourself: sockets, settings, filters and the pre-filter. Not safe: opening the casing, the motor or the electronics. That is service work.

When you search for air purifier repair near me, local repair shops can rarely get genuine filters or sensor parts, and opening the unit may affect the warranty. Start with the brand’s own service channel and keep your invoice handy. Before you call, note the model, when the problem started, what the display or app shows, and which of the checks above you have already tried. That turns a vague “it’s not working” into a quick diagnosis, and often a fix over the phone.

How Boon Airvana Helps You Diagnose

Boon Airvana is built to tell you what is going on before you have to guess. It sends clean pre-filter and change filter alerts, based on the air it has actually handled rather than a fixed calendar. Its continuous self-diagnostics watch the sensors, filters and motor, and the Boon app shows a diagnostics report you can share with service. The pre-filter is washable.

Two settings explain most “it stopped by itself” calls. Eco mode cycles the fan off and on deliberately as the AQI settles or rises, and the timer switches it off when it runs out. A child lock can make the buttons seem dead. If something does need attention, installation and service are by Boon’s own team; reach them through the Boon contact page. Airvana is ₹14,900 at the time of writing.

Frequently Asked Questions

Why is my air purifier not working?

Most often the filter is overdue or clogged, the plastic wrap is still on a new filter, the filter is seated wrongly, or a window is open. Also check the socket, the child lock, and whether a timer, schedule or eco mode is switching it off. Call service if you smell burning, see sparks or the unit has got wet.

Why is the AQI not dropping with my air purifier on?

Usually the room is open to outdoor air, too large for the purifier, or something indoors such as cooking or agarbatti is still producing particles. An overdue filter or one still in its plastic wrap also slows it down. Close windows and doors, check the room size and filter status, and give it time.

Why does my air purifier smell bad?

A musty or sour smell usually means a damp or greasy filter, a clogged pre-filter, or a saturated carbon layer. Wash the pre-filter, keep the unit away from steam and the stove, and replace the main filter if it is due. A burning or hot plastic smell is different: switch off, unplug and contact service.

Why does my air purifier keep turning off by itself?

Check for a timer, an app schedule or an eco mode first. Many eco modes switch the fan off once the air is clean and start it again when the AQI rises, which is deliberate. If none of these is set, check the plug and socket for looseness or heat, and contact the brand’s service team if it continues.

Why is the light on my air purifier always red?

On most purifiers a red light means either poor air quality or a filter alert. Check the manual or app to see which. Close windows and remove indoor sources if it is the air reading; clean or replace the filter and reset the alert if it is the filter. If it stays red after both, ask service to check the sensor.

Should I get my air purifier repaired locally?

Start with the brand’s own service team. Local shops rarely have genuine filters or sensor parts, and opening the casing may affect the warranty. Do the safe checks yourself first: socket, settings, filter wrap, filter seating and the pre-filter. Leave the motor and electronics to service.

Boon Airvana tells you when to clean or change filters, runs self-diagnostics and is serviced by Boon’s own team. ₹14,900 at the time of writing.

See Boon Airvana →

November 3, 2026

Can an Air Purifier Remove Bad Smells? Toilet, Cooking, Smoke and Damp

An air purifier can reduce some bad smells, but only if it has activated carbon, and only partly. The HEPA filter that catches dust and smoke particles does nothing for most odours, because smells are gas molecules, not particles. For a toilet, urine, cooking or damp smell, fixing the source and running an exhaust fan matter far more than any purifier.

Can an Air Purifier Remove Bad Smells?

Partly, and it depends on the smell. Here is the honest split:

Smoke smell: a purifier helps more here than anywhere else. HEPA catches the smoke particles and carbon takes up some of the smelly gases that travel with them.
Food smells and cooking smell: carbon reduces what drifts into the next room, but a chimney or exhaust at the stove does the real work.
Bathroom smell, toilet smell and urine smell: the source is usually a drain, a dry trap, a wet floor or a soaked mat. A purifier in the corridor will not out-run it.
Musty or damp smell: it comes from mould growing on a wet wall or inside a cupboard. Carbon may dull it; drying the damp ends it.

So, does an air purifier make a room smell better? It can make a room smell more neutral, by taking out smoke and some odour gases. It does not add a pleasant smell, and it is not a substitute for cleaning.

HEPA vs Activated Carbon: Which Part Handles Smell

A typical purifier has layers that do different jobs. Knowing which one handles smell tells you what to look for.

Layer	What it catches	Does it help with smell?
Pre-filter	Hair, lint, large dust	No, apart from trapping smelly pet hair
HEPA	Fine particles: smoke, dust, pollen	Only for the particle part of smoke
Activated carbon	Odour molecules and some gases	Yes, partly, until it saturates

Activated carbon is charcoal treated to be full of tiny pores. Odour molecules stick to its huge internal surface, a process called adsorption. Two limits follow from that. First, it is not a fix for every gas; it holds some better than others. Second, it saturates. Once the pores are full, it stops taking up odours, and a heavy daily load, such as a smoker in the house or frying every evening, fills it sooner. More carbon generally means more capacity, which is why a thin carbon-coated sheet does less than a proper carbon layer. For the full list of things filters cannot catch, see what air purifiers cannot remove.

Fix the Source First: Toilet, Kitchen, Bins and Damp

Most persistent smells at home have a physical source you can find and fix in an afternoon:

Smell	Usual source	Fix
Toilet or sewer smell	Dry floor trap or nahani trap in a little-used bathroom; loose WC seal	Pour water into floor traps weekly; get the seal or trap checked by a plumber
Urine smell	Around the WC base, grout, bathroom mats	Scrub grout and the WC base, wash or replace mats, keep the floor dry
Kitchen smell	Sink drain, greasy chimney filter, waste bin	Clear the drain, degrease the baffle filter, empty wet waste daily
Musty smell	Damp wall, leak, cupboards that never get air	Fix the leak, dry the wall, air cupboards on sunny days
Pet smell	Litter tray, bedding, carpets	Clean the litter tray daily, wash bedding weekly
Fridge or bin smell	Spoiled food, bin liners	Clear out, wash the bin, use lidded bins

Some sources have their own guides. For mould and monsoon damp, see musty damp smell and mould in the monsoon. For litter, bedding and fur, see pet smell and dander at home. For the sharp smell of fresh paint and new furniture, see new paint and furniture smell.

