Annual PM2.5 levels rose in 2024 for the second consecutive year, despite a drop in stubble burning

“This is not an annual aberration due to meteorological factors. Consistent rise indicates the impact of growing pollution. Delhi seems to be losing its air quality gains from past action”: AnumitaRoychowdhury, CSE 

  • Annual PM2.5 levels in 2024 shows a 3.4 per cent increase compared to 2023
  • Average PM2.5 levels in October-December 2024 was 4.6 per cent higher than three-year winter average (2021-2023). City-wide winter peak was 26 per cent higher than last year’s peak
  • 5 per cent drop in 2024 in total annual fire counts in Delhi, Punjab and Haryana. Punjab recorded 75 per cent decline; Haryana 37 per cent
  • Need urgent strategy to cut emissions from vehicles, industry, open fires, solid fuels in households, construction and dust sources, says CSE assessment
  • Scale and speed of action has to gather momentum to protect the gains from past action and accelerate progress to meet the clean air benchmark  

Find the complete CSE assessment report click here

New Delhi, January 6, 2025: As a new year begins, Centre for Science and Environment (CSE) has released an assessment of annual trends in levels of particulate matter 2.5 (PM2.5) in the air of Delhi in 2024 – and the findings are dark. The assessment shows “persistent and consistent rise for a second consecutive year since 2022”. 

The annual PM2.5 concentration has increased to 104.7 microgramme per cubic metre (µg/m³) in 2024 -- a 3.4 per cent rise from 2023 levels. This is also more than twice the national ambient air quality standard of 40 µg/m³. The PM2.5 levels have increased after consistent decline and stabilisation between 2018 and 2022, says the CSE assessment.   

AnumitaRoychowdhury, executive director, research and advocacy, CSE says: “This cannot be seen as an annual aberration due to meteorological factors. 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.” 

She adds: “Delhi cannot hide behind the smoke screen of farm fires any more. 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.” 

“Real-time data from Delhi’s monitoring stations for the winter period (October 1-December 31) reveals a troubling 26 per cent surge in peak pollution levels compared to the previous year during the early phase of winter. The city has experienced 17 days of severe or worse air quality, alongside two extended smog episodes with average smog intensity of 371 µg/m³ and 324 µg/m³, respectively. This has kept the average levels elevated,” says Sharanjeet Kaur,programme officerwith CSE’s Urban Lab. 

The methodology

This is an assessment of annual and seasonal trends in PM2.5 concentrations for the period October 1 to December 31 for the seven years from 2018 till 2024. This analysis is based on the real time data available from the current working air quality monitoring stations in Delhi-NCR. A huge volume of data points have been cleaned and data gaps have been addressed for this analysis,based on the USEPA method. It covers 37 continuous ambient air quality monitoring stations (CAAQMS) spread across Delhi. Fire count data has been sourced from NASA’s Fire Information for Resource Management System, specifically the Visible Infrared Imaging Radiometer Suite (VIIRS) product.

Keyhighlights

Delhi’s air quality worsens in 2024 -- annual PM2.5 levels shows an upward trend: Delhi’s annual PM2.5 levels have shown fluctuations over the years, with 2020 standing out as an exceptionally clean year due to the pandemic-induced lockdown that caused significant reductions in emissions. However, this improvement has not been sustained, and 2024 marks a concerning trend. 

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 winter air pollution stagnates, peak levels surge by 26per cent in 2024: 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. 

Two major smog episodes this winter: As is the global practice, at least three continuous days of severe AQI is considered a smog episode. During previous winters such episodes have been recorded lasting six-10 days. This winter,twomajor smog episodeswere recorded from November 13-20 – about eight days, and from December16-20 – about four days. The average daily intensity of this smog stood at 371 µg/m³ and 324 µg/m3,respectively. 

Trends in good and bad air days: 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.  

Variations in pollution level among city’s stations remain significant: 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 VivekVihar (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 AnandVihar emerging as the second most polluted location in the city, recording a seasonal average of 224 µg/m³. 

Farm stubble fires this winter about half of last winter:Farm stubble burning is widely regarded as a major contributor to elevated PM2.5 levels during the early winter months. However, this year a noticeable improvement has been reported, with the number of fire incidents in Punjab and Haryana declining significantly compared to previous years.

 Says Kaur: “VIIRS (Visible Infrared Imaging Radiometer Suite) data reveals a significant decline in fire counts across Punjab and Haryana during the critical October-December period in 2024 compared to 2023. The overall annual fire counts in three states (Delhi, Punjab and Haryana) have also shown a notable reduction.” 

In 2024, the total annual fire counts (Delhi, Punjab and Haryana) dropped from 63,721 in 2023 to 39,865, marking a decline of 37.5 per cent. The seasonal fire activity during October-December saw an even steeper reduction, from 37,276 in 2023 to 10,712 in 2024 -- a remarkable 71.2 per cent decrease. 

Punjab, a significant contributor to fire events, recorded a substantial 75 per cent decline in fire counts during the October-December period, dropping from 33,737 in 2023 to 8,449 in 2024. This improvement is reflected in the annual figures as well, which fell by 45.3 per cent, from 54,956 in 2023 to 30,081 in 2024. 

Haryana demonstrated a 37 per cent reduction in fire incidents during the October-December period, with fire counts decreasing from 3,479 in 2023 to 2,189 in 2024; but the annual fire counts increased slightly from 8,576 in 2023 to 9,532 in 2024.However, there have been observations from different authorities that the area affected by burning could have been large. 

The takeaways

CSE researchers point out that this 2024 round-up assessment of annual PM2.5 trends has come as a resounding warning about the heightened risk from rising air pollution levels and loss of air quality gains from past action. Delhi couldhave stabilisedannual PM2.5 levelssince 2018 (if the existing air quality monitors are considered) and could have even recorded a declining trend since 2013 (if the oldest five stations are considered) if it would have implemented the directives of the Supreme Court on energy transition in transport and industry sectors. 

Roychowdhury says that the action has to “move much beyond reactive emergency measures during winter. The fact that annual trends have risen for two consecutive years despite the decline in farm fire incidents during winter, shows much deeper systemic changes are required to cut the round-the-year emissions from a variety of sources in Delhi and the surrounding region”.  

It is now more important for Delhi to provide the details with respect to the scale of the problem ineach sector, gaps in action, targets to be achieved in each sector along with the strategies, and the resources to be mobilised to enable implementation with a strong compliance framework, says the CSE assessment.  

For more details, interviews etc, please contact Sukanya Nair of The CSE Media Resource Centre: sukanya.nair@cseindia.org, 8816818864

 

 

Tags: