NEW DELHI: Analysis of air pollution in the past few winters has revealed that PM2.5 levels in 2020-2021 were worse than the previous year. While one study was done by RWA body United Residents Joint Action (URJA) along with strategic communications outfit Climate Trends, the other was done by Respirer Living Sciences.
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The data set analysed by Respirer Living Sciences, a startup working on low-cost sensor based real-time air quality monitoring networks, showed that while March to September 2020 witnessed an improvement in air quality amid the lockdown, the average PM2.5 level from October 2020 to February 2021 was 186 micrograms per cubic metre (µg/m3) compared with 160 µg/m3 in 2019-2020 in the same months.
The average annual trends showed an improvement in PM2.5 in 2020, but the average PM10 level increased to 190 µg/m3 in 2020-21 from 160 µg/m3 in 2019-20. PM2.5 pollutants are emitted from anthropogenic sources, which were curtailed due to the lockdown, while PM10 is generated from dust.
The second analysis conducted by Climate Trends, which took the levels at RK Puram monitoring station as a baseline to underscore the trends in the city, showed that PM2.5 levels September onwards ranged higher compared with the levels in the same months in 2019. The levels in Delhi were nine times higher than WHO standards as well as the national average.
Dr Palak Balyan, consultant, Climate Trends, said, “The usage of personal vehicles in the winter of 2020 was more compared with 2019 due to the post-Covid situation where people avoided using shared or public transportation. Another possible explanation might be that the controlling authorities of Punjab and Haryana were busier with Covid control protocol, so regulation of crop stubble burning could not be implemented strictly.”
Atul Goyal, URJA president and member of the Supreme Court committee on solid waste management, said, “The data proves that Delhi’s air pollution levels are the worst from October to February. It seems there was a slackness in monitoring efforts on the ground and local sources of pollution, which resulted in losing gains made during the lockdown.”
Prof SN Tripathi, head of civil engineering department at IIT Kanpur and NCAP steering committee member, said, “Organic speciation of PM2.5 identified three major regional air corridors — northeast, east and northwest — from which heavy metals and industrial pollutants mix with Delhi’s air. The key pollutants brought by them are combinations of chromium-nickel-manganese, copper-cadmium-lead, lead-tin-selenium and chlorine-barium-selenium.”