India's air quality crisis is a year-round public health emergency. Delhi's winter AQI routinely exceeds 400 (hazardous). But even cities that rarely make headlines — Lucknow, Patna, Agra, Muzaffarpur — have annual average pollution levels far above WHO safe limits.

Understanding AQI

The Air Quality Index measures fine particulate matter (PM2.5), coarser particles (PM10), ozone, nitrogen dioxide and other pollutants. PM2.5 — particles smaller than 2.5 micrometres — is most dangerous because it enters the bloodstream directly through the lungs. Good: 0–50. Satisfactory: 51–100. Moderate: 101–200. Poor: 201–300. Very Poor: 301–400. Severe: 400+.

Check real-time AQI on CPCB's Sameer app or AQI India (aqicn.org). Build it into your daily routine the way you check the weather.

Outdoor Protection

When AQI exceeds 150, wear an N95 or N99 mask — not a cloth or surgical mask, which does not filter PM2.5. N95s filter 95% of particles; KN95s are broadly equivalent. Cost: ₹80–₹200 per mask. Avoid outdoor exercise when AQI is above 100 — physical exertion increases your breathing rate and therefore your pollution intake dramatically.

Indoor Air Quality

Indoor air is often 2–5 times more polluted than outdoor air due to cooking smoke, incense, cleaning products and infiltration of outdoor pollutants. An air purifier with a HEPA filter dramatically reduces PM2.5 indoors. Options at every budget: IQAir (₹30,000+, best performance), Dyson (₹35,000+), Xiaomi Mi Air Purifier 4 Pro (₹13,000 — excellent value), Coway (₹12,000–₹18,000).

Keep windows closed on high-pollution days. Cook with the exhaust fan on. Replace incense sticks with essential oil diffusers. These changes meaningfully reduce daily exposure.

Long-Term Health Effects of Chronic Exposure

Long-term PM2.5 exposure is linked to chronic obstructive pulmonary disease, lung cancer, cardiovascular disease, and reduced cognitive development in children. Children, elderly, pregnant women and those with existing lung or heart conditions are most vulnerable. These groups should take protection especially seriously.