Quick answer: pollution season has started. Delhi’s air turned “poor” (AQI 245) on 21 October, the first time this season, and authorities have invoked GRAP Stage I across Delhi-NCR. You can’t fix the air outside, but you can make the air you breathe at home, at work and on your commute much cleaner. Here is a practical, no-panic guide with air pollution tips that actually work: what the AQI numbers mean, which air purifier and mask to pick, and the daily habits that make the biggest difference.
Where things stand this week
- Delhi’s 24-hour AQI jumped from 179 to 245 on 21 October, its worst post-Dussehra reading in five years.
- Several stations crossed 300 (“very poor”), including Pusa (329), Chandni Chowk (326) and Jahangirpuri (313). In the NCR, Greater Noida hit 280.
- Forecasters expect air to stay “poor” in the coming days, and the share of pollution from stubble burning is expected to rise this week.
- Under GRAP Stage I, open burning of waste is banned, dust control rules are tighter and older non-BS-VI interstate buses face entry curbs. Delhi Metro is adding extra trips.
This guide is written with Delhi-NCR in mind, but it applies to any city where winter air gets bad, including Lucknow, Patna, Kanpur and parts of Punjab and Haryana.
First, understand the AQI number
India’s Air Quality Index (set by the Central Pollution Control Board) runs from 0 to 500. Here is what each band means for your day:
| AQI | Category | What to do |
|---|---|---|
| 0–50 | Good | Open windows, enjoy outdoors |
| 51–100 | Satisfactory | Normal routine |
| 101–200 | Moderate | Sensitive people take it easy outdoors |
| 201–300 | Poor | Cut long outdoor workouts, run purifier |
| 301–400 | Very poor | Exercise indoors, mask outdoors, windows shut |
| 401–500 | Severe | Stay indoors as much as possible |
Tip: the city-wide number is an average. Your street can be much better or worse. Check the station nearest to you on the SAMEER app from CPCB, or on free sites like aqi.in or IQAir, before you plan a walk or run.
1. Make one room a “clean air room”
You don’t need to purify the whole house. Most of us spend 7–9 hours a night in the bedroom, so start there.
- Seal the gaps. Keep windows shut on bad days and use draught strips or a rolled towel at the bottom of doors and old window frames.
- Run a purifier with the door closed. A purifier in a sealed room works far better than one fighting air coming in from the whole flat.
- Ventilate smartly. Rooms still need fresh air. Open windows for 10–15 minutes when the outdoor AQI is at its lowest, which is usually early-to-mid afternoon in winter, then close them again.
2. How to choose an air purifier (without overspending)
Ignore marketing words like “ionic”, “plasma” or “99.99% germs”. Look at three things:
- A true HEPA filter (H13 or similar). This is what actually catches PM2.5, the fine dust that causes the most harm.
- CADR (Clean Air Delivery Rate) that matches your room. A common rule of thumb: the CADR in cubic feet per minute (CFM) should be at least two-thirds of the room’s area in square feet. For a 150 sq ft bedroom, look for a CADR of 100 CFM or more. For Delhi’s worst weeks, go higher.
- Filter cost and availability. Check the price of replacement filters before you buy. A cheap purifier with expensive or hard-to-find filters costs more in the long run.
Avoid: purifiers that produce ozone. Ozone itself irritates the lungs.
On a tight budget? Try a DIY box-fan filter
Researchers and engineers have popularised the Corsi-Rosenthal box: four or five MERV-13 (or similar) furnace filters taped into a cube with a box fan on top, blowing outwards. Tests in the US found these can clean a room’s air very effectively for a fraction of the price of a branded purifier. In India, the filters can be harder to find, but they are available online. It is noisy and not pretty, but it works.
3. Wear the right mask, the right way
- Use an N95 or FFP2 mask on “poor” days and worse. Cloth masks and loose surgical masks do little against PM2.5.
- Fit matters more than brand. Pinch the metal strip around your nose and make sure there are no gaps at the sides. If your glasses fog up, air is leaking.
- Valve masks are fine for pollution (they protect the wearer), but they don’t filter the air you breathe out.
- Replace them when they get damp, dirty, or harder to breathe through. Don’t wash disposable N95s.
4. Rethink your exercise routine
You breathe much more air, and more deeply, when you run or cycle. On bad days that means more pollution in your lungs.
- Skip the early-morning run when AQI is poor. In winter, cold air near the ground traps pollution at dawn and late at night (a “temperature inversion”).
- Move workouts indoors: skipping, bodyweight circuits, yoga, stairs, or a gym with good filtration.
- Walk away from traffic. Even a street or two away from a main road can mean noticeably cleaner air.
5. Clean up your commute
- In a car: keep windows up and set the AC to recirculate. Change the cabin air filter if it hasn’t been replaced in a year; some cars accept a PM2.5 cabin filter.
- On a two-wheeler or walking: a well-fitted N95 is your main protection.
- Use the Metro where you can. It cuts your exposure in traffic and the number of vehicles on the road.
6. Stop polluting your own home
Some of the worst air you breathe is made indoors:
- Cooking smoke: use the chimney or exhaust fan every time you fry or use a tadka, and keep it on for a few minutes after.
- Incense, mosquito coils and candles release fine particles. Cut down on bad-air days.
- Dust: wet-mop floors and damp-wipe surfaces instead of dry sweeping, which throws dust back into the air.
- Never smoke indoors.
Myths to ignore
- “Indoor plants will clean the air.” Plants are lovely, but studies show you would need an impossible number of them per room to match even basic ventilation or a purifier.
- “Pollution is only bad if you can see smog.” PM2.5 particles are invisible. A clear-looking day can still have poor AQI, so check the number.
- “A handkerchief over the nose is enough.” It may stop large dust, but not the fine particles that matter.
Who needs to be extra careful
Children, older people, pregnant women and anyone with asthma, COPD or heart disease are more sensitive to polluted air. If someone in your family falls in these groups, give them the clean-air room, keep their medicines handy, and talk to a doctor if symptoms like breathlessness, persistent cough or chest tightness get worse.
Your 5-minute pollution season checklist
- Install SAMEER or another AQI app and set your nearest station
- Pick one clean-air room and seal its gaps
- Get a HEPA purifier sized for that room, or build a DIY box-fan filter
- Stock a few well-fitting N95 or FFP2 masks
- Move workouts indoors on “poor” days and worse
- Set the car AC to recirculate and check the cabin filter
Frequently asked questions
What is Delhi’s AQI today?
It was 245 (“poor”) in the 21 October bulletin and is expected to stay in the poor range for the next few days. Check the SAMEER app or CPCB’s website for live readings at your nearest station.
What is GRAP Stage I?
GRAP (Graded Response Action Plan) is Delhi-NCR’s emergency plan for bad air. Stage I applies when AQI is “poor” and covers measures like a ban on open waste burning, dust control at construction sites and curbs on older interstate buses. Stricter stages follow if AQI gets worse.
Do air purifiers really work?
Yes, a true HEPA purifier of the right size noticeably lowers PM2.5 indoors, especially in a closed room. Pick one by CADR and room size, not by marketing claims.
When is the best time to go outside during pollution season?
In winter, air is often cleanest in the early-to-mid afternoon and worst at dawn and late at night. Check your local AQI before heading out.
This article is general information, not medical advice. If you or a family member has a heart or lung condition, follow your doctor’s guidance.
Sources: Outlook India; Business Today; Deccan Herald; Central Pollution Control Board AQI categories. Air quality figures as of 21–22 October 2026.
