COVID-19 lockdown in 2020 improved air quality in India: Study

According to a study, the first lockdown implemented in India last year in response to the COVID-19 outbreak resulted in improved air quality and a reduction in land surface temperature in the country's largest cities. The findings, which were published in the journal Environmental Research, provide solid support for larger-scale policy implementation's potential environmental advantages. 

The study found that early in the pandemic, travel and work restrictions resulted in a significant improvement in the environment, owing to a sharp reduction in industrial operations and a considerable drop in the use of land and air transportation. To evaluate changes in surface temperature, air pollutants, and aerosols, the researchers analyzed data from a variety of Earth observation sensors, including those from the European Space Agency's Sentinel-5p and NASA's MODIS sensors.

Air quality improved in India during lockdown

They compared data from the lockdown in March to May last year with pre-pandemic years in six major cities including Delhi, Mumbai, Kolkata, Chennai, Bangalore, and Hyderabad. The study found a considerable reduction in nitrogen dioxide (NO2), a greenhouse gas released from the combustion of fossil fuels, equivalent to a 12% drop across India and a 31.5% reduction across the six cities.

As per the experts, there was a 40% decline in comparison to the national capital. According to them, poor air quality causes roughly 16,000 early deaths every year in India alone. In comparison to the preceding five-year average (2015-2019), the land surface temperature across major cities in India has significantly decreased, with day temperatures up to 1 degree Celsius colder and night temperatures up to 2 degrees Celsius lower.

Study co-author Jadu Dash, Professor at the University of Southampton in the UK stated, "The lockdown provided a natural experiment to understand the coupling between urbanization and local microclimate. e clearly observed that reduction in atmospheric pollutants resulted in a decrease in a local day and night-time temperature. This is an important finding to feed into the planning for sustainable urban development."

Environmental Research shows improved AQI

The study discovered that, along with the decrease in surface temperature, air fluxes at the surface and at the top of the atmosphere decreased dramatically over large areas of India. The drop of land and near-surface temperatures were influenced by a combination of factors including lower greenhouse gas concentrations, increased atmospheric water vapour content, and meteorological circumstances. The amount of direct sunlight that is blocked from reaching the ground by aerosol particles is measured by AOD.

Bikash Parida, from the Central University of Jharkhand, explained, "Aerosol optical depth (AOD) and absorption AOD showed a significant reduction which could be connected with the reduction in the emission sources across India during the lockdown. The aerosol type sources, such as organic carbon (OC), black carbon (BC), mineral dust, and sea salt also reduced significantly. Moreover, in central India, increases in AOD were attributed to the supply of dust aerosols transported from the western Thar desert region."

(with inputs from PTI)

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