A safe indoor AQI is 50 or below, the CPCB “Good” band. Anything up to 100 (“Satisfactory”) is acceptable for most healthy people, but children, older family members and anyone with asthma or heart disease do better when the room stays under 50. Above 100 indoors, it is time to close up, filter the air and cut indoor sources of smoke.
If you have searched “AQI kitna hona chahiye”, that is the answer in one line: aim for under 50 inside your home, treat 51 to 100 as fine for a short while, and act once it crosses 100.
The Short Answer
The AQI (Air Quality Index) turns several pollutants into one number on a 0 to 500 scale. Lower is better. In Indian cities during October and November, the number that drives the AQI is almost always fine particulate matter (PM2.5), so in practice “a safe AQI” means “a low level of fine particles”.
India’s AQI and its air-quality standards are written for outdoor air. There is no separate household number that you are required to meet, so the sensible approach is to borrow the outdoor bands and the health-based limits, and hold the air in the rooms where you spend most time, especially the bedroom, to the stricter end of them.
Rule of thumb: under 50 is the goal, under 100 is acceptable, over 100 indoors means you need to act, and over 200 indoors means the room is not protecting you at all.
The CPCB Bands and What to Do Indoors
These are the Central Pollution Control Board’s National AQI bands. The right-hand column is practical guidance for the inside of a home, not an official instruction.
| AQI | Band | What to do indoors |
|---|---|---|
| 0-50 | Good | Ventilate freely. Open windows for fresh air, especially after cooking. |
| 51-100 | Satisfactory | Fine for most people. Sensitive family members may notice symptoms; a purifier on low or Auto keeps the bedroom in the Good band. |
| 101-200 | Moderate | Keep windows mostly closed during the worst hours, ventilate briefly when outdoor air is cleaner, run a purifier in occupied rooms. |
| 201-300 | Poor | Windows closed, purifier running continuously in the bedroom and living room, avoid incense and frying without the chimney or exhaust on. |
| 301-400 | Very Poor | Treat the bedroom as a clean room: door shut, purifier sized for the room, gaps under doors reduced. Limit outdoor exercise. |
| 401-500 | Severe | Same as above, with everyone who is vulnerable kept in the cleanest room. If anyone has breathing difficulty, contact a doctor. |
When outdoor AQI goes past 400 or “500+”, the useful question is no longer what the city reads but what your sealed bedroom reads. A correctly sized purifier in a closed room can pull a room far below the outdoor number; an undersized one in a room with an open door cannot. The GRAP stages explained guide covers what the city restrictions at each level mean.
AQI Number vs PM2.5 in µg/m³
This is the most common source of confusion. AQI and PM2.5 are two different scales. PM2.5 is a concentration: micrograms of fine particles in a cubic metre of air (µg/m³). AQI is an index: a 0 to 500 number calculated from that concentration (and from other pollutants), designed so that people can read it at a glance.
- A monitor that shows “PM2.5: 60” and one that shows “AQI: 100” may be describing similar air. The numbers are not interchangeable.
- India’s AQI is built so that an index of 100 lines up with the 24-hour national standard for each pollutant. For PM2.5, that standard is 60 µg/m³.
- Some devices and apps use another country’s AQI formula. The same air can show a different AQI number on two screens, so check which scale your monitor or app uses before comparing.
When in doubt, look at the raw PM2.5 in µg/m³. It is the figure the health limits below are written in.
WHO and Indian Limits for PM2.5 and PM10
| Pollutant | WHO 2021 guideline | India NAAQS |
|---|---|---|
| PM2.5, 24-hour | 15 µg/m³ | 60 µg/m³ |
| PM2.5, annual | 5 µg/m³ | 40 µg/m³ |
| PM10, 24-hour | Not used in this guide | 100 µg/m³ |
| PM10, annual | Not used in this guide | 60 µg/m³ |
The WHO guideline is a health target: the level below which the evidence of harm is weakest. The Indian National Ambient Air Quality Standards (NAAQS) are the legal outdoor limits. The gap between the two is large, which is why an outdoor reading can be “within the national standard” and still be well above what the WHO recommends.
Why Indoor and Outdoor AQI Differ
Many people assume that closing the windows makes indoor air clean. It helps, but fine particles are small enough to travel through gaps around doors, windows, AC ducts and exhaust openings. Without filtration, indoor PM2.5 in a polluted city usually follows the outdoor level, with a lag.
Indoor air can also be worse than outdoor air for short spells, because a home has its own sources:
- Cooking, especially frying and tadka, without a chimney or exhaust running. See how Indian cooking affects indoor air.
