Delhi, Mumbai, Bengaluru and Kolkata attain 95% of clean air targets during lockdown


The clampdown on all non-essential activities due to the COVID-19 pandemic has led to a significant decline in air pollution levels in major cities across India, including Mumbai. Archived image by Bishnu Sarangi from Pixabay

The clampdown on all non-essential activities due to the COVID-19 pandemic has led to a significant decline in air pollution levels in major cities across India.

Researchers from Respirer Living Sciences and Carbon Copy have analysed average air quality during all four lockdown phases in India as well as concentrations of PM2.5, PM10, nitrogen dioxide (NO2), carbon monoxide (CO), ozone (O3), and Benzene during individual phases for Delhi, Mumbai, Kolkata and Bengaluru, as part of their on-going National Clean Air Programme (NCAP) Tracker project to monitor the implementation of the NCAP.

Four cities witness clean air

From March 25 to June 8, 2020, four different phases of the lockdown showed a variety of restrictions being imposed on human-induced sources of air pollution, that not only led to clean air but allowed researchers to carry out studies tracking base levels at mega cities in India affected by poor air quality.

The trends established that the unprecedented lockdown measures resulted in these four cities achieving 95% of their 2024 NCAP targets in a short span of 74 days.

The entire data has been sourced from air quality monitors set up by the state pollution control boards under the aegis of the Central Pollution Control Board and recognised as official data, which is being used by the NCAP. 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.

The lockdown period helped the researchers understand the effects of anthropogenic (human-generated) emissions on the environment. 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

“The four cities managed to better their 2024 NCAP target by around 30%, with Kolkata bettering their target by over 50% during this lockdown.”

Ronak Sutaria, Chief Executive Officer (CEO), Respirer Living Sciences

During a webinar hosted by Delhi-based communications initiative, Climate Trends, Dr Sagnik Dey from Indian Institute of Technology, Delhi explained that out of the eight primary polluting sources in India, four were completely closed during the lockdown period — namely construction and industrial activity, brick kilns and vehicles.

According to Carbon Copy that analyses India’s Power Sector, between March 25 and June 8, power demand plummeted by 19.9% year-on-year due to a 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 total shut down was an opportunity to understand the background pollution levels in India, which will be present even in the best-case scenario. “The PM2.5 levels ranged between 20-49 μg/m3 across the four cities during the lockdown, which indicates that the levels cannot go below that. The WHO guideline for clean air level is 10 μg/m3,” explained Dr Sagnik Dey, Coordinator of Centre for Excellence for Research on Clean Air (CERCA) at IIT-D.

Challenges in assessing overall pollution status

The tracker also analysed PM2.5 and PM10 levels in these four cities across 2017, 2018 and 2019 to demonstrate the effectiveness of the NCAP in bringing down pollution, taking levels in 2017 as the base year.

While Kolkata witnessed an approximate 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.

Ronak Sutaria explains that comparing the yearly data has nuances and the results are however not so simplistic. While the 2019 data was available from the online monitoring network as part of the Continuous Ambient Air Quality Monitoring (CAAQMS) programme, data for 2017 and 2018 comes from the manual monitors under the National Air Quality Monitoring Programme (NAMP).

“Comparing the data across these years gets challenging. Also, the 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,” Ronak said.

Need for green recovery model

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

The drastic reduction in pollutants across cities strengthens the fundamental need for managing air quality as a regional issue, across the same air shed, such that gains of clearer skies can happen along with growth and economic activity.

For Delhi, which saw an average decline of 30% in PM2.5 values in the lockdown, the solutions are complex. A recent real-time source apportionment study by IITs Kanpur and Delhi establishes that the national capital is exposed to 35 heavy metal pollutants from 3 regional air corridors from the North-West, North-East and East.

“Bringing all economic activity to a halt brought about gains in air quality which have otherwise been envisaged as part of the next five years, to be achieved through the NCAP. 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,” stated Aarti Khosla, Director, Climate Trends.

[This article presents a press release from Delhi-based communications initiative, Climate Trends, and has been published with minimal edits]

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