Rule of thumb: if a smell is strongest in one spot, the answer is in that spot. A purifier is for the smell that is left once the source is gone.

Air Purifier With Fragrance or Aroma Diffuser: Why It Masks

Search for an air purifier for smell and you will see models with a fragrance slot, an aroma diffuser or an “air freshener” mode. They make a room smell different, not cleaner, and they work against the purifier’s own job:

They mask, they do not remove. Fragrance covers the bad smell with a stronger one. The source molecules are still in the air.
They add VOCs. Fragrances, sprays and plug-in fresheners are themselves volatile organic compounds. You are adding gases to air you were trying to clean.
They load the carbon. A carbon layer cannot tell a fragrance molecule from an odour molecule, so it fills up with the scent you added.
They hide warnings. A sewer or burning smell is information. Covering it can delay a repair.

The same goes for agarbatti or dhoop lit to cover a smell: it adds smoke and fine particles on top. Our guide to agarbatti and dhoop smoke indoors explains what that smoke does indoors.

Exhaust Fans for Bathroom and Cooking Smell

For toilets and kitchens, an exhaust fan beats a purifier every time, because it pushes the smelly air out of the home instead of trying to clean it inside.

Bathrooms: run the exhaust during and for a while after use, and after every bath to clear moisture that feeds mould. Keep the bathroom door shut while it runs so it pulls air from the rest of the home through the bathroom, not the other way.
Kitchens: switch the chimney or exhaust on before you heat the oil, not when the smoke appears. Leave it running after you switch off the gas.
Clean the fan. A greasy, dusty exhaust moves far less air. Wipe the blades and grille every few months.
No exhaust? A window kept slightly open with the door shut is the next best thing.

Boon Airvana has an activated carbon stage for odours and a TVOC reading that shows when gases from cooking, sprays or paint are rising in the room.

See Boon Airvana →

Why the Smell Came Back

A common complaint: the purifier seemed to work for a few weeks, then the smell came back. There are four usual reasons:

The carbon is full. Saturated carbon stops adsorbing. A filter that has handled heavy smoke or cooking for months may need replacing even if it still looks fine.
The source never went away. The purifier was keeping pace with a dry drain trap or damp wall, and fell behind when the source got stronger, often in the monsoon.
Fabrics are releasing it. Curtains, sofas, mattresses and carpets soak up odour molecules and release them for days. Wash or air them.
The filter itself smells. A filter that got damp, or a pre-filter clogged with greasy dust, can start to smell. Wash the pre-filter if it is washable and check the main filter.

Smells That Mean Something: Gas, Sewer, Burning

Some smells are not an air-quality problem but a safety one. Do not try to purify these away:

Gas smell (LPG or piped gas): leave the room, turn off the regulator or supply valve if you can do it safely, open doors and windows, do not operate electrical switches, lighters or flames, and call your gas agency or emergency helpline from outside.
Persistent sewer smell: a broken trap, cracked pipe or blocked vent stack. Call a plumber or your society’s maintenance team.
Burning or hot plastic smell: switch off and unplug the appliance nearby, check sockets and wiring, and call an electrician if you cannot find the source. If the smell comes from a purifier itself, stop using it and contact the brand’s service team.
Smell with symptoms: if a smell comes with headache, dizziness, nausea or breathing trouble, get into fresh air and see a doctor.

Where Boon Airvana Fits

Boon Airvana is 1 air purifier, 2 H13 HEPA filters and 8 sensors. For smells, the useful parts are its activated carbon stage, which takes up odours and some gases, and its TVOC sensor, which shows when gases from cooking, cleaning sprays, fresheners or paint are rising. TVOC drives a cooking-fume alert, so you can see whether a smell is being cleared or the source is still going. Its H13 HEPA filters, which catch 99.95% of particles in a single pass, handle the particle side of smoke.

It shares the limits above: carbon saturates, it will not fix a drain trap or a damp wall, and it has no fragrance mode because adding scent is not cleaning. Filter changes come by reminder based on the air it has handled, and the pre-filter is washable. Airvana is ₹14,900 at the time of writing.

Frequently Asked Questions

Can an air purifier remove bad smells?

Partly. The HEPA filter in a purifier catches particles, not the gas molecules that make up most smells, so it helps only with the particle part of smoke. An activated carbon layer takes up some odour molecules until it saturates. For toilet, urine, kitchen or damp smells, fixing the source and running an exhaust fan matter more than any purifier.

Will an air purifier remove bathroom smell or toilet smell?

Not on its own. Bathroom and toilet smells usually come from a dry floor trap, a loose toilet seal, stained grout or damp mats. Pour water into floor traps weekly, scrub the base and grout, keep the floor dry and run the exhaust fan with the door shut. A purifier outside the bathroom cannot keep up with a live source.

Is an air purifier with fragrance a good idea?

Not if you want cleaner air. Fragrance and aroma diffuser features cover a bad smell with a stronger one rather than removing it, add volatile organic compounds to the room, and fill the carbon layer with the scent you added. They can also hide a smell that is warning you about a drain or electrical problem.

Can an air purifier remove smoke smell?

It helps more with smoke than with most other smells. HEPA filters catch the fine smoke particles, and activated carbon takes up some of the smelly gases. Smoke smell also clings to curtains, sofas and bedding, so wash or air them. Heavy daily smoke indoors will saturate the carbon faster.

Why does my room still smell after running an air purifier?

Usually the source is still there, the carbon layer is saturated, or fabrics are slowly releasing the smell. Find and fix the source, wash curtains and covers, clean the pre-filter and check whether the filter is due for replacement. A smelly filter that got damp or greasy also needs attention.

What should I do if I smell gas at home?

Leave the room, turn off the regulator or supply valve only if it is safe, open doors and windows, and do not operate electrical switches, lighters or any flame. Call your gas agency or emergency helpline from outside. A gas smell is a safety issue, never something to run an air purifier against.

Fix the source, run the exhaust, and let Boon Airvana’s activated carbon and TVOC reading handle what is left. ₹14,900 at the time of writing.

See Boon Airvana →

November 3, 2026

Air Purifier Sensors: Why They Matter and What Each One Measures

An air purifier with a sensor can see what it is cleaning. It measures particles, and on better units gases too, every few seconds, speeds up when the air gets worse and slows down once the room is clean. Without sensors, a purifier runs at whatever speed you set, so it either wastes power and filter life on clean air or under-cleans when cooking, incense or smog push pollution up.

