PM2.5 level improves in Delhi but still twice national average

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Delhi recorded an annual average PM2.5 concentration of 99.71 micrograms per cubic metre (µg/m³) in 2022, Central Pollution Control Board (CPCB) data from the Capital’s 40 continuous ambient air quality monitoring stations (CAAQMS), showed on Sunday. While this is an improvement from last year’s annual concentration of 107.78µg/m³ and comparable to 2020’s annual concentration of 99.01µg/m³, these levels are still 2.5 times India’s national annual PM2.5 standard of 40µg/m³. According to data available on the CPCB’s website, Delhi has been showing a declining trend in the annual PM2.5 level since 2017.

The average PM2.5 concentration in 2017 was 118.43µg/m³, which improved to 114.86µg/m³ in 2018. In 2019, the concentration was 109.18, which dipped to 99.01µg/m³ in 2020, the lowest in the last six years. However, that was primarily down to a clean first half of the year, owing to Covid-19 induced lockdowns.

Delhi, despite no lockdown this year, recorded an average almost comparable to 2020, which experts say is due to a relatively clean winter. In 2020, despite a clean first half of the year, Delhi recorded a polluted winter, with 15 “severe” air quality days in the year. 2022, in comparison, only recorded six “severe” air days – when the air quality index (AQI) reading was over 400.

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An AQI reading between zero and 50 is considered “good”, 51 and 100 “satisfactory”, 101 and 200 “moderate”, 201 and 300 “poor”, 301 and 400 “very poor”, and 401 and 500 “severe”.

“2020 was an anomaly in the long-term trend since a lockdown was in place for a couple of months and the average pollution levels till summer were extremely low, but in winter, when the lockdown was lifted, pollution levels went up again. This year (2022) has been much better, largely on the winter front, as we have not seen smog spells like in the past few years. Even then, the annual average is fairly high and while it is a positive that the long-term trend is showing a continuous drop in the average annual concentration, we are still nowhere near the annual standards and so, sustained efforts are required on all fronts,” Anumita Roychowdhury, executive director, research and advocacy at the Centre for Science and Environment (CSE), said.

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CPCB data showed none of the 40 CAAQMS in Delhi was able to meet the annual standard of 40µg/m³, with southwest Delhi’s Ayanagar emerging as the cleanest location, with an average PM2.5 concentration of 69.97µg/m³. This is followed by the relatively green Lodhi Road (72.11µg/m³) and Najafgarh (76.32µg/m³), another agricultural-based, open area in southwest Delhi. Meanwhile, the industrial area of Jahangirpuri emerged as the most polluted location in Delhi, recording an average PM2.5 concentration of 128.07µg/m³ – over three times the national safe limit.

Anand Vihar was the second most polluted location in Delhi (125.43µg/m³), and India Meteorological Department (IMD)’s Burari Crossing station in north Delhi was the third most polluted location, based on the annual average PM2.5 concentration (121.7µg/m³).

Aarti Khosla, director at the environmental organisation Climate Trends, said air pollution levels in Delhi may have marginally dipped over the past few years, but are still well above the national limit. “The national standards set by the CPCB are much more relaxed compared to World Health Organization’s stringent air quality guidelines. This shows that a lot more work is needed to bend the curve and there is no substitute for reducing pollutants at source. Our recent survey among Municipal Corporation of Delhi (MCD) employees showed that while they are aware of the air pollution problem, they don’t know much about their role in fighting it. Bridging this gap would be a crucial first step to ensure better implementation of existing policies. With the same government now governing the MCD and the state, Delhi can hope for better solutions and coordination for air quality management in the region,” she said.

Tanushree Ganguly, programme lead at the Council on Energy Environment and Water (CEEW) said that while Delhi did better than last year in the winter, there was higher than usual pollution in summer, due to the lack of rain. In March and April this year, Delhi only received 0.3mm of rainfall combined. Normally, Delhi receives 15.9mm in March and 12.2mm of rainfall in April.

“While winter months (November-December) in 2022 were relatively cleaner compared to 2021, summer months (March-June) in 2022 were more polluted compared to 2021. This is mainly due to the prolonged dry spells during the summer and the consequent dust re-suspension in the air. This year’s cleaner winter months were mainly due to favourable meteorological conditions such as higher wind speed and temperature and proactive implementation of anti-pollution measures. This year also witnessed a revamped Graded Response Action Plan (Grap) that considers control measures based on air quality forecasts. Further, this year observed one of the lowest farm fire seasons in neighbouring states in the last five years. All these factors helped Delhi,” she said.

According to experts, recent steps that will help Delhi’s fight against pollution include a ban on polluting fuels across the national capital region (NCR), which sees coal banned in the region from January 1, 2023. This ban was put in place by the Commission for Air Quality Management in June last year, allowing only fuels in the ‘approved fuels’ list to be used in the region. The fuels not featured in the list of approved fuels include coal, light diesel oil (LDO) and Naptha — a liquid hydrocarbon mixture.

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