Delhi-NCR pollution worsens ahead of Diwali; PM2.5 exceeds 461

Delhi’s air quality remained in the ‘very poor’ category on Wednesday, with the city’s Air Quality Index (AQI) recorded at 379, according to the Central Pollution Control Board (CPCB). Punjabi Bagh reported the worst reading at 458, placing it in the ‘severe’ category.

The city’s AQI had also remained in the ‘very poor’ category on Tuesday, when it stood at 332.

The pollution level has risen despite authorities tightening measures three days ago, including restrictions on traffic and construction, to tackle smog in the national capital. New Delhi is part of a wider metropolis with a population of more than 30 million.

Air pollution in parts of the city was more than 30 times the World Health Organization’s recommended daily limit on Wednesday. Levels of PM2.5, cancer-causing particles small enough to enter the bloodstream, exceeded 461 micrograms per cubic metre in some areas, according to monitoring firm IQAir.

Eight Delhi monitoring stations record severe air quality as AQI hits 332

Pollution is expected to worsen ahead of Sunday’s Diwali celebrations, when firework displays add to the already toxic air. The Supreme Court allowed the limited use of so-called “green” firecrackers this month. These are designed to reduce emissions, but restrictions are routinely flouted, with explosions continuing across the city.

According to India’s environment ministry, vehicles account for 23 per cent of Delhi’s winter pollution, while biomass burning, including farm stubble fires, contributes 20 per cent. Industry, including coal-fired power plants, accounts for about nine per cent.

The largest share, 27 per cent, comes from secondary particles. These are formed when gases released by vehicles, industries, power plants and biomass burning react in the atmosphere.

The formation of these particles is also fuelled by the large quantities of fertiliser spread on fields around the capital, according to Jacob Koshy, author of a new book on pollution.

Ammonia released by fertilisers reacts with other pollutants to form secondary particulate matter.

“The sheer quantity of ammonia that is going into the atmosphere creates a base layer for other pollutants to react with,” said Koshy, science editor of The Hindu newspaper and author of “The Nitrogen Bomb”.

Delhi’s winter pollution drive targets vehicles and construction sites

A 2024 study published in The Lancet Planetary Health, a peer-reviewed research journal, estimated that 3.8 million deaths in India between 2009 and 2019 were linked to air pollution.

Meanwhile, the minimum temperature at Safdarjung, Delhi’s primary weather station, settled at 16.1 degrees celsius on Wednesday, 0.8 degrees above the seasonal average, according to the India Meteorological Department (IMD).

Palam recorded a minimum temperature of 16.9 degrees celsius, 0.7 degrees above normal. Lodhi Road settled at 16.1 degrees celsius, 3.1 degrees above normal, while the Ridge station recorded 16.4 degrees celsius, 0.7 degrees below normal.

Ayanagar recorded a minimum temperature of 16.6 degrees celsius, 0.4 degrees above the seasonal average.

No rainfall was recorded at any of the five weather stations during the 24-hour period ending at 8.30 am on Wednesday.

According to the CPCB, an AQI reading between zero and 50 is classified as good, 51 and 100 as satisfactory, 101 and 200 as moderate, 201 and 300 as poor, 301 and 400 as very poor, and 401 and 500 as severe.

(With inputs from agencies)