Delhi's annual PM2.5 levels rose in 2024 for the second consecutive year, despite a 37 per cent drop in stubble burning in Punjab, Haryana and the national capital. The report by the Centre for Science and Environment (CSE) said Delhi's annual PM2.5 concentration increased to 104.7 microgrammes per cubic metre in 2024 -- a 3.4 per cent rise from the 2023 levels. This is also more than twice the national ambient air quality standard of 40 microgrammes per cubic metre. Delhi recorded two major smog episodes this winter: from November 13-20 (about eight days) and from December 16-20 (about four days).
According to the report, the 2024 average is still 9.6 per cent lower than the 2018 peak of 115.8 microgrammes per cubic metre, it is 3 per cent higher than the three-year average of 2021-2023, indicating a gradual reversal of earlier gains made between 2018 and 2022. The report highlighted that the total annual fire counts (on account of stubble burning) dropped by 37.5 per cent in 2024 in Delhi, Punjab, and Haryana. Punjab recorded a 75 per cent decline, and Haryana, a 37 per cent decline.
“In 2024, the city’s annual PM2.5 levels rose to 104.7 µg/m³, marking a 3.4 per cent increase compared to 2023 and standing at 2.6 times higher than the national annual standard of 40 µg/m³. While the 2024 average is still 9.6 per cent lower than the 2018 peak of 115.8 µg/m³, it is 3 per cent higher than the three-year average of 2021-2023, indicating a gradual reversal of earlier gains. Delhi’s city-wide winter PM2.5 average for the October-December 2024 stood at 178.3 µg/m³, a level consistent with the average since large-scale monitoring began in 2018-19. This season’s average was 0.2 per cent lower than the 2019 winter average, but 4.6 per cent higher than the three-year winter average (2021-2023), based on data from 37 monitoring stations across the city”.
“However, a troubling trend emerges in peak pollution levels. The citywide winter peak for 2024 soared to 732 µg/m³, marking a 26 per cent jump compared to last year’s peak of 580 µg/m³. The city-wide peak this year stood at 602 µg/m³, recorded on November 18, 2024. The worst station-level peak this season was 9 per cent lower than the highest ever recorded -- at 806 µg/m³ during the 2018 winter,” it added.
According to the report, in 2024, approximately 121 days met the National Ambient Air Quality Standards, a trend similar to 2019, when the second-worst annual average was recorded at 109.1 µg/m³. However, there has been a noticeable decline in the number of good air quality days, dropping from 152 days in 2023 to 121 this year. Annually, while the number of "good" air quality days increased slightly from 25 in 2023 to 29 in 2024, this improvement was overshadowed by a marginal rise in the combined numbers of overall "very poor" or worse category days including "severe" and "severe-plus" categories, which climbed from 107 in 2023 to 111 days this year.
During the winter months (October to December), there were five days of "satisfactory" air quality -- up from three days recorded in the previous two years; but there were no "good" air quality days. Meanwhile, the number of days categorised as "poor" and "very poor" remained unchanged at 57, reflecting no progress in air quality during this critical period.
“This winter, only eight out of 37 CAAQMS (stations) showed improvement in their seasonal averages compared to the last three years. The most notable improvements were observed at DTU and NSIT Dwarka, which recorded 26 per cent and 22 per cent lower seasonal averages, respectively, compared to the mean of the previous three winters. On the other hand, three stations -- North Campus, Okhla Phase 2 and Jahangirpuri -- showed no change in their seasonal averages”.
“CRRI Mathura Road (22 per cent), Aya Nagar (17 per cent), Ashok Vihar and Vivek Vihar (each 15 per cent) and Pusa IMD (14 per cent) were the top five stations that recorded an increase in seasonal PM2.5 levels compared to previous winters. The seasonal averages ranged from 97 µg/m³ at DTU to 226 µg/m³ at Wazirpur, with Anand Vihar emerging as the second most polluted location in the city, recording a seasonal average of 224 µg/m³, it said.
Anumita Roychowdhury, executive director, research and advocacy, CSE, said the rise in PM2.5 levels cannot be seen as an annual aberration due to meteorological factors and consistent rise indicates the impact of growing pollution in the region.
"Delhi seems to be losing its air quality gains from past action. Local and regional sources of pollution including vehicles, industries, open burning of waste, use of solid fuels, construction and dust sources have offset the gains -- undermining the longer-term progress over the past decade.
"Delhi cannot hide behind the smoke screen of farm fires anymore. Despite a 71.2 per cent drop in stubble fire incidents during the October-December 2024, the winter pollution has remained elevated, upsetting the annual trend," she said.
The city experienced 17 days of severe or worse air quality, alongside two extended smog episodes with average smog intensity of 371 microgrammes per cubic metre and 324 microgrammes per cubic metre, respectively.The average daily intensity of this smog stood at 371 microgrammes per cubic metre and 324 microgrammes per cubic metre, respectively. At least three continuous days of severe AQI is considered a smog episode.
