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Farm fires caused just 4% of Delhi’s air pollution, vehicles main culprit, finds pre-Diwali analysis

Number of bad air days increased as compared to same period in 2023 & 2022, according to CSE. Local sources in Delhi & neighbouring areas responsible for this, it adds.

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New Delhi: A pre-Diwali analysis of Delhi’s air pollution has attributed the smoggy skies and deteriorating air quality to local sources in the national capital and neighbouring regions, particularly vehicular emissions. Stubble burning had an overall contribution of less than 5 percent to Delhi’s current air pollution, the report from the Centre for Science and Environment (CSE) said.

The CSE report, published 30 October, analysed the PM2.5 (fine particulate matter) concentration levels in Delhi from 15 September to 28 October and the contribution of different sources of pollution to the spike in air quality index (AQI).

Over the 45 days, Delhi had 16 days of ‘poor’ and ‘very poor’ AQI (5 & 11, respectively). This marked an increase from the 13 total days of ‘poor’ and ‘very poor’ AQI recorded in 2022 and 2023. This, however, is also seen as the ‘pre-Diwali’ period before pollution worsens in Delhi because of the bursting of firecrackers and increased stubble burning.

According to the report, vehicular pollution was among the main culprits in Delhi’s air quality deterioration. It led to a sharp increase in PM2.5 levels, which crossed 100 micrograms per metre cube (µg/m³) on 14 October, reaching a peak of 214 µg/m³ on 23 October—above the 2021 World Health Organisation annual guideline level of 5µg/m3.

However, analysis of the data from the Decision Support System (DSS) for Air Quality Management by Indian Institute of Tropical Meteorology, Pune found that even on the worst day, the contribution of stubble burning to pollution was only 16 percent.

On average though, farm fires and stubble burning made up only 4.44 percent of the total PM2.5 concentration levels, while local sources in Delhi and neighbouring areas made up 33 percent. Within local Delhi sources, transport emissions accounted for a whopping 52 percent of the pollution.

“It is stunning to see the contribution of vehicles among the local sources of Delhi, to Delhi’s air quality – it is more than half. With the overall number of farm fire count declining, the city cannot hide behind its smokescreen anymore,” Anumita Roychowdhary, executive director of research and advocacy at the CSE, said in a press release.


Also Read: Air pollution surpasses smoking, becomes 2nd-highest risk factor for strokes globally—Lancet study


Pollution from outside a major contributor, too 

The CSE report specifically focuses on particulate matter pollution which is harmful to human health. It is caused by a higher concentration of particulate matter that is 2.5 microns or less in diameter (PM2.5)—30 times smaller than the diameter of human hair.

A deeper analysis of pre-Diwali congestion on busy roads, such as GT Karnal Road, Baba Banda Singh Bahadur Marg, Outer Ring Road, and Bahadur Shah Zafar Marg, during this period, revealed that the average speed on Delhi’s main roads reduces by almost 40 percent. This can be as high as 57 percent on weekday evenings. Idling vehicles produce higher emissions making congestion a huge contributor to air pollution.

“An added challenge has been the escalation in congestion index of major roads across Delhi, which has further aggravated the pollution exposure. Vehicles caught in congestion and idling emit several times more than their normal on-road emissions,” said Shubham Srivastava, programme officer for CSE’s clean air programme.

In this period, other sources of local pollution in Delhi, such as residential burning at 13 percent, industry at 11 percent, and construction at 7 percent, also contributed to the higher PM2.5 levels.

Also, a major source (almost 30 percent) came from pollution sources in areas outside Delhi and the National Capital Region (NCR), including Haryana, Uttar Pradesh, and Rajasthan. But, as the report specified, this 30 percent did not include pollution from farm fires.

The report concluded that Delhi cannot “hide behind” the excuse of farm fires and needs to adopt a broader approach to target local pollution sources like vehicles, industries, construction and especially the burning of solid fuels. It also recommended a “region-based and airshed mitigation strategy” given the contribution of neighbouring areas to the pollution.

“This demands very stringent advanced action at scale and with speed to minimize the local pollution in Delhi and in the surrounding region,” the CSE said.

(Edited by Sanya Mathur)


Also Read: Air pollution killed 16 lakh Indians in 2021, says Lancet report. India second-highest PM2.5 emitter


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