Report · 31 August 2026

228 AQI at Wazirpur, 24 hours to 4 PM, 31 August 2026, the worst monitor in Delhi today, Poor on CPCB's documented formula, and PM10 set that figure. 14.0 lakh people live within 4 km of it.

119

TODAY, AS MEASURED

Measured on CPCB's documented formula; with the weather removed, the model's 41 stations read 82, against 119 measured.

1.77 crore

NEAR MODERATE OR WORSE

Within 4 km of 33 Moderate-or-worse monitors: 84.5 per cent of Delhi, every pollutant counted.

1.9x

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, 31 August 2026, 24 hours to 4 PM: worse than last year on the observed index, +47.5 points; with the weather removed, still 0.8 points worse on the model's count. 2 of 3 pollutants, PM2.5, PM10, show no real improvement. Delhi's AQI was 119.2, Moderate, calculated with CPCB's documented formula as the mean of 41 stations' AQIs (CPCB's note "How is AQI calculated?" and its AQI Calculator; page 33 sets out the formula). As measured, 38 of the 41 monitors reading PM2.5 were above the WHO 24-hour guideline of 15 µg/m³. Poor or worse air reached 14.0 lakh people within 4 km of their monitor today, 6.7 per cent of Delhi.

The year so far, 1 January to 31 August: the cleaner days of 2026 have been the dirtiest for these dates since 2019, because three days in four read above 112.4 on the particle AQI, against 92.2 on the same dates of 2025. The middle day reads 158.1 against 147.2 on the same dates last year. On an average day, 30.6 per cent of Delhi's reporting monitors, about 13 of 43, sat above 200 on the particle AQI.

The findings

What the report says

The verdict, both rulers

On the weather model's own count of 33 matched stations, the observed year reads +52 points; with the weather removed it is still +0.8 points worse, on the model's count across 24 of 33 stations. 2 of 3 pollutants, PM2.5, PM10, show no real improvement. With the weather removed, 24 of the model's 33 matched stations read higher than last year.

Against yesterday: the one-day move

From 125 to 119. On the 41 stations that reported on both days, the 95 per cent interval runs -10.8 to -2.5 points.

Against last year: the observed reading

Today 119 across 41 stations. The year is judged on the 33 matched stations: 122 today against 74, the mean of the same date ±7 days of 2025 at those stations. The interval runs 39.6 to 55.5 points.

The worst station in the city today

Poor, set by PM10. Its PM10 averaged 278.3 µg/m³ over the 24 hours to 4 PM, 6.1 times the WHO 24-hour guideline of 45 µg/m³. Last year this station read 113 on the mean of the same date ±7 days, so the change is +114.9 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 243 complete dates, 1 January to 31 August, the best tenth of days reads 83.1 against 72.5 and the worst tenth 301.8 against 305.9. The days at or below 200 went from 167 to 165.

How much of the city was above AQI 200

That is 12.7 of 43.2 reporting stations, against 29.0 per cent over the same dates last year, a change of +1.6 points on an interval of -4.0 to +7.9, 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 41 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 6.7 per cent of Delhi, living around the 1 monitor that read Poor or worse. Wazirpur was worst at 228, and 14.0 lakh people live within 4 km of it. On the wider count, 1.77 crore people, 84.5 per cent of Delhi, live within 4 km of a monitor at Moderate or worse.

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