Delhi air quality drops to ‘poor’ category ahead of Diwali with 201 AQI

Delhi enjoyed a long streak of moderate air quality since June 11 when it recorded an AQI of 245.

Delhi's clean air streak is headed for a break ahead of Diwali as Centre’s Air Quality Early Warning System (EWS) predicts the Air Quality Index to slip into “poor” category this week.

A view of skyscrapers covered in haze due to rising air pollution levels in Delhi-NCR. (HT Photo )

On Tuesday morning, national capital's AQI has already slipped into poor category with a reading of 201.

This is the first instance of “poor” air quality in the national capital since June 11, when Delhi last recorded an AQI of 245.

“Delhi’s air quality is very likely to be in the ‘poor’ category from October 14 till October 16. The outlook for the subsequent six days shows the air quality is likely to be between the ‘poor’ to ‘very poor’ category,” EWS projections released on Monday said.

Delhi recorded a “moderate” AQI at 169 on Monday at 9am, the Central Pollution Control Board (CPCB) said. The 24-hour average air AQI touched 189 at 4pm. This was up 22 points from an AQI of 167 (moderate) on Sunday.

The outlook for the subsequent six days shows the air quality is likely to be between the ‘poor’ to ‘very poor’ category,” EWS projections released on Monday said.

The Capital has enjoyed 124 straight days of cleaner air – 77 of them “satisfactory”, and 47 “moderate” – since June 11, according to CPCB data. But with the monsoon withdrawal, falling temperatures, and the onset of stubble burning and festive emissions, experts say the familiar smog season has begun.

CPCB classifies air quality as “good” when the AQI is 0–50, “satisfactory” when it is 51–100, “moderate” between 101 and 200, “poor” 201–300, “very poor” 301–400, and “severe” 401–500.

Mahesh Palawat, vice president at Skymet meteorology told HT that wind speed has reduced, oscillating between 6-10 km/hr through Monday. “Wind direction is westerly to northwesterly and there will be marginal stubble intrusion. We don’t expect significant change in terms of weather, with similar wind direction and low wind speed to persist,” Palawat said.

Stubble burning, however, is not yet behind the spike in pollution. Data from the Decision Support System (DSS) – a model which calculates the estimated contribution of sources of pollution to Delhi’s PM 2.5 – showed that stubble burning accounted for just 0.62% of Delhi’s PM2.5 concentration on Monday – up slightly from 0.24% the previous day.

Meanwhile, Delhi government announced to declare the 41-kilometre area of the Southern Ridge will be a "Reserved Forest", which will significantly increase Delhi's green cover and improve air quality.

Chief Minister Rekha Gupta took to her X and stated that the Delhi government has taken a crucial step in protecting the capital city from pollution and to strengthen environmental balance.

(With inputs from HT correspondent)