Report · 04 September 2026

145 AQI at Wazirpur, 24 hours to 4 PM, 04 September 2026, the worst monitor in Delhi today, Moderate on CPCB's documented formula, and PM10 set that figure. 14.0 lakh people live within 4 km of it.

77.3

TODAY

Delhi's AQI calculated with CPCB's documented formula, the mean of 43 stations.

55.9 lakh

NEAR MODERATE OR WORSE

Within 4 km of 6 Moderate-or-worse monitors: 26.7 per cent of Delhi, every pollutant counted.

1.5x

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, 4.0 MB

The day in brief

Today, 04 September 2026, 24 hours to 4 PM: Delhi's AQI was 77.3, Satisfactory, calculated with CPCB's documented formula as the mean of 43 stations' AQIs (CPCB's note "How is AQI calculated?" and its AQI Calculator; page 33 sets out the formula). As measured, 37 of the 43 monitors reading PM2.5 were above the WHO 24-hour guideline of 15 µg/m³. 6 of 43 monitors read Moderate or worse on CPCB's documented formula, and 55.9 lakh people, 26.7 per cent of Delhi, live within 4 km of one.

The year so far, 1 January to 4 September: the cleaner days of 2026 have been the dirtiest for these dates since 2019, because three days in four read above 109.2 on the particle AQI, against 89.0 on the same dates of 2025. The middle day reads 156.8 against 146.5 on the same dates last year. On an average day, 30.1 per cent of Delhi's reporting monitors, about 12 of 43, sat above 200 on the particle AQI.

The findings

What the report says

Against yesterday: the one-day move

From 78 to 77. On the 43 stations that reported on both days, the 95 per cent interval runs -10.7 to 6.6 points, so the honest reading is level, not better.

Against last year: the observed reading

Today 77 across 43 stations. The year is judged on the 35 matched stations: 80 today against 83, the mean of the same date ±7 days of 2025 at those stations. The interval runs -9 to 4.3 points, so the honest reading is level, not better.

The worst station in the city today

Moderate, set by PM10. Its PM10 averaged 160.7 µg/m³ over the 24 hours to 4 PM, 3.5 times the WHO 24-hour guideline of 45 µg/m³. Last year this station read 126 on the mean of the same date ±7 days, so the change is +18.8 points. 14.0 lakh people live within 4 km of this monitor. Within 500 m of the monitor, 91% of the land is built up and 8% is under vegetation, so this reading describes a densely built neighbourhood.

The year, from its best days to its worst

On the same 247 complete dates, 1 January to 4 September, the best tenth of days reads 81.7 against 71.7 and the worst tenth 301.3 against 303.1. The days at or below 200 went from 171 to 169.

How much of the city was above AQI 200

That is 12.5 of 43.2 reporting stations, against 28.5 per cent over the same dates last year, a change of +1.6 points on an interval of -4.1 to +7.7, 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 45 per cent, and within 500 m only 3.6 per cent. Delhi has 55 monitors in 53 zones, of which 43 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 26.7 per cent of Delhi, living around the 6 monitors that read Moderate or worse. No monitor read Poor or worse today. Wazirpur was worst at 145, and 14.0 lakh people live within 4 km of it.

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