Unlike other major cities, Kolkata showed improvement in air quality from March to May from 2019 to 2021
If anything good happened in the country which has been hit by Kovid since last year, it was some clearing of the sky and a feeling of less pollution levels.
This is because an analysis by Climate Trends, an organization focused on climate communication, shows that air pollution levels in the years 2020 and 2021 remained above permissible limits despite lockdowns in important cities such as Lucknow and Delhi. Mumbai’s PM 2.5 concentration has increased year-on-year during the months of March, April and May. Kolkata was also a part of the study and it was the only city to show an improvement in air quality in these months from 2019 to 2021.
The researchers compared Central Pollution Control Board (CPCB) air quality data for Delhi, Lucknow, Mumbai and Kolkata in the three months of March, April and May 2019 with data for the years 2020 and 2021. The study showed that except Mumbai, all cities saw a decline in average PM 2.5 levels during these three months in 2020.
The average concentration of PM 2.5 in Mumbai between March and May in 2019 was 21.6 ug/m3 which increased to 31.3 ug/m3 in 2020 and then increased to 40.3 ug/m3. The safe limit for PM 2.5 (particulate matter measuring less than 2.5 microns) prescribed by the CPCB is 40 µg/m3. “Mumbai being a coastal city suffers a mixed effect of local meteorology and prevailing wind speed conditions including cyclones on a large scale. Whereas cyclones like Taukte act as a washout/cleaning effect on the atmosphere; Slow wind conditions, favorable conditions for long transport of particulates from neighboring states, act as accumulations indicating a slight increase of pollutants,” Professor S.K. Dhaka, Rajdhani College, University of Delhi, said.
On the other hand, Delhi’s average PM 2.5 concentration for three months declined from 95.6 ug/m3 in 2019 to 69 ug/m3 in 2020, but it soon returned to 95 ug/m3 in 2021. Similarly, Kolkata’s PM 2.5 concentration swings 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, West Bengal during the 2021 lockdown saw high movement of people due to state elections and demand for health facilities due to increase in cases of COVID-19.
Lucknow, the capital of Uttar Pradesh, saw a decrease in the concentration of PM 2.5 for three consecutive months from 2019, but it remained above the permissible limit. The average PM 2.5 concentration here was 103 ug/m3 in 2019 for the months of March, April and May, which further reduced to 92 ug/m3 in 2020 and further down to 79.6 ug/m3 in 2021.
Chief Scientist, Environmental Toxicology (Toxicology), CSIR-Indian Institute of Toxicology Research, Dr. G.C. Kisku, said, “The partial/complete lockdown during 2020 and 2021 reduced vehicular movement and subsequently reduced the consumption of fossil fuels. The closure of industrial establishments during the lockdown period also helped. But The levels are still relatively high this year. The good news is that PM 10 levels have come down since 2017, however, this year compared to last year’s monitoring data, PM 2.5, PM 10, The observed levels of SO2 and NO2 were found to be relatively high.” Dr Kisku has also recently released a report on the assessment of the air quality of Lucknow.
Experts believe that there cannot be any sigh of relief from the level of pollution as a result of the lockdown. “The lockdown-related reduction in air pollution is neither consistent nor uniform. Thus the contribution of anthropogenic activities does not fully explain the high pollution level. We must be especially vigilant about the continuing health hazards of high pollutant levels, especially in metropolitan cities. And this is not the right time to reduce vigilance,” said Dr. Arun Sharma, President, Society for Indoor Environment.
Since the unprecedented nationwide lockdown in 2020, experts have claimed that it has given them a unique opportunity to understand the level of pollution in India, when most sources of pollution remained non-existent. In 2020, four of the eight primary pollution sources in India were completely shut down during the lockdown period – namely construction and industrial activity, brick kilns and vehicles. Meanwhile, sources such as domestic emissions, open burning, diesel generators and dust remained operational with coal-fired thermal power plants at low capacity. The 2021 lockdown was not that complete, although it allowed a comparative analysis between the two years.
Professor S.K. Dhaka, Rajdhani College, University of Delhi, also said, “The lockdown has provided an opportunity to conduct background pollution checks in an environment when everything was shut down in 2020; The atmosphere was quite clear but we could not reach the level of 40 ug/m3 prescribed by the CPCB. We need to redefine the natural conditions in India for which the concentration of particulate matter still exceeds 50-60 ug/m3 in the clean environment of North India.”