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Lockdown effect on air quality shows areas for action, sheds light on background pollution in India

New Delhi, July 3, 2020: The lockdown enforced to control the COVID 19 pandemic in India led to a significant decline in air pollution levels for major cities across India. Researchers from Respirer Living Sciences and Carbon Copy analysed average air quality during the four national lockdown phases as well as during local lockdowns initiated by metros Delhi, Mumbai, Kolkata and Bengaluru. Concentrations of PM2.5, PM10, nitrogen dioxide (NO2), carbon monoxide (CO), ozone (O3), and Benzene were tracked as part of the on-going NCAP Tracker project to monitor the implementation of the National Clean Air Programme (NCAP).

Restrictions on economic activity between March 25 and June 08 saw pollution levels plummet across the country and offered researchers an opportunity to track baseline pollution levels in major Indian cities- a bit of crucial information that had so far remained elusive. The trends established that the unprecedented lockdown measures resulted in these 4 cities achieving 95% of their 2024 NCAP targets in a short span of 74 days.

“The lockdown period helped us understand the effects from anthropogenic (human-generated) emissions to our environment. All four cities analysed managed to better their 2024 NCAP target by around 30%, with Kolkata bettering their target by over 50% during this lockdown. This period is a marker for policy makers 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 data used for the analysis was obtained from air quality monitoring stations setup by the State Pollution Control Boards. In the Centre’s attempt for cities to have better air quality, the NCAP was notified in January 2019 seeking to reduce particulate matter (breathable pollutants that can easily enter the lungs and cause ailments) by 20-30% 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.

Experts claim that the lockdown gave them an opportunity to understand background pollution levels across India as four of the eight major sources of air pollution in India stalled due to the lockdown—namely construction, brick kilns, vehicles and industrial activity. “PM2.5 levels range between 20-49 μg/m3 across these 4 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 which maybe impossible for us to attain given our background pollution levels, and might need to be rethought for geographies like India” said Sagnik Dey, coordinator at the Centre for Excellence for Research on Clean Air (CERCA) in IIT-Delhi, during an April, 2020 webinar on the impacts of the lockdown on air quality.

Between March 25 and June 8, power demand plummeted by 19.9% y-o-y due to decline in industrial activity. Coal fired thermal power plants are
one of the key sources of air pollution in India. Meanwhile, sources like household emissions, open burning, diesel generators and dust were operational during the lockdown period.

The above graph is a representation of how air quality (PM2.5 and PM10) changed during the lockdown while comparing the prescribed or promised concentration for PM2.5 and PM10 reduction as sought by NCAP.

The tracker also analysed PM2.5 and PM10 levels in the 4 major cities across 2017, 2018 and 2019 to demonstrate NCAP’s effectiveness in bringing down pollution, taking 2017 as the base year. While Kolkata witnessed approximately a 24% improvement in PM levels in 2019 in comparison to 2018, Mumbai averaged at 16%, Bengaluru at 19.8% and Delhi at 6.4%. But this improvement falls short of the NCAP targets. Delhi’s PM2.5 annual average level in 2019 was 109.2 µg/m3, the PM2.5 target for Delhi in 2019 as deemed by NCAP was 70.9 µg/m3. This means that Delhi needed to achieve a reduction of 35% in 2019 to achieve its NCAP target. Similarly, Mumbai’s PM.25 annual average in 2019 was 36.1 µg/m3, while the target for the city was 28 µg/m3, therefore Mumbai also fell short by 22.4% in meeting its NCAP targets in 2019. Meanwhile, Kolkata fell short by 16% and Bengaluru by 12.1% in their respective NCAP targets in 2019.

The yearly data though has nuances that complicate inferences. While cross comparing sources between different monitoring networks, as was required for this analysis, can be challenging, there is also the issue of missing data from the manual monitors installed under the National Air Quality Monitoring Programme (NAMP), especially during crucial winter months, explains Ronak Sutaria. “Manual monitoring data for 2019 is not yet available for the key winter months, making it further difficult to establish conclusive findings if there’s an actual improvement in pollution levels in 2019.”

The drastic drop in pollution levels during the lockdown teaches lessons in India’s air pollution management which need to be incorporated in achieving the country’s clean air targets. Clearly levels can be brought down dramatically if India focuses its energy towards a green recovery model which is less emission-intensive.

This new analysis of air quality during the lockdown comes quick on the heels of a real-time source apportionment study for Delhi’s air pollution conducted by researchers from IITs in Kanpur and Delhi. The source apportionment study found at least 35 heavy metal pollutants brought through three prominent air corridors to which the national capital is exposed.

The complete analyses can be accessed here.

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