Report · 21 October 2026

362 AQI at Pusa (IITM), 24 hours to 4 PM, 21 October 2026, the worst monitor in Delhi today, Very Poor on CPCB's documented formula, and PM2.5 set that figure. 11.5 lakh people live within 4 km of it. The second monitor at Pusa, Pusa (DPCC), read 315.

264.3

TODAY

Delhi's AQI calculated with CPCB's documented formula, the mean of 57 stations.

1.91 crore

NEAR POOR OR WORSE

Within 4 km of 42 Poor-or-worse monitors: 84.5 per cent of Delhi, every pollutant counted.

8.3x

THE WHO 24-HOUR LINE

Delhi's PM2.5 today, as measured, against the WHO 24-hour guideline.

The AQI figures here are calculated with the formula that the Central Pollution Control Board (CPCB) publishes for its air quality index. CPCB's own documents set out that formula: CPCB's note on how the AQI is calculated; CPCB's AQI calculator.

The full report

The complete written report for this day, with every figure and the source it comes from.

Download the daily reportPDF, 4.7 MB

The day in brief

Today, 21 October 2026, 24 hours to 4 PM: Delhi's AQI was 264.3, Poor, calculated with CPCB's documented formula as the mean of 57 stations' AQIs (CPCB's note "How is AQI calculated?" and its AQI Calculator; page 34 sets out the formula). As measured, 44 of the 44 monitors reading PM2.5 were above the WHO 24-hour guideline of 15 µg/m³. Above AQI 200 today: 42 stations, Pusa (IITM) 362, Chandni Chowk 360, Punjabi Bagh 356, Jahangirpuri 340, and 38 more in the station table. Poor or worse air reached 1.91 crore people within 4 km of their monitor today, 84.5 per cent of Delhi.

The year so far, 1 January to 20 October: the cleaner days of 2026 have been the dirtiest for these dates since 2019, because three days in four read above 106.7 on the particle AQI, against 91.6 on the same dates of 2025. The middle day reads 152.8 against 139.5 on the same dates last year. On an average day, 26.7 per cent of Delhi's reporting monitors, about 11 of 44, sat above 200 on the particle AQI.

The findings

What the report says

Against yesterday: the one-day move

From 181 to 265. On the 55 stations that reported on both days, the 95 per cent interval runs 71.7 to 97.3 points.

Against last year: the observed reading

Today 264 across 57 stations. The year is judged on the 38 matched stations: 287 today against 306, the mean of the same date ±7 days of 2025 at those stations. The interval runs -39.8 to 1 points, so it leans better, but the interval spans zero and no claim is made.

The worst station in the city today

Very Poor, set by PM2.5. Its PM2.5 averaged 200.5 µg/m³ over the 24 hours to 4 PM, 13.3 times the WHO 24-hour guideline of 15 µg/m³. Last year this station read 284 on the mean of the same date ±7 days, so the change is +77.7 points. It is one of the two monitors at Pusa; the second, Pusa (DPCC), read 315. 11.5 lakh people live within 4 km of this monitor. Within 500 m of the monitor, 54% of the land is built up and 46% is under vegetation, so this reading describes a mixed neighbourhood.

The year, from its best days to its worst

On the same 293 complete dates, 1 January to 20 October, the best tenth of days reads 75.7 against 72.1 and the worst tenth 286.8 against 295.1. The days at or below 200 went from 211 to 214.

How much of the city was above AQI 200

That is 11.2 of 43.7 reporting stations, against 26.5 per cent over the same dates last year, a change of +0.2 points on an interval of -5.7 to +5.7, so it is unchanged inside its margin.

Who the monitoring network reaches

Within 4 km live 92 per cent of Delhi's people, within 2 km 44 per cent, and within 500 m only 3.5 per cent. The map holds 55 monitors in 53 zones; 57 monitors reported today. 33 of the 53 zones stretch past our chosen 4 km proximity threshold, informed by US EPA neighbourhood-scale guidance.

What each monitor's reading speaks for

That is 84.5 per cent of Delhi, living around the 42 monitors that read Poor or worse. Pusa (IITM) was worst at 362, and 11.5 lakh people live within 4 km of it. This counts people near the monitors, not measured individual exposure.

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