Updated: June 25, 2021 10:25:46 am
A new analysis by climate communications initiative, Climate Trends, shows that pollution levels remained above permissible limits in Lucknow and Delhi, while Mumbai’s PM 2.5 concentration only increased year on year during the months of March, April and May, between 2019 and 2021. Kolkata was the only city in the study that showed improvement in the air quality in these months from 2019 to 2021.
Researchers compared the Central Pollution Control Board air quality data for Delhi, Lucknow, Mumbai and Kolkata over the three months of March, April and May in 2019, when there was no lockdown, and 2020 and 2021, when there was lockdown in these cities.
The study revealed that except Mumbai, all cities showed a dip in the average PM 2.5 levels during the three months in 2020. Mumbai’s average concentration of PM 2.5 between March to May in 2019 was 21.6 ug/m3, which increased to 31.3 ug/m3 in 2020 and then to 40.3 ug/m3 in 2021. The safe limit for PM 2.5 (particulate matter measuring less than 2.5 microns) as prescribed by the CPCB is 40ug/m3, according to the report.
“Mumbai, a coastal city, has a mixed effect of local meteorology and prevalent conditions of large-scale motions including that of cyclones. While cyclones such as Tauktae act as a washout/cleaning effect on the atmosphere, slow wind conditions and favourable conditions of long transport of particulate matters from neighbouring states act as accumulation, suggesting marginal increase of the pollutants,” said professor S K Dhaka from Rajdhani College, Delhi University.
On the other hand, Delhi’s average PM 2.5 concentration for the three months dipped from 95.6 ug/m3 in 2019 to 69 ug/m3 in 2020 but was quickly back to 95 ug/m3 in 2021. Similarly, Kolkata’s PM 2.5 concentration changed from 41.8 ug/m3 in 2019 to 27.9 ug/m3 in 2020 and 37.3 ug/m3 in 2021.
While there was a complete lockdown in 2020, the 2021 lockdown saw high movement of people seeking healthcare facilities due to increased Covid-19 cases and the state elections in West Bengal.
Lucknow saw its PM 2.5 concentration in the three months decrease consistently from 2019 but it still remained above permissible limits. Its average PM 2.5 concentration in 2019 for the months of March, April and May was 103 ug/m3, which dipped to 92 ug/m3 in 2020 during lockdown and further to 79.6 ug/m3 in 2021.
Dr G C Kisku, chief scientist of Environmental Toxicology, CSIR-Indian Institute of Toxicology Research, said, “The partial/complete lockdowns during 2020 and 2021 lowered vehicular movement and subsequently led to reduced consumption of fossil fuel. Closure of industrial establishments during lockdown periods also added to it. But the levels are still relatively higher this year. The good thing is that there has been a decreasing trend in PM10 levels from 2017 onwards. However, this year, the observed levels of PM 2.5, PM 10, SO2, and NO2 at all locations were found to be relatively higher as compared with monitoring data of previous year.”
The CSIR also recently released a report on the assessment of ambient air quality of Lucknow which showed that the mean levels of PM10 (127.1 μg/m3) and PM2.5 (64.5 μg/m3) at all the monitoring locations of residential, commercial and industrial areas from April-May 2021 were higher than permissible limits.
“Lockdown related reduction in air pollution is neither consistent nor uniform. Thus, the contribution of anthropogenic activities do not totally explain the high pollution level. We should stay alert about the continuing health hazards of high pollutant levels, especially in metropolitan cities. This is not the right time to let our guard down,” said Dr Arun Sharma, president of the Society for Indoor Environment.
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