City air 30% better in lockdown than 2024 NCAP target

The air quality in the city was around 30% better during 74 days of lockdown than its 2024 target under the National Clean Air Programme (NCAP).

The air quality in the city was around 30% better during 74 days of lockdown than its 2024 target under the National Clean Air Programme (NCAP).

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Notified in January 2019, NCAP was proposed by the Centre in its attempt to reduce the concentration of particulate matters — PM2.5, PM10 (breathable pollutants that can easily enter the lungs and cause health ailments) — by 20-30% by 2024. Over the course of the year, 122 non-attainment cities were identified and air pollution action plans were developed and approved for 102 of them.

During the lockdown from March 25 to June 8 owing to the Covid-19 pandemic, researchers calculated that Mumbai witnessed a 29.5% decline in PM2.5 and 44.3% decline in PM10 levels compared to the NCAP 2024 target. While the NCAP target for PM2.5 level was 28 micrograms per cubic metre (μg/m3), Mumbai recorded an average of 19.7 μg/m3 during lockdown. The target for PM10 was 105.7 μg/m3, while the city recorded 58.5 μg/m3.

A similar analysis for Delhi showed a 31% decline than its NCAP target, 54% decline for Kolkata and 29% decline for Bengaluru than their respective NCAP 2024 targets for PM2.5 pollutant.

The analysis — NCAP vs Lockdowns: An Assessment for Four Indian Cities — developed by Mumbai-based air quality research group Respirer Living Sciences (RLS) and Delhi-based communications initiative Climate Trends was released on Friday. Data for all cities was sourced from air quality monitors setup by the Central Pollution Control Board (CPCB), which is recognised as official data used to track the progress of NCAP by the Centre.

An overall trend established by the study showed the unprecedented lockdown measures resulted in all four cities achieving 95% of their 2024 NCAP targets.

Researchers said their analysis revealed that achieving clean air targets was possible much earlier than 2024 if restrictions were imposed on human-induced pollution sources in a phase-wise manner.

“The lockdown period helped us understand the effects from anthropogenic (human-generated) emissions. This period is a marker for policy makers on how they can achieve what has been planned in the coming four years, in a relatively shorter period,” said Ronak Sutaria, chief executive officer, RLS.

SN Tripathi, NCAP apex committee member and professor of Indian Institute of Technology (IIT), Kanpur, said, “The lockdown air quality data is being carefully studied by us and it is providing crucial information on baseline or background levels. This would help us to consider revisiting existing air quality safe standards for the country.”

The annual safe standard for PM2.5 as per the World Health Organization (WHO) is 10 μg/m3 while the national standard is 40 μg/m3.

According to Sagnik Dey, a professor at IIT-Delhi, of the eight primary polluting sources in India, four sources — construction, industries, brick kilns and vehicles — were inactive during lockdown while household emissions, open burning, diesel generators and dust were active. “Background levels for PM2.5 concentration during lockdown range between 20 μg/m3 and 49 μg/m3 across Delhi, Mumbai, Bengaluru and Kolkata; which means that in the best case scenario we cannot go below that,” said Dey.

Meanwhile, the latest analysis also assessed PM2.5, PM10 levels in four cities across 2017, 2018 and 2019 to highlight the effectiveness of NCAP in bringing down air pollution over the years, taking 2017 levels as the base year. While PM levels fell short of NCAP targets for all four cities in 2019 compared to previous years, Kolkata witnessed a 24% improvement followed by Bengaluru at 19.8%, Mumbai at 16%, and Delhi at 6.4%.

“Lessons from the lockdown make it clear that city action plans need to be much more comprehensive in their strategy and approach to air pollution management,” said Aarti Khosla, director, Climate Trends.

Maharashtra Pollution Control Board (MPCB) chairman Sudhir Srivastava said that reduction in transport pollution and work from home policy during lockdown had built an avenue to implement Mumbai’s action plan target for ‘staggered work hours’ for areas such as BKC and Parel. “Baseline data (from the lockdown) for a densely-populated city like Mumbai will tremendously help in source apportionment, especially for anthropogenic ones. This also expedites the process for obtaining necessary pollutant reduction as per our action plan through a more refined and enhanced approach,” he said.