Picture a purifier with no sensor on a November evening. You set it to speed 2 at 7 p.m. At 8 someone fries pakoras, at 9 smoke from a bonfire down the lane drifts in through a gap in the window, and by midnight the room is clean but the fan is still on speed 2. It has no idea any of this happened. A fixed-speed purifier forces you to guess, and the guess is usually wrong in one of three ways:

Over-cleaning: running on high when the air is already clean, which wastes electricity, adds noise and uses up filter life for nothing.
Under-cleaning: running on low when pollution spikes, so the room stays polluted long after the source has gone.
No feedback: you cannot tell whether the purifier is working, whether the room is too big for it, or whether a window left open is undoing its work.

A sensor fixes all three by closing the loop: measure, respond, measure again. It also tells you something about your own home: when the air gets bad and what usually causes it. For the wider list of features worth paying for, see the air purifier features that matter. This guide is only about the sensors.

Particle Sensors: Laser vs Infrared

Particle sensors do the heavy lifting, because fine particles, PM2.5 above all, are what drive the AQI in Indian cities for much of the year. There are two common designs, and they are not equal.

Laser particle sensors. A tiny fan pulls a thin stream of air through a chamber where a laser beam crosses it. Every particle that passes scatters a flash of light onto a detector, and the size of that flash relates to the size of the particle. The sensor can therefore count particles and sort them into size bands, reported as PM1.0, PM2.5 and PM10 in µg/m³. Because it actively draws air in, it responds within seconds.

Infrared dust sensors. Cheaper units often use an infrared LED and a light detector instead. Rather than counting particles one by one, they measure the overall light scattered by a cloud of them. That gives a rough dust level, often shown as a single number or a coloured ring, but it is weak on the smallest particles and cannot separate PM1.0 from PM10 with any confidence. Many have no fan of their own and depend on air drifting past, so they react slowly.

What the three sizes tell you:

PM10 includes coarse dust: road dust, construction dust, the cloud that rises when someone sweeps.
PM2.5 is fine particles from smoke, vehicle exhaust, cooking and winter smog. It is the number AQI reports usually lead with.
PM1.0 is the finest fraction, dominated by burning: agarbatti, tadka smoke, a mosquito coil, a candle. When PM1.0 jumps while PM10 barely moves, something is burning.

One quirk worth knowing: in very humid air, such as a monsoon morning, particles take up water and swell, so laser sensors can read a little high. That is physics, not a fault. The difference between the particle sizes is covered in PM2.5 vs PM10.

TVOC, eCO₂ and NO₂: The Gas Readings

Particles are only part of the picture. Gas sensors pick up what a HEPA filter cannot catch at all.

TVOC (total volatile organic compounds). A combined reading of the many carbon-based gases released by hot cooking oil, gas burners, cleaning sprays, room fresheners, fresh paint, new furniture, perfume and incense. A TVOC sensor does not tell you which compound is present, only that the total has gone up. A spike while you cook is normal. A high reading that stays up for days in a freshly painted room is a reason to ventilate more.

eCO₂ (estimated carbon dioxide). This reading is often misunderstood. A true CO₂ measurement needs an NDIR sensor, which measures how much infrared light CO₂ molecules absorb. An eCO₂ value is inferred instead, from other sensor readings that tend to rise as people fill a closed room. It is useful as a stuffiness indicator and it moves in the right direction, but treat the number as an estimate, not a meter reading. For reference, outdoor air is roughly 420 ppm, and around 1,000 ppm indoors is a widely used rule of thumb that a room needs more fresh air.

NO₂ (nitrogen dioxide). NO₂ forms when fuel burns at high temperature, so its main sources are vehicle exhaust outdoors and gas burners indoors. A rising NO₂ reading with the windows open usually points to traffic outside; a rise while the stove is on points to the kitchen.

Temperature and Humidity

Temperature and humidity do not feed into the AQI, but they explain a lot about a room. Persistently damp air encourages mould and dust mites and leaves cupboards smelling musty; very dry winter air can leave throats and skin feeling dry. Temperature tells you how a closed room behaves through the day and how hard the AC is working. A purifier does not change either value. For damp, a dehumidifier or an AC on dry mode does that job.

Sensor by Sensor: What to Do With Each Reading

Sensor	What it reads	What it tells you to do
PM1.0 (laser)	Finest particles, mostly from burning	Find the source: incense, tadka, coil, candle. Close the room and let the purifier run.
PM2.5 (laser)	Fine particles: smoke, exhaust, smog	Keep windows shut on bad-air days, run on Auto, check outdoor AQI before airing.
PM10 (laser)	Coarse dust	Mop and wipe, close road-facing windows, clean the pre-filter more often.
TVOC	Combined gases from cooking, sprays, paint, perfume	Run the chimney or exhaust, ventilate, cut back on sprays and fresheners.
eCO₂ (estimated)	Stuffiness, inferred from occupancy	Open a window or door for fresh air. A purifier cannot lower CO₂.
NO₂	Combustion gas from traffic and gas burners	Close road-facing windows at rush hour; use the kitchen exhaust while cooking.
Temperature	How warm the room is	Context for AC, fan and window decisions.
Humidity	Moisture in the air	Dry out damp rooms; ventilate after bathing and cooking.

Boon Airvana reads PM1.0, PM2.5, PM10, TVOC, eCO₂, NO₂, temperature and humidity every second, and turns them into alerts you can act on.

See Boon Airvana →

How Auto Mode Uses the Readings

In Auto mode, the purifier turns its particle readings into an AQI value and sets the fan to match: faster when the number climbs, slower when it settles. A well-tuned Auto mode reacts within seconds of a spike, steps down once the room is clean, and does not hunt up and down every few seconds. In daily use, that pays off in three ways:

Electricity and filters. The fan spends long stretches on low instead of high, so less power is used and the filter fills more slowly.
Noise. On clean evenings it stays quiet without you touching it.
Speed when it counts. When you light a diya or start frying, it reacts before you would have noticed the smell.

Auto can only respond to what it measures. If the room is open to a smoggy street, it will run high all evening, and the display will show you why. That is useful information too: close the window. Sensor data can also feed an app so you see trends over days and weeks; app features, schedules and voice assistants are covered in our guide to smart purifier apps, Alexa and Google Home.

In one line: sensors turn a purifier from a fan you set and forget into a system that reacts to your home, and tells you what it is reacting to.

