AQI levels in India explained — what to do at each band (with health advice)

Quick answer: India's National Air Quality Index uses six bands: Good (0-50), Satisfactory (51-100), Moderate (101-200), Poor (201-300), Very Poor (301-400), and Severe (401+). The action you should take changes dramatically across these bands. Below 100, breathe normally. Above 200, sensitive groups should mask up. Above 400, treat the day as an indoor-only day.

If you live in any major Indian city, the AQI affects your daily decisions — whether to walk, run outside, send kids to school, open the bedroom window, run a purifier. This guide tells you exactly what to do at each level.

The six AQI bands and what they mean

Good (0–50) — green zone

Air quality is satisfactory and poses little or no risk.

What to do: open all windows. Run, walk, exercise outdoors freely. Skip the air purifier. Send kids to play. This is what air quality should be like every day — and is, in most of southern and coastal India for most of the year.

Satisfactory (51–100) — light green

Minor breathing discomfort possible for very sensitive individuals.

What to do: outdoor activity is fine for healthy adults. Asthmatics keep their inhaler nearby but don't change routine. The air is technically polluted but not at a level that affects most people.

Moderate (101–200) — yellow

Breathing discomfort likely for people with lung disease, heart disease, children, the elderly.

What to do:

• Sensitive groups: limit prolonged outdoor exertion. Use an N95 mask if you'll be outside for more than 30 minutes.
• Healthy adults: outdoor activity OK but consider not running outside for more than 45 minutes.
• Run an air purifier indoors if the level stays above 150 for multiple days.
• Schools: outdoor sport for younger kids should move indoors.

Poor (201–300) — orange

Breathing discomfort to most people on prolonged exposure.

What to do:

• Sensitive groups: stay indoors. N95 mask if you must go out. Skip morning walks.
• Healthy adults: minimise outdoor activity. Cancel any outdoor running or cycling. Use N95 outside.
• Indoor: keep windows closed. Run purifier all day. Use exhaust fans during cooking.
• Schools: cancel outdoor sport entirely. Move PE indoors.
• This is typical Delhi NCR Oct-Feb — and most NCR residents underestimate the cumulative damage.

Very Poor (301–400) — red

Respiratory illness on prolonged exposure for everyone.

What to do:

• Stay indoors as much as possible. Work from home if your job allows.
• Air purifier on full power throughout the day. Keep all windows shut.
• N95 mask is mandatory if you must go out — even to the parking lot.
• Elderly, asthmatics, COPD/heart patients: minimise exposure. If you start coughing or feeling tightness in chest, see a doctor.
• Schools should suspend outdoor activities entirely; many schools shut down in NCR at these levels.
• Pregnant women: avoid going outside for extended periods. Air pollution at this level has documented effects on birth weight and pre-term delivery.

Severe (401+) — maroon

Affects healthy people; serious impact on those with heart/lung disease.

What to do:

• Treat as a health emergency for sensitive groups.
• Stay indoors with purifiers running.
• WFH if at all possible.
• N95 mandatory for any outdoor exposure.
• Schools should suspend outdoor activity completely; many close.
• Government may invoke emergency response measures (GRAP IV in NCR).
• This level happens occasionally in Delhi NCR during winter inversions, and during diwali / stubble-burning season.

Why N95 — and what masks actually filter

PM2.5 (fine particulate matter, the most damaging Indian air pollutant) has a diameter under 2.5 microns. To physically block it, you need:

• N95 / KN95 / FFP2 — ~95% filtration of 2.5-micron particles. Best for daily use. ₹150-400 each in India, reusable for 2-3 weeks.
• N99 / FFP3 — ~99% filtration. Useful at AQI 400+. Heavier and harder to breathe through.

Don't bother with:

• Surgical masks — designed to block droplets, not particles. ~30% filtration of PM2.5 at best.
• Cloth masks — almost no filtration of PM2.5.
• Bandanas / gamcha — symbolic only.

Indoor air can save you — if you set it up right

On a 350 AQI day in Delhi, indoor PM2.5 in a typical urban apartment can still hit 150 because:

• Cracks under doors and around windows leak in particles
• Kitchen exhausts pull in polluted outdoor air
• People returning home bring in particles on clothes
• Some HVAC systems just circulate without filtering

A HEPA air purifier sized for your room (CADR ≈ 5× room area in m²) can drop indoor PM2.5 to under 35 even on the worst Delhi days. The good Indian options:

• Mi Air Purifier 4 (~₹10k) — small rooms
• Honeywell Air Touch P2 (~₹15-18k) — medium rooms
• Sharp / Daikin / Blueair Pro models (₹25-50k) — large rooms

Health damage by AQI exposure

Sustained exposure to high AQI levels has documented effects:

• AQI 100-200 sustained: ~2-3 year reduction in life expectancy in heavily affected populations
• AQI 200+ sustained: increased risk of asthma in children, COPD in older adults, lung cancer
• AQI 400+ episodes: short-term spikes in heart attacks, strokes, hospital admissions
• Pregnant women: higher AQI correlates with lower birth weight

Indians living in NCR for 10+ years have an average reduction in life expectancy of ~7-9 years vs the country average, primarily from air pollution. This is real, measurable, and worth taking seriously.

Use the AQI tracker

The India AQI tracker shows live AQI for major cities, the band you're in, and the recommended action. Use it before stepping out for a run, opening windows in the evening, or deciding whether to send kids to outdoor sport.

FAQ

Q. What is "PM2.5" exactly? A. Particulate matter under 2.5 micrometres in diameter. Small enough to penetrate deep into lungs and even cross into the bloodstream. The dominant Indian air pollutant in winter, primarily from vehicles, industry, biomass burning and stubble burning.

Q. Why is Delhi's AQI so high in winter? A. Three factors: (1) atmospheric inversion in cold weather traps pollutants near the ground, (2) stubble burning in Punjab and Haryana adds 30-40% to base levels in October-November, (3) Delhi has dense vehicle and industrial emissions that have nowhere to go when the air is still.

Q. Are AQI numbers lower in monsoon? A. Yes — heavy rain physically washes pollutants out of the air. NCR's AQI in July-September often drops to 80-120 (Satisfactory to Moderate) after rain, the only time of year when it's consistently in green-yellow.

Q. Should I run outdoors at AQI 150? A. For healthy adults, occasionally yes; daily, no. The cumulative damage of running 60 minutes through AQI 150 every day adds up. Switch to a treadmill on bad days, especially in winter.

Q. Are AQI apps accurate? A. CPCB-sourced data (the official source) is reliable. Third-party sources like AQICN and IQAir use official monitors plus crowdsourced sensors and are usually accurate to within ±20 AQI points. The big problem is the sparse network — your specific neighbourhood may have very different AQI than the nearest monitor reports.