- Agarbatti, dhoop, camphor and mosquito coils.
- Dust stirred up by sweeping, dusting and fans.
- Firecracker smoke drifting in around Diwali, covered in our Diwali smoke and indoor air guide.
And there is one thing a sealed room gets worse at: carbon dioxide from breathing builds up when windows stay shut. That is not a particle problem and a purifier does not fix it; a short airing when the outdoor air is at its cleanest does.
A Realistic Indoor Target
The WHO 24-hour figure of 15 µg/m³ is hard to hold through a north Indian winter, but it is the right direction. A practical ladder:
- Minimum: keep indoor PM2.5 below the 24-hour NAAQS of 60 µg/m³ in every room people use. On the Indian AQI that means staying at or under 100.
- Better: keep the bedroom in the Good band (AQI 50 or below) through the night, because that is where most hours of breathing happen.
- Best you can practically do: get the bedroom as close to the WHO 24-hour guideline of 15 µg/m³ as your room and purifier allow, especially for children, older relatives and anyone with a lung or heart condition.
Getting there is mostly a matter of sizing. A purifier needs enough Clean Air Delivery Rate (CADR) for the room’s volume, and the door needs to stay shut while it works. The air purifier size calculator gives you the CADR your room needs.
Boon Airvana shows a live AQI on its display and reads PM1.0, PM2.5 and PM10 every second, so you can see whether your bedroom is actually under 50, not just guess.
See Boon Airvana →How to Know Your Room’s Number
You cannot see or smell PM2.5 reliably, so a number is the only way to know. Two sources together give you the full picture:
- Outdoor: the AQI for your city tells you what is pressing on your windows today and whether a short airing makes sense.
- Indoor: a laser particle monitor or a purifier with a built-in PM sensor tells you what is in the room. Our guide on how to check air quality at home compares monitors, apps and what each can and cannot measure.
Check the reading at three moments: after cooking, late in the evening when outdoor pollution tends to settle low over cities, and first thing in the morning in the bedroom. If the morning bedroom reading is under 50, your setup is working.
If someone at home has persistent cough, wheezing or breathlessness during smog season, a low indoor AQI helps but it is not a treatment. See a doctor, and tell them about the air at home.
Frequently Asked Questions
What AQI level is safe inside a home?
An indoor AQI of 50 or below, the CPCB Good band, is the target. Between 51 and 100 is acceptable for most healthy people for short periods. Above 100, close windows during the worst hours, cut indoor smoke sources and run a correctly sized air purifier, especially in the bedroom. Children, older people and anyone with asthma or heart disease benefit most from keeping rooms under 50.
AQI kitna hona chahiye ghar ke andar?
Inside the home, AQI should ideally be 50 or less. Up to 100 is acceptable for a short time for healthy adults. If it is above 100 indoors, keep doors and windows shut during peak pollution, avoid incense and smoky cooking without the exhaust on, and run an air purifier sized for the room.
Is AQI the same as PM2.5?
No. PM2.5 is a concentration measured in micrograms per cubic metre. AQI is an index from 0 to 500 calculated from that concentration and other pollutants. On India’s AQI, an index of 100 lines up with the 24-hour PM2.5 standard of 60 µg/m³. Different apps may use different AQI formulas, so compare raw PM2.5 when you can.
Can indoor AQI be worse than outdoor AQI?
Yes, for short spells. Frying or tadka without an exhaust, agarbatti or dhoop, mosquito coils and sweeping can push indoor particle levels above the outdoor reading. In smog season, fine particles also seep in through gaps, so a closed home without filtration usually follows the outdoor level rather than staying clean.
What should I do if my room AQI is above 300?
Shut the door and windows of the room you are using, run an air purifier sized for that room on a high setting or Auto, and avoid any indoor smoke. Keep vulnerable family members in the cleanest room. If anyone has breathlessness, chest tightness or wheezing that does not settle, contact a doctor rather than relying on the purifier.
What PM2.5 level should I aim for indoors?
At minimum, keep indoor PM2.5 below 60 µg/m³, the Indian 24-hour standard. A better goal for the bedroom is the Good AQI band. The health-based target is the WHO 24-hour guideline of 15 µg/m³; it is hard to hold all winter, but getting the bedroom close to it is a reasonable aim with a correctly sized purifier and a closed door.
Want to see your bedroom’s AQI every second instead of guessing? Boon Airvana reads PM1.0, PM2.5 and PM10 and shows a live AQI on its display.
See Boon Airvana →