What Sensors Cannot Do

They measure size, not identity. A particle sensor cannot tell pollen from road dust, or smoke from mould spores. A rising PM2.5 reading means “more fine particles”, not “what kind”.
They do not measure carbon monoxide. CO from a generator, a gas geyser, an angeethi or a faulty heater does not show up on a particle, TVOC or eCO₂ reading. If you burn fuel indoors, a dedicated CO alarm is the device that matters.
They are not lab instruments. Home sensors are built for trends and comparison, not certified measurement. Two different devices in the same room may disagree; watch how the number moves rather than its last digit.
They drift and need checking. Sensors age, and dust can build up in a particle chamber. A good purifier runs self-diagnostics and flags a fault instead of quietly reporting wrong numbers.
Placement changes what they see. A sensor beside the stove or under an AC vent reads different air from the middle of the room.

To cross-check a purifier’s numbers, or to measure your air without one, see how to check air quality at home.

How Boon Airvana Uses Its 8 Sensors

Boon Airvana is 1 air purifier, 2 H13 HEPA filters and 8 sensors. Its AtmoScan sensing, developed by Boon Labs over two years, reads eight parameters every second: PM1.0, PM2.5 and PM10 by laser-based particle sensing, plus TVOC, eCO₂, NO₂, temperature and humidity. The eCO₂ value is estimated, inferred rather than measured directly by an NDIR CO₂ sensor, and we would rather you knew that.

The readings drive Auto mode and a set of smart alerts:

Fresh air: eCO₂ is rising and the room needs outdoor air.
Cooking fume: TVOC has jumped, usually from the kitchen.
Traffic pollution: NO₂ is rising, often from the road outside.
Allergy: PM2.5 and PM10 are rising together.
Clean pre-filter and change filter: reminders based on the air the purifier has actually handled, not a fixed calendar.

Continuous self-diagnostics watch the sensors, filters and motor, and the Boon app shows a diagnostics report alongside charts, trends and insight cards. The full-colour display can show full metrics, AQI only or an AQI graph. Coverage is up to about 484 sq ft, and the price is ₹14,900 at the time of writing. It shares every limit above: it cannot tell you what a particle is made of, and it does not measure carbon monoxide.

Frequently Asked Questions

Is an air purifier with a sensor worth it?

For most Indian homes, yes. Pollution changes through the day with cooking, incense, traffic and smog, and a sensor lets the purifier speed up during spikes and slow down when the air is clean. That saves electricity and filter life, keeps it quieter, and shows you whether the room is actually getting cleaner. A fixed-speed purifier leaves all of that to guesswork.

What is the difference between a laser and an infrared dust sensor?

A laser sensor draws air through a chamber with a small fan and counts individual particles by the light each one scatters, so it can report PM1.0, PM2.5 and PM10 separately and respond within seconds. An infrared sensor measures overall scattered light from a cloud of particles, gives a rougher single dust level, struggles with the finest particles and usually reacts more slowly.

Is eCO₂ on an air purifier the same as CO₂?

No. eCO₂ means estimated CO₂. It is inferred from other sensor readings that rise as people occupy a closed room, rather than measured directly with an NDIR CO₂ sensor. It is a useful stuffiness indicator and moves in the right direction, but treat the number as an estimate. As a ventilation rule of thumb, around 1,000 ppm indoors suggests the room needs fresh air.

Can an air purifier sensor detect carbon monoxide?

No. Particle, TVOC and eCO₂ sensors do not detect carbon monoxide, and an air purifier does not remove it. CO comes from burning fuel, such as generators, gas geysers, angeethis and faulty heaters. If you use any of these indoors, fit a dedicated CO alarm, keep the space ventilated and have the appliance checked.

Why does my purifier’s PM2.5 reading differ from the AQI app?

Most AQI apps show outdoor readings from monitoring stations, often some distance away, while your purifier reads the air in your room. Indoor and outdoor levels can be very different, especially with windows shut. Apps also often show an AQI index rather than PM2.5 in µg/m³. Home sensors are best used for trends rather than exact figures.

What does TVOC mean on an air purifier?

TVOC stands for total volatile organic compounds. It is a combined reading of carbon-based gases from sources such as hot cooking oil, gas burners, cleaning sprays, room fresheners, paint, new furniture and perfume. It does not name the gas. A short spike while cooking is normal; a reading that stays high for days is a sign to ventilate more.

See how Boon Airvana’s AtmoScan reads eight parameters every second and tells you what to do about them. ₹14,900 at the time of writing.

See Boon Airvana →

November 2, 2026

Living Near a Busy Road? How Traffic Pollution Gets Indoors

If your flat faces a main road or a flyover, traffic pollution reaches you as three things: fine exhaust particles, nitrogen dioxide gas, and coarse road dust. They come in through open windows, sliding-window gaps and every unsealed hole in the road-facing wall. You can cut a lot of it by timing when you ventilate, sealing the road side and running a HEPA purifier, but be clear about the limits: a purifier handles particles well, gases only partly, and carbon monoxide not at all.

What Traffic Brings Into Your Flat

A busy road produces a mix of pollutants, and they behave differently once they reach your home.

Pollutant	Where it comes from	How it behaves indoors
Fine particles (PM2.5, PM1.0)	Vehicle exhaust, especially diesel; burning fuel	Stays airborne for a long time, slips through small gaps, has no smell
NO₂ (nitrogen dioxide)	Fuel burning at high temperature in engines	A gas, so HEPA cannot catch it; drifts in with outdoor air
Road dust (PM10)	Dust kicked up by tyres, brake and tyre wear, construction nearby	Heavier, settles on sills, floors and furniture, then gets stirred up again
Carbon monoxide	Incomplete burning of fuel	A gas no home purifier removes; dilutes with ventilation

The grey film on your window sill is mostly the coarse fraction, PM10. The fine fraction is invisible, and that is the part that drives the AQI. Our guide on PM2.5 vs PM10 explains why the two sizes matter differently.

How It Gets Indoors

Closing the windows helps, but most flats are far from airtight. Traffic pollution finds its way in through:

Sliding windows. The overlap between panes and the tracks at the bottom leave gaps even when the window is latched shut.
Window frames. Old or poorly finished frames often have cracks between the frame and the wall.
AC pipe holes and ventilators. The hole drilled for a split AC’s pipes is frequently left half-open, and ventilator grilles are open by design.
Balcony doors. Gaps at the bottom and sides of a balcony door facing the road.
Exhaust fans. When a kitchen or bathroom exhaust runs, it pulls replacement air in through every gap, including the ones on the road side.

