The lockdown prompted by the Covid-19 outbreak from March 25 to June 8 helped to significantly reduce air pollution levels in Delhi, Mumbai, Kolkata and Bangalore, according to an analysis of the CPCB Air Quality Index data from the 74-day duration.
The four cities achieved 95 per cent of the National Clean Air Programme (NCAP) target set by the Centre, as per the analysis carried out jointly by CarbonCopy and Respirer Living Sciences.
In an attempt to ensure better air quality in cities, the NCAP was notified in January 2019 to reduce particulate matter (breathable pollutants that can easily enter the lungs and cause ailments) by 20-30 per cent by 2024. Over the course of the year, 122 non-attainment cities were added to this list and air pollution action plans were developed and approved for 102 of them.
“The lockdown period helped us understand the effects of anthropogenic (human-generated) emissions to our environment. All four cities managed to better their 2024 NCAP target by around 30 per cent, with Kolkata bettering their target by over 50 per cent during the lockdown. This period is a marker for policymakers on how they can achieve what has been planned for in the coming four years, in a relatively shorter period,” said Ronak Sutaria, CEO Respirer Living Sciences.
The analysis showed that Mumbai’s PM 2.5 average during the lockdown was 20, while the average was 40 in 2017, 47 in 2018 and 36.1 in 2019. Mumbai had to achieve a target of 28 PM 2.5. Kolkata’s average PM 2.5 during the lockdown was 22 as opposed to 69.3 2017, 86.2 in 2018 and 57.7 in 2019. The city’s target was 48.5.
Delhi’s PM 2.5 average during the lockdown was 49. It was 101.3 in 2017, 121 in 2018 and 109.2 in 2019. Similarly, Bangalore’s PM 2.5 average during the lockdown was 23; it was 46.1 in 2017, 47.4 in 2018 and 36.7 in 2019.
Similar reductions have been found in PM 10 levels during the lockdown in the four cities. In Mumbai, the average PM 10 level last year was 82.72 as opposed to 59 during the lockdown while Kolkata’s was 108.62 in 2019 compared to 45 during the lockdown. Delhi’s was 216.6 in 2019 as opposed to 49 during the lockdown and Bangalore had an average PM 10 level of 77.52 in 2019 as opposed to just 14 during the lockdown.
Dr Sagnik Dey, Coordinator of Centre for Excellence for Research on Clean Air (CERCA) at IIT-Delhi, said the reason behind this drastic fall in pollution levels is that out of the eight primary polluting sources in India, four were completely absent during the lockdown — vehicular emissions, emissions from industry, construction and brick kilns.
“Besides this, since the demand for power was so low, power demand plummeted by 19.9 per cent due to decline in industrial activity, coal-fired thermal power plants were also functioning less. PM2.5 levels ranged between 20-49 µg/m3 across these four major Indian cities during the lockdown, which means that in the best case scenario, we cannot go below that. The WHO guideline for clean air level is 10 µg/m3.”
“We also found this impact of falling pollution does not exist in rural areas. The main source of pollution there are emissions from household activities, which not only continued, but are likely to have increased. Also, since relaxation had been given to agriculture, we found through satellite data that open burning of crops actually increased in central and southern India, possibly leading to an increase in pollution. To bring down the average counts of different pollutants, and meet national standards, what the national policy really needs to look at is how to control pollution in these regions, while focusing on polluting sectors in urban India,” said Dr Dey.