Bengaluru: Hacking coughs, smogs hindering visibility, schools stopping physical classes, construction being halted for some days, private vehicles not permitted to ply on many others – residents of Delhi witnessed all this and more due to hazardous levels of air pollution in 2024.
Now, a detailed analysis by the Delhi-based Centre for Science and Environment (CSE) released on Monday (January 6) shows that the annual concentration of fine particulate matter – a major air pollutant – increased by 3.4% in 2024 in Delhi when compared to 2023. And alarmingly, this has occurred despite a huge decrease (by 71.2%) in the counts of stubble fires during the winter of 2024. This clearly points to local and regional sources of pollution, including vehicular emissions, open burning of waste and dust from construction and other sectors, causing air pollution in the national capital, the report said.
Increase in levels of fine particulate matter
Analysts at CSE assessed annual and seasonal trends in the concentration of fine particulate matter (or PM2.5, particulate matter that is less than 2.5 microns in diameter and is a major air pollutant that is released from sources including construction dust, emissions from thermal power plants and vehicles) between October 1 and December 31 across seven years – 2018, 2019, 2020, 2021, 2022, 2023, and 2024 – using real time data from 37 air quality monitoring stations in Delhi-NCR.
The team found that in 2024, the annual concentration of PM2.5 increased to 104.7 µg/m3, up by 3.4% from 2023. This is more than twice the ideal levels prescribed by national standards. As per India’s National Ambient Air Quality Standards (NAAQS) of 2019, the concentration of PM2.5 should ideally be no more than 40 µg/m3 annually.
Delhi’s PM2.5 levels, therefore, have increased after a decline and stabilisation that the city witnessed between 2018 and 2022. The spike in the levels of PM2.5 in Delhi “cannot be seen as an annual aberration due to meteorological factors,” said Anumita Roychowdhury, executive director, research and advocacy, CSE, in a press release on January 6.
“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,” Roychowdhury said.
The team also analysed fire count data sourced from NASA’s Fire Information for Resource Management System. This revealed that farm fires – farmers setting fire to stubble after harvests in neighbouring areas including Punjab and Haryana – had declined drastically in 2024.
In 2024, the total annual fire counts across Delhi, Punjab and Haryana numbered just 39,865, dropping from 63,721 in 2023 – a decline of 37.5%. Seasonal fires decreased in 2024 by an even larger margin. Between October and December, stubble fires dropped from 37,276 in 2023 to 10,712 in 2024 – a staggering 71.2% decrease. This means that the Union and Delhi governments cannot ascribe the rising pollution levels in the national capital to stubble burning anymore.
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“Delhi cannot hide behind the smoke screen of farm fires any more,” Roychowdhury said. “Despite a 71.2% drop in stubble fire incidents during October-December 2024, the winter pollution has remained elevated, upsetting the annual trend.”
The government’s stand: 2024, a golden year for Delhi’s air
Government statements, such as those made through press releases, however, paint a completely different picture.
Just six days ago, a press release by the Ministry of Environment, Forest and Climate Change (MoEFCC) said that air quality in Delhi has improved, as is “evident” from the “record” 209 days during the year when Delhi’s Air Quality Index remained below 200. This, as per India’s categories of air quality is ‘good’ to ‘moderate’.
But first, some background to put this in perspective. What’s important to note here is that India has rather lax standards on what counts as acceptable PM2.5 levels: good (0-30 µg/m3 for a 24-hour period), satisfactory (31-60 µg/m3), moderate (61-90 µg/m3), poor (91-120 µg/m3), very poor (121-250 µg/m3) and severe (more than 250 µg/m3).
As per 2019 NAAQS, the concentration of PM2.5 should ideally be no more than 60 µg/m3 for a 24-hour period (and 40 µg/m3 annually). Contrast this to the World Health Organisation’s (WHO’s) standard that is four times more stringent: it recommends that levels of PM2.5 should be no more than 15 µg/m3 for a 24-hour period (and 5 µg/m3 annually).
Now, back to the recent press release by the MoEFCC:
“Continual, concerted and persistent efforts of all the stakeholders round the year also in 2024 have further helped to improve the general air quality in Delhi as is evident from a record 209 days during 2024 with the AQI falling below 200 i.e. in “good – moderate” air quality category,” the press note read.
The note focused on how 2024 was seemingly a golden year for air quality in the national capital. The months of February and December witnessed the “best ever average AQI” in the city since 2018; as did the August of 2024 (except for 2020, during COVID-19 when a lot of restrictions had ensured that pollution levels were low).
The city witnessed the “best ever average AQI” for the months of February and December during 2024, since 2018; and the month of August, 2024, also recorded this best ever average AQI since 2018 (barring the year of 2020). The months of March and April in 2024 also witnessed the “second best daily average AQI” since 2018 (again, barring the same months in the year 2020).
“Based on gradation of the average AQI, the year 2024 witnessed the best ever “good to moderate” and the least ever “poor to severe” AQI days (barring COVID affected 2020),” the press note said.
The press note blamed low wind speed conditions, as well as “exceptionally prolonged dry spells” and high-speed winds that carried fine dust and particulate matter from adjoining areas, for the “poor” AQI in the months of January, April, May and June. But despite this, the average AQI for 2024 was the second-best since 2018, barring the year 2020, the note said.
What the note misses entirely, however, is the fact that even several of the government’s air quality monitors maxed out at an AQI of 500 in the month of November last year. So much so that the Central Pollution Control Board had to admit in its daily AQI bulletin on November 18 that Delhi’s AQI clocked 494 as of 4 pm on the day, with fine particulate matter being the prominent pollutant. Meanwhile, other private air quality monitoring equipment including readings by the Swiss real-time air monitoring agency IQAIR clocked AQI figures of 1113 and higher on the same day, which counts as “hazardous” air quality levels as per the US AQI levels (these, however, are calculated differently).
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The latest CSE analysis published on January 6 confirms this. Between October 1 and December 31 last year, real time data from monitoring stations in Delhi revealed a staggering 26% increase in peak pollution levels (from 580 µg/m3 in 2023 to 732 µg/m3 in 2024) when compared to the same time period in 2023, the report said. Day-wise, the city-wide peak in 2024 occurred on November 18, when pollution levels rose to 602 µg/m3.
The CSE report also noted that between October and December this year, the city witnessed 17 days of severe or worse air quality which also included two extended smog incidents (defined as three consecutive days of “severe” air quality) between November 13-20 and December 16-20. This further kept the average pollution levels high in the city during the winter.
“The fact, that the 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 explosive traffic, industry, open burning of waste and biomass, construction activities, use of solid fuels for cooking, and dust sources in Delhi and the surrounding region,” the report noted.