You can find most leaks yourself. On a windy day, run the back of your hand along a closed window frame and feel for a draught, and look for thin lines of dark dust on the sill or frame, which mark where outside air has been getting through.

Which Rooms and Floors Get More

Without measuring your own home, you can still predict the pattern from basic physics:

Road-facing rooms get more than rooms at the back of the flat, because they are closest to the source and take the most direct infiltration.
Lower floors get more road dust, because heavier PM10 settles out before it rises far. Fine particles and gases mix more evenly, so higher floors are not immune to those.
Flyovers change the picture. A flyover puts traffic at the height of the first few floors, so flats level with the deck can sit right beside the exhaust.
Traffic signals and junctions are worse than open stretches, because vehicles idle, stop and accelerate there.
Balconies act as dust traps. Dust that lands there is carried in on feet and stirred up whenever the balcony door opens.

If you have a choice, make the room at the back of the flat the main bedroom, and keep the road-facing room for daytime use.

Rush Hour and When to Open Windows

Traffic pollution follows the traffic. In most Indian cities, the morning and evening rush hours are the worst times to have road-facing windows open. In winter, still, cold air in the late evening and early morning holds exhaust close to the ground, so pollution can stay high well after the roads have cleared.

Keep road-facing windows shut at rush hour, morning and evening.
Ventilate from the quiet side. Open windows that face away from the road, or a courtyard or inner shaft, for fresh air.
Pick the lull. Late morning to mid-afternoon, when traffic eases and, in winter, the air mixes better, is usually a gentler window.
Check the number. Look up your city on AQI by city; for example, the Delhi AQI page shows the current reading before you open up.
Air briefly, then close. A few minutes of cross-ventilation is enough to freshen a room; then shut up and let the purifier catch up.

Do not seal yourself in permanently. A closed room still needs fresh air from time to time, or carbon dioxide and stale air build up.

Sealing Road-Facing Windows

Sealing gaps on the road side does more than any appliance to stop pollution reaching you in the first place. Most of it is a weekend job, and the road-facing bedroom is the place to start, since that is where you spend the longest stretch with the windows shut:

Weatherstrip the frames. Self-adhesive foam or rubber strips along the frame where the window closes against it.
Fit brush seals on sliding windows. Pile or brush strips along the overlap and the bottom track close the gaps that sliders always leave.
Seal frame-to-wall cracks with silicone or a suitable sealant.
Close the AC pipe hole properly around the pipes, with sealant or a fitted cover.
Add a door sweep to the bottom of a road-facing balcony door.
Clean sills wet, not dry. A damp cloth picks road dust up; a dry duster sends it back into the air.

Heavy curtains reduce noise and some dust, but they are not a seal. Keep at least one window on the quiet side easy to open, so you can still ventilate.

Boon Airvana’s traffic-pollution alert reads NO₂, so you know when the road is getting into your room and when to close the windows.

See Boon Airvana →

What a Purifier Removes, and What It Does Not

A HEPA purifier in a closed room is good at the particle part of traffic pollution. It catches fine exhaust particles and road dust as the same air passes through it again and again. The gas part is harder:

Particles: HEPA traps PM2.5, PM1.0 and PM10 well, and a washable pre-filter takes the coarse dust before it reaches the HEPA layer. In a dusty, road-facing flat, expect to clean the pre-filter more often.
NO₂ and other gases: activated carbon can take up some gases, but its capacity is limited and it saturates. It is not a dependable fix for NO₂. Keeping the gas out by timing ventilation and sealing gaps matters more.
Carbon monoxide: a purifier does not remove it. Ventilation dilutes it; nothing in a purifier captures it.

The honest version: seal the road side, time your windows, and let HEPA handle the particles. Do not expect any purifier to scrub the gases out of traffic air.

Our guide on what air purifiers cannot remove goes through each of these limits. If anyone at home has asthma, a persistent cough or breathing difficulty that seems worse in the road-facing rooms, see a doctor; a purifier lowers particle exposure, it does not treat a condition.

Where Boon Airvana Fits

Boon Airvana is 1 air purifier, 2 H13 HEPA filters and 8 sensors. Its AtmoScan sensing, developed by Boon Labs over two years, reads eight parameters every second, and three of them map straight onto traffic pollution:

NO₂ drives a traffic-pollution alert, so you know when the road is reaching your room and it is time to shut the road-facing windows.
PM2.5 and PM10 drive an allergy alert when both rise together, the pattern of dust plus exhaust.
A clean pre-filter reminder tells you when the washable mesh needs attention, which comes around sooner in a dusty flat.

Dual suction draws air from both sides through the two H13 HEPA filters, with activated carbon for odours and some gases. Auto mode follows the real-time AQI, so the fan picks up at rush hour and settles when traffic eases. Coverage is up to about 484 sq ft. It will not remove NO₂ in any dependable way and does not touch carbon monoxide, but it will tell you when the gas is rising so you can act. Airvana is ₹14,900 at the time of writing.

Frequently Asked Questions

Is it bad to live near a main road in an Indian city?

Flats near main roads and flyovers usually get more fine exhaust particles, nitrogen dioxide and road dust than flats set back from traffic. You can reduce how much gets in by keeping road-facing windows shut at rush hour, ventilating from the quiet side, sealing gaps and running a HEPA purifier. See a doctor if anyone has persistent breathing symptoms.

How does traffic pollution get into a closed flat?

Most flats are not airtight. Pollution comes in through sliding-window gaps and tracks, cracks around window frames, half-open AC pipe holes, ventilators and gaps under balcony doors. Kitchen and bathroom exhausts also pull outdoor air in through every gap when they run. Weatherstrips, brush seals and sealant on the road side make a real difference.

Which floor is better for traffic pollution?

Higher floors usually get less coarse road dust, because heavier PM10 settles before rising far. Fine particles and gases mix more evenly, so upper floors still get some. Flats level with a flyover deck can be close to the exhaust. Road-facing rooms get more than rooms at the back, whatever the floor.

When should I open windows if I live near a busy road?

Avoid opening road-facing windows during morning and evening rush hours, and in winter during the late evening and early morning when still air holds exhaust near the ground. Ventilate from the side away from the road, ideally in the late-morning to afternoon lull, and check your city’s AQI first. Air briefly, then close up.

