Delhi’s PM2.5 lowest in 5 yrs but highest in NCR

NEW DELHI: Delhi logged its cleanest winter season in five years in 2022-23 with respect to PM2.5 particulates, an analysis by the Centre for Science and Environment (CSE) has shown. However, among all the cities in the National Capital Region (NCR), Delhi still had the highest concentration of PM2.5 particulates, the study adds.

“The city-wide winter average for Delhi stood at 160 micrograms per cubic metre (µg/m³) for the October-january period, which is the lowest level recorded since wide-scale monitoring started in 2018-19. The PM2.5 level, computed by averaging monitoring data from 36 continuous ambient air quality monitoring stations in the city, was 17% lower compared to the seasonal average of 2018-19 winter. Based on the subset of the 10 oldest stations in Delhi, there is an improvement of almost 20%,” the analysis said.

In comparison, Delhi’s PM2.5 levels were 171 µg/m³in 2021-22, 186 µg/m³ in 2020-21, 173 µg/m³ in 2019-20 and 193 µg/m³ in 2018-19, the study said. To be sure, the 2022-23 number is still considerably higher than the 24-hour national ambient air quality standard of 60 µg/m³, or the annual standard of 40 µg/m³ as prescribed by the Central Pollution Control Board.

The winter season is the most polluted time of the year, with farm fires raging in neighbouring states, and unfavourable weather conditions trapping pollutants close to the surface, including calm winds, low temperature and fog. Anumita Roychowdhury, executive director, research and advocacy at CSE said this winter, the conditions were not as harsh, with Delhi also being aided by emergency-based action.“there was also heavy and extended rain in the early phases of the season that prevented smog episodes from building up,” she said.

The analysis, released on Monday, also found that 12 out the 13 pollution hots pots had shown a marked improvement in PM2.5 levels compared to the average pollution levels recorded over the previous three seasons, thanks to a combination of favourable meteorology and forecast-based action, with the only outlier being RK Puram. Hotspots in north and east Delhi were the most polluted locations in the city. “Jahangirpuri was the most polluted neighbourhood with October-january average PM 2.5 level of 201 µg/m³, while Okhla-phase 2 was the least polluted, recording an average of 167 µg/m³,” the report said.

To be sure, PM2.5 is not the only criteria to measure air pollution, with Central Pollution Control Board’s Air Quality Index (AQI) including eight pollutants — PM2.5, PM10, ozone, sulphur dioxide, nitrogen dioxide, carbon monoxide, lead and ammonia. Experts consider PM2.5 to be the most dangerous, as prolonged exposure is linked with respiratory and heart diseases.

Across NCR, Noida was the least polluted among the major cities, recording an average of 124 µg/m³ this winter. Greater Noida recorded an average of 143 µg/m³, Faridabad and Gurugram 133 µg/ m³, and Ghaziabad 132 µg/m³. “This downward trend will have to be sustained with stronger action on vehicles, industry, waste burning, construction etc,” Roychowdhury said.