Report · 04 October 2026

291 AQI at Dwarka-Sector 8, 24 hours to 4 PM, 04 October 2026, the worst monitor in Delhi today, Poor on CPCB's documented formula, and PM10 set that figure. 8.0 lakh people live within 4 km of it.

185.1

TODAY

Delhi's AQI calculated with CPCB's documented formula, the mean of 44 stations.

1.71 crore

NEAR MODERATE OR WORSE

Within 4 km of 44 Moderate-or-worse monitors: 82.0 per cent of Delhi, every pollutant counted.

4.3x

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, 3.9 MB

The day in brief

Today, 04 October 2026, 24 hours to 4 PM: Delhi's air today is 67 points worse than on this date last year, which is 54.4 per cent higher, and 14.7 points worse than yesterday, on the Central Pollution Control Board's own readings. Delhi's AQI was 185.1, Moderate, calculated with CPCB's documented formula as the mean of 44 stations' AQIs (CPCB's note "How is AQI calculated?" and its AQI Calculator; page 32 sets out the formula). Above AQI 200 today: 15 stations, Dwarka-Sector 8 291, Mundka 289, CRRI Mathura Road 256, Narela 254, and 11 more in the station table. Poor or worse air reached 1.24 crore people within 4 km of their monitor today, 59.4 per cent of Delhi.

The year so far, 1 January to 4 October: the cleaner days of 2026 have been the dirtiest for these dates since 2018, because three days in four read above 106.1 on the particle AQI, against 89.8 on the same dates of 2025. The middle day reads 149.5 against 134.9 on the same dates last year. On an average day, 27.3 per cent of Delhi's reporting monitors, about 11 of 43, sat above 200 on the particle AQI.

The findings

What the report says

Against yesterday: the one-day move

From 171 to 185. On the 43 stations that reported on both days, the 95 per cent interval runs 8.3 to 21.2 points.

Against last year: the observed reading

Today 185 across 44 stations. The year is judged on the 37 matched stations: 190 today against 123, the mean of the same date ±7 days of 2025 at those stations. The interval runs 56.6 to 78.1 points.

The worst station in the city today

Poor, set by PM10. Its PM10 averaged 341.4 µg/m³ over the 24 hours to 4 PM, 7.5 times the WHO 24-hour guideline of 45 µg/m³. Last year this station read 143 on the mean of the same date ±7 days, so the change is +148.4 points. 8.0 lakh people live within 4 km of this monitor. Within 500 m of the monitor, 65% of the land is built up and 34% is under vegetation, so this reading describes a densely built neighbourhood.

The year, from its best days to its worst

On the same 277 complete dates, 1 January to 4 October, the best tenth of days reads 74.4 against 72.0 and the worst tenth 291.2 against 290.9. The days at or below 200 went from 201 to 199.

How much of the city was above AQI 200

That is 11.4 of 43.2 reporting stations, against 25.7 per cent over the same dates last year, a change of +1.6 points on an interval of -3.4 to +6.8, 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 45 per cent, and within 500 m only 3.6 per cent. Delhi has 55 monitors in 53 zones, of which 44 reported today, and 30 of the 53 zones stretch past 4 km, the distance that the US EPA's neighbourhood scale treats as the furthest a monitor speaks for.

What each monitor's reading speaks for

That is 59.4 per cent of Delhi, living around the 15 monitors that read Poor or worse. Dwarka-Sector 8 was worst at 291, and 8.0 lakh people live within 4 km of it. On the wider count, 1.71 crore people, 82.0 per cent of Delhi, live within 4 km of a monitor at Moderate or worse.

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