Can an air purifier remove NO₂ from traffic?

Not dependably. HEPA filters catch particles, not gases. Activated carbon can take up some gases, but its capacity is limited and it saturates, so it is not a reliable fix for nitrogen dioxide. Sealing the road side and timing ventilation keep more of it out. A purifier does not remove carbon monoxide at all.

Why is there so much black dust on my window sill?

On a road-facing sill, it is mostly road dust and exhaust soot: coarse PM10 from tyres, brakes and nearby construction, plus finer particles from vehicle exhaust. Seal the window gaps, keep the window shut at rush hour and wipe the sill with a damp cloth rather than dusting it dry, which sends the dust back into the air.

Boon Airvana’s NO₂ traffic-pollution alert tells you when to shut the road-facing windows, and its H13 HEPA filters handle the dust. ₹14,900 at the time of writing.

See Boon Airvana →

November 2, 2026

Why Does My Room Feel Stuffy? Indoor CO₂ in Indian Homes

A room feels stuffy mainly because the people in it have been breathing out carbon dioxide, moisture and body odours into air that is not being replaced. Close the door and windows, add two or three people and a few hours, and CO₂ builds up. The fix is fresh outdoor air, timed for when the outdoor air is at its cleanest; no air purifier removes CO₂.

Why Closed Rooms Get Stuffy

Every breath you take in is roughly outdoor air. Every breath you let out carries far more CO₂, plus water vapour and the faint odours that bodies give off. In a room with steady fresh air, that is diluted and carried away. In a sealed room, it accumulates. The more people, the smaller the room and the longer the door stays shut, the faster it builds.

Indian homes hit this in a few familiar situations:

Winter smog season. From late October, many families in Delhi NCR and across North India keep every window shut for weeks to keep PM2.5 out. That works for particles and traps everything else.
AC bedrooms. A split AC cools and recirculates the air already in the room. It does not bring in fresh outdoor air, so a closed AC room behaves like a sealed box.
Small bedrooms with two or three sleepers. A couple with a child in a 10 × 12 ft room, door shut for seven or eight hours, is a classic recipe for a heavy morning.
Newer, well-sealed flats. Tighter windows and fewer ventilators keep out dust and noise, and also keep out fresh air.
Home offices and study rooms. One or two people working for hours with the door closed to shut out household noise.

Signs Your Room Needs Fresh Air

You rarely notice stuffiness from inside, because your nose gets used to it. The signs show up in other ways:

Waking with a heavy head or feeling groggy even after a full night’s sleep.
Drowsiness or difficulty focusing in a closed room by mid-afternoon.
A stale, close smell that you notice only when you walk back in from outside.
Condensation on the inside of windows on cool mornings, a sign of moisture from breath building up too.
The feeling eases quickly when you step onto the balcony or open a window.

These are common and usually harmless signs of a room that needs airing. If they come with other symptoms, or do not ease with fresh air, read the last section of this guide.

CO₂ Numbers: 420 and 1,000 ppm

CO₂ is measured in parts per million (ppm). Two numbers are enough for home use:

Reading	What it means
About 420 ppm	Typical outdoor air. A well-aired room sits not far above this.
Around 1,000 ppm	A widely used rule of thumb that the room needs more fresh air.
Well above 1,000 ppm	The room has gone a long while without air exchange. Air it.

Treat 1,000 ppm as a ventilation signal, not a health limit. It tells you that the air in the room is not being replaced fast enough, and CO₂ stands in for everything else that builds up alongside it, such as humidity, odours and gases from cooking and cleaning. Many home devices show an estimated value, labelled eCO₂, which is inferred from other readings rather than measured directly. It trends the right way and is useful for deciding when to air the room; just do not read the last digit as exact.

The Smog-Season Dilemma: Window Open or Shut?

This is the real problem in an Indian winter. On a day when the outdoor AQI is Very Poor or Severe, opening a window lets PM2.5 pour in. Keeping it shut lets CO₂ and stale air pile up. Neither extreme is right.

Windows open all day: fresh air, but the room fills with outdoor particles, and a purifier cannot keep up with an open window.
Windows sealed for days: particles stay low, but the room grows stuffy, damp and smelly, and you lose the benefit of a clean but airless room.

The workable answer sits in between: short, deliberate bursts of fresh air at the right moments, and a purifier to clear the particles that come in with it. Our guide on how to protect your home from winter smog covers the particle side of winter in more detail.

How to Air a Room Without Letting the Smog Win

Check the outdoor air first. Look up your city on AQI by city. In winter, outdoor pollution is often worse late at night and early in the morning, when cold, still air holds smoke and exhaust close to the ground. Late morning to afternoon, once the air mixes, is usually the gentler window.
Air in short, timed bursts. Open up for a few minutes rather than leaving a window ajar all day. A short burst swaps out stale air quickly while letting in less pollution overall.
Cross-ventilate. Open two openings on opposite sides of the flat, or a window and the room door, so air flows through rather than sitting still.
Use your exhaust fans. Kitchen and bathroom exhausts push air out, and fresh air is drawn in through gaps elsewhere. Running them for a while helps the whole flat.
Leave the bedroom door ajar at night where privacy and noise allow, so the bedroom shares air with the rest of the home instead of sealing in two or three sleepers.
Spread people out. If a small room regularly sleeps three, it will get stuffy faster than a larger one sleeping two.
Close up and let the purifier work. Once the room has been aired, shut the windows and let the purifier bring the particles back down.

For more on how bedroom air affects how you feel in the morning, see bedroom air quality and sleep.

Boon Airvana does not remove CO₂. Its fresh-air alert tells you when estimated CO₂ is rising, so you know when to open the window, and Auto mode clears the particles afterwards.

See Boon Airvana →

What an Air Purifier Can and Cannot Do Here

Plainly: no air purifier removes CO₂, and none adds oxygen. HEPA filters catch particles, and CO₂ is a gas made of molecules far smaller than any particle. Activated carbon holds some odour and gas molecules, but it is not a CO₂ remover. Any product that claims to “refresh” a stuffy room without bringing in outdoor air is overselling. For the full list of things a purifier will not fix, see what air purifiers cannot remove.

What a purifier does do in this situation is make ventilation less costly. When you air the room on a smoggy day, some PM2.5 comes in. A purifier in a closed room brings it back down afterwards, so you can afford to ventilate more often.

