KOLKATA: In the March-May period last year as well as this year, the air pollution level in Kolkata recorded the sharpest dip against 2019 among the four most-polluted cities — Delhi, Kolkata, Lucknow and Mumbai.
Researchers compared the Central Pollution Control Board (CPCB) air quality data of these four cities over the three months in 2019 when there was no lockdown and 2020 when there was complete lockdown as well as 2021 when there were restrictions in these cities.
Track the pollution level in your cityAn analysis by climate communications initiative ClimateTrends shows pollution levels remained above permissible limits in the cities of Lucknow and Delhi while Mumbai’s PM 2.5 concentration only increased year on year during the months of March, April and May from 2019 to 2021.
Also part of the study was Kolkata, which was the only city to show the maximum improvement in air quality.
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 PM2.5 between March to May in 2019 was 21.6µg/m3, which increased to 31.3µg/m3 in 2020 and 40.3µg/m3 this year.
The safe limit for PM2.5 (particulate matter measuring less than 2.5 microns) as prescribed by the CPCB is 40µg/m3.
Kolkata’s PM2.5 concentration swayed from 41.8µg/m3 in 2019 to 27.9µg/m3 in 2020 and 37.3µg/m3 in 2021.
While there was a complete lockdown in 2020, the restrictions this year saw high movement of people seeking health-care facilities due to incre-ased Covid-19 cases and the state elections.
“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.
Thus, we should stay alert about the continuing health hazards of high pollutant levels, especially in metropolitan cities.
And this is not the right time to let the guards down,” said Society for Indoor Environment president Arun Sharma.
Any relief from lockdown-resultant pollution levels cannot be rejoiced, felt experts.
Since the unprecedented nationwide lockdown in 2020, experts have claimed that it gave them a first-ever opportunity to understand background pollution levels in India when the majority of the polluting sources were not at play.
In 2020, out of the eight primary pollutant sources in India, four were completely closed during the lockdown period — construction and industrial activity, brick kilns and vehicles.
Meanwhile, sources like household emissions, open burning, diesel generators and dust remained operational along with coal-fired thermal power plants at reduced capacity.
CSIR-Indian Institute of Toxicology Research chief scientist (environmental toxicology) G C Kisku said: “The complete lockdown during 2020 and partial one in 2021 reduced vehicular movement and led to reduced consumption of fossil fuels.
Closure of industrial establishments during lockdown periods also added to it.
But the levels are still relatively higher this year.”