Air Quality Check for India

The six official AQI categories

CPCB’s 2014 methodology defines six bands with specific health impact descriptions:

• 0–50 Good (green). Minimal impact. Air quality you wouldn’t notice. Most of coastal Karnataka, the Western Ghats, Himachal in summer.
• 51–100 Satisfactory (light green). Minor breathing discomfort for sensitive people. Most of South India outside major industrial belts.
• 101–200 Moderate (yellow). Breathing discomfort for people with lung, asthma, or heart conditions. The annual baseline for most Tier-1 Indian cities.
• 201–300 Poor (orange). Breathing discomfort for most people on prolonged exposure. NCR for half the year. Industrial corridors around Patancheru, Manali, Vapi.
• 301–400 Very Poor (red). Respiratory illness on prolonged exposure. NCR in winter. Mid-Gangetic plain in stubble-burning season.
• 401–500 Severe (maroon). Affects healthy people; serious for vulnerable groups. Delhi and NCR for 30–60 days a year, October through February.

Which pollutants matter, and what each one tells you

The AQI is whichever pollutant is worst at a given moment. Knowing which one is dominant tells you where the pollution is coming from.

• PM2.5 — fine particles under 2.5 micrometres. The most damaging long-term, because they reach deep into lung tissue. Source: vehicle exhaust, industrial combustion, biomass and stubble burning, construction dust. If PM2.5 is dominant, you are near a road, a factory, or downwind of large-scale biomass burning.
• PM10 — particles under 10 micrometres. More visible than PM2.5, larger fraction is local. Source: road dust, construction, mining. PM10-dominant typically means a construction zone or unsealed road within 1–2 km.
• NO₂ — nitrogen dioxide. Source: vehicle exhaust at scale. NO₂-dominant means very high traffic density — typically an arterial road or major junction within 500 m.
• SO₂ — sulphur dioxide. Source: coal-fired power plants, refineries, heavy industry burning sulphur-rich fuel. SO₂-dominant means a coal plant, refinery, or heavy industrial plant within 15–20 km.
• CO — carbon monoxide. Source: incomplete combustion (fires, biomass, faulty engines). Rarely dominant; when it is, look for active biomass burning or a major combustion source nearby.
• O₃ — ground-level ozone. Not directly emitted — forms when NOx and VOCs react in sunlight. Ozone-dominant readings are typical of hot urban afternoons in summer.

The Indian seasonal swing

Air quality in India is not constant through the year. Two reasons it changes:

Stubble burning. From mid-October through November, farmers across Punjab and Haryana burn crop residue to clear fields for the next planting. The resulting PM2.5 plume crosses the Indo-Gangetic plain and parks itself over NCR, UP, and Bihar for 6–8 weeks. AQI in Delhi commonly jumps from 150 (October 1) to 400+ (November 1).

Atmospheric mixing layer height. In summer, hot air rises and disperses pollutants vertically up to 2–3 km. In winter, cold dense air sits near the ground and the mixing layer drops to 200–400 m — pollutants accumulate in a much thinner slab. The same emissions produce 3–5× higher ground-level concentrations.

The combined effect: most North Indian cities are 3–5× worse from October to February than from May to August. A buyer who visits Delhi in March and signs in March will be surprised by November.

Why the 12-month average matters more than today’s number

Today’s AQI swings with the weather. A windy afternoon in Lucknow can read “Good” in November while the actual seasonal baseline is “Very Poor”. For a buyer making a 30-year decision, the 12-month average is the comparable number across plots. A plot that averages 95 AQI year-round is meaningfully different from one that averages 220 — even if both happen to read “Moderate” on the day you visit.

This is why our result card shows three numbers, not one: today’s interpolated AQI, the 12-month average, and the 3-year trend (Improving / Stable / Worsening). The trend tells you whether things are getting better or worse — a critical signal for any long-hold land investment.

India urban planning context

NCR (Delhi, Gurgaon, Noida, Ghaziabad) — annual average AQI typically 180–220. Winter months routinely 350+. The single most polluted urban region in India by margin.

Industrial belts — Patancheru (west of Hyderabad), MIDC belt (around Pune and Aurangabad), Manali (north of Chennai), Vapi (south of Surat). Annual averages 140–180; SO₂ and PM10 often dominant.

Coastal cities — Mangalore, Visakhapatnam, Chennai’s coastal belt, Mumbai’s western suburbs. Sea breeze dispersion keeps annual averages in the 80–120 range — Satisfactory to Moderate.

Bengaluru and Hyderabad — annual averages 100–140 in city centre; suburbs and tech corridors typically 80–120. Cleaner than NCR, dirtier than coastal cities. Both worsening year on year.

Hill towns — Dehradun, Shimla, Munnar, Coorg, Wayanad. Annual averages under 80 — Good to Satisfactory most of the year. The cleanest large category in India.

Why this matters for property value

Air quality is no longer a soft preference; it has become a measurable driver of residential demand. In NCR, properties in worst-affected micro-pockets (heavy industrial fringes, near landfills, downwind of brick kilns) show 10–25% absorption lag versus comparable plots in better-ventilated zones. New-build projects increasingly advertise their distance from the nearest CPCB station with high readings. Long-term exposure to PM2.5 above 60 µg/m³ is linked to documented respiratory and cardiovascular disease — this is a health cost, not just a comfort issue, and serious buyers now check it.