The honest split: fresh air fixes CO₂; a purifier fixes particles. You need both habits in smog season, and neither does the other’s job.

This is where Boon Airvana’s sensors earn their place. Among its eight readings is eCO₂, an estimated CO₂ value inferred rather than measured directly. When it rises, Airvana raises a fresh-air alert: the room needs outdoor air. You open the window; Airvana cannot do that part for you. Once you close up again, its Auto mode follows the real-time AQI and clears the particles that came in, and its PM2.5 reading shows you how quickly the room recovers. Airvana is ₹14,900 at the time of writing.

When It Is Not Just Stuffiness

Ordinary stuffiness clears within minutes of fresh air. See a doctor if you have headaches that keep coming back, breathlessness, chest discomfort, or dizziness that does not ease once the room is aired, or if anyone at home has asthma or another lung condition that seems worse indoors.

Be especially alert if several people, or pets, feel unwell in the same room at the same time, or if symptoms such as headache, nausea or dizziness appear when a gas geyser, heater, generator, angeethi or sigri is running. That can point to carbon monoxide, which has no smell. Get everyone into fresh air, switch the appliance off, and have it checked before using it again. A purifier will not help with carbon monoxide, and neither will an eCO₂ reading. Never run fuel-burning heaters or angeethis in a closed room, and fit a CO alarm if you use them at all.

Frequently Asked Questions

Why does my bedroom feel stuffy in the morning?

Overnight, everyone in a closed bedroom breathes out carbon dioxide, moisture and body odours into air that is not being replaced. With the door and windows shut, or a split AC recirculating the same air, it builds up for seven or eight hours. Airing the room in the morning, leaving the door ajar and spreading sleepers across rooms all help.

What is a normal CO₂ level in a room?

Outdoor air is roughly 420 ppm, and a well-ventilated room sits not far above that. Around 1,000 ppm indoors is a widely used rule of thumb that a room needs more fresh air. Treat it as a ventilation signal rather than a health limit. Many home devices show an estimated value, eCO₂, which is useful for trends but not exact.

Does an air purifier remove CO₂?

No. No air purifier removes carbon dioxide or adds oxygen. HEPA filters catch particles, and activated carbon holds some odours and gases, but neither removes CO₂. The only fix for a stuffy room is fresh outdoor air. A purifier with an eCO₂ reading can tell you when to ventilate, and can clear the particles that come in when you do.

Should I open windows when the AQI is high?

Not for long. On Very Poor or Severe days, keep windows shut most of the time, but air the room in short, timed bursts when the outdoor reading is lowest, often late morning to afternoon in winter. Cross-ventilate for a few minutes, then close up and let an air purifier bring the particles back down.

Do indoor plants reduce CO₂ in a bedroom?

Not in any way you would notice. Plants take up carbon dioxide in daylight, but far too slowly to offset what people breathe out in a closed room, and at night they do not take it up at all. A few plants are pleasant to have, but opening a window or door is what actually brings CO₂ down.

Can a stuffy room cause headaches?

Many people feel heavy-headed or groggy in a stuffy room, and it usually eases quickly with fresh air. See a doctor if headaches keep coming back or come with breathlessness or dizziness. If several people feel unwell together, especially near a gas geyser, heater or generator, suspect carbon monoxide: get to fresh air and have the appliance checked.

Let Boon Airvana’s fresh-air alert tell you when to open the window, then let Auto mode clear the smog that comes in. ₹14,900 at the time of writing.

See Boon Airvana →

November 2, 2026

Kitchen Fumes: How Cooking Smoke Spreads Through Your Home and What Clears It
In This Guide

Where Fumes Go After the Tadka

How Long Smells and Fine Particles Linger

TVOC in Plain Words

Why a Fading Smell Does Not Mean Clean Air

A Sequence That Works

What Activated Carbon Does, and Where It Stops

Where Boon Airvana Fits

Frequently Asked Questions
Kitchen fumes do not stay in the kitchen. Hot air from the stove rises, rolls along the ceiling and slips through every open doorway, so smoke, fine particles and gases from a tadka reach the living room and bedrooms within minutes, especially in open-plan and compact 2BHK flats. What clears them is a sequence: extract at the source while you cook, contain the kitchen, ventilate, then let a purifier in the next room finish the job.

This guide picks up where two others leave off. For what Indian cooking puts into the air in the first place, see Indian cooking and indoor air pollution. For choosing between a chimney and a purifier, see chimney vs air purifier for the kitchen. Here the question is what happens after the oil hits the pan.

Where Fumes Go After the Tadka

When you heat oil and drop in mustard seeds, jeera or chillies, you create a hot plume of smoke, oil droplets, fine particles, water vapour and gases. Because it is hot, it rises fast. If a chimney or exhaust is not capturing it right above the pan, the plume hits the ceiling, spreads sideways and starts moving through the home.
- Open-plan kitchens. Where the kitchen opens straight onto the dining and living area, there is nothing to stop the plume. The whole common space shares the kitchen’s air.
- Compact 2BHK flats. Even with a kitchen door, it is often left open for light and air. A short corridor carries fumes to bedrooms a few steps away.
- Ceiling fans and ACs. A running ceiling fan mixes fumes into every corner of the room. A split AC recirculates whatever has drifted in, rather than removing it.
- Soft furnishings. Curtains, sofas, cushions and bedding take up odour molecules and release them slowly for hours, which is why a room can smell of last night’s dinner the next morning.
Gas burners add to this even when nothing is frying, because burning gas releases combustion products, including NO₂, into the kitchen air.

How Long Smells and Fine Particles Linger

There is no single answer, because it depends on how much was cooked, how it was cooked and how well the home is ventilated. The pattern, though, is consistent. Fine particles from frying and tempering spike sharply during cooking and then fall back gradually. In a well-ventilated home, that takes a fraction of the time it takes in a closed flat during smog season, when windows stay shut and the particles have nowhere to go.

The very finest particles, the PM1.0 fraction that burning produces, stay airborne longest because they are too light to settle. Larger oil droplets settle faster, which is why kitchen cabinets, walls and fan blades turn sticky over time. Smells follow a slower curve again, because they come back off fabrics and surfaces long after the air itself has cleared.

TVOC in Plain Words

TVOC stands for total volatile organic compounds. In plain words: a combined measure of the many carbon-based gases that float off hot, cooking and cleaning things. In a kitchen they come from:
- Hot oil and ghee, especially when heated to smoking point or reused.
- Gas burners, as part of the combustion products.
- Cleaning sprays and floor cleaners used to wipe down after cooking.
- Room fresheners and incense lit to cover the cooking smell, which add their own VOCs on top.
A TVOC reading does not tell you which gas is present, only that the total has risen. A spike while cooking is normal and expected. What matters is how quickly it comes back down, and that depends on what you do next.

Why a Fading Smell Does Not Mean Clean Air

The nose is a poor air-quality meter, for two reasons. First, it gets used to a smell within minutes, so the people who stayed home stop noticing it long before it has gone; a visitor walking in notices straight away. Second, many fine particles have no smell at all. A room can smell clean while PM2.5 and PM1.0 are still well above where they started.

Rule of thumb: if your nose has stopped noticing the tadka, assume the air has not caught up yet. A particle reading tells you when it actually has.

This is also why covering the smell with a spray or agarbatti backfires. It swaps one smell for another and adds more particles and VOCs to air that is already loaded.

A Sequence That Works

No single device clears kitchen fumes on its own. The order of steps is what makes the difference:
1. Switch on the chimney or exhaust before you heat the oil, not when the smoke appears. Capture at the source is far more effective than chasing fumes around the flat later.
2. Cook on the burners under the hood and use lids where the recipe allows.
3. Keep the kitchen door shut while cooking, if you have one, so the exhaust pulls replacement air in through the kitchen rather than the plume escaping outwards.
4. Leave the exhaust running for a while after you switch off the gas. The plume does not stop the moment the flame does.
5. Ventilate if the outdoor air allows. Open the kitchen window and one on the far side of the flat for a few minutes. On smoggy days, keep it brief.
6. Run a purifier in the adjacent room on Auto, such as the dining or living area, with bedroom doors closed. It catches what escaped the kitchen.
7. Skip the freshener spray. Let extraction, airing and filtration do the work.
8. Keep the chimney clean. Greasy baffle filters capture far less.
One thing not to do: do not put an air purifier next to the stove. Grease and steam coat its filters and sensors, heat is hard on any appliance, and it cannot compete with a fresh plume at close range; that is the chimney’s job. Place it in the room the fumes spread into. Our guide on where to place an air purifier in an Indian home covers spacing and placement around fans and ACs.

Boon Airvana’s cooking-fume alert reads TVOC, and its PM1.0 tracking shows when the tadka smoke has actually cleared from the next room.
See Boon Airvana →

What Activated Carbon Does, and Where It Stops

HEPA filters catch particles, including fine smoke, but cooking smells are mostly gas molecules, too small for HEPA to hold. Activated carbon handles that part. It is charcoal treated to be full of microscopic pores, and odour molecules stick to its large internal surface. A purifier with a carbon layer can noticeably reduce cooking smells in a room.

It has limits:
- It saturates. Carbon has a finite amount of surface. Once it is full, it stops taking up odours. Heavy daily frying fills it sooner than light cooking.
- It is not a fix for every gas. It helps with odours and some gases, not all of them.
- It does not deal with carbon monoxide. No purifier does. Burners and appliances need proper ventilation and servicing.
- It cannot replace extraction. A small carbon layer in a room cannot match a chimney removing fumes at the stove.
If the smell of gas itself, rather than food, is ever noticeable, treat it as a possible leak: turn off the regulator, open windows, do not operate switches or lighters, and call your gas distributor. That is a safety issue, not an air-quality one.

Where Boon Airvana Fits

Boon Airvana belongs in step six of the sequence: the room next to the kitchen. Its AtmoScan sensing reads eight parameters every second, and two of them do the work after cooking. TVOC drives a cooking-fume alert, so you know when the kitchen’s gases have reached the room. PM1.0, read by laser alongside PM2.5 and PM10, shows the fine smoke rising and then falling, so you can see when the air has genuinely recovered rather than trusting your nose.

In Auto mode, the fan follows the real-time AQI, so it speeds up as fumes arrive and slows down once they clear. Air is drawn in from both sides through two H13 HEPA filters, with activated carbon for odours and a washable pre-filter. Filter changes come by reminder based on the air it has handled. It covers up to about 484 sq ft, and costs ₹14,900 at the time of writing. It is not a chimney replacement, and it should not sit by the stove.

Frequently Asked Questions

How do I stop kitchen smell spreading to bedrooms?

Turn on the chimney or exhaust before you heat the oil, keep the kitchen door shut while cooking if you have one, and leave the exhaust running for a while afterwards. Keep bedroom doors closed during cooking, ventilate briefly if the outdoor air allows, and run an air purifier on Auto in the room next to the kitchen.

How long do cooking fumes stay in the house?

It depends on how much was cooked and how well the home is ventilated. Fine particles spike during cooking and fall gradually, much more slowly in a closed flat during smog season. Smells last longer because curtains, sofas and bedding release them for hours. A particle reading shows when the air has actually recovered.

Can an air purifier remove cooking smell?

Partly. HEPA filters catch the fine smoke particles, and an activated carbon layer takes up some odour molecules, so a purifier can noticeably reduce cooking smell in a room. Carbon saturates over time, especially with heavy daily frying, and a purifier cannot replace a chimney or exhaust capturing fumes at the stove.

Should I keep an air purifier in the kitchen?

Not next to the stove. Grease and steam coat the filters and sensors, heat is hard on the unit, and it cannot compete with a fresh plume at close range. Use a chimney or exhaust in the kitchen and place the purifier in the adjacent dining or living area, where the fumes spread to.

Is gas stove smoke harmful indoors?

Burning gas releases combustion products, including nitrogen dioxide, and frying adds fine particles and gases. Run the chimney or exhaust whenever the burners are on and ventilate when you can. If you smell gas itself, turn off the regulator, open windows, avoid switches and flames, and call your gas distributor. See a doctor for persistent breathing symptoms.

Do room fresheners remove cooking smell?

No. Room fresheners and incense cover one smell with another, and they add their own particles and volatile organic compounds to air that is already loaded from cooking. Extraction while cooking, a few minutes of ventilation and an air purifier with activated carbon in the next room clear the air instead of masking it.

Put Boon Airvana in the room next to your kitchen: a TVOC cooking-fume alert, PM1.0 tracking and Auto mode. ₹14,900 at the time of writing.
See Boon Airvana →
November 2, 2026