Air quality improved during India’s lockdown, study finds – ScienceDaily
Research conducted by scientists from the University of Southampton (UK) and Central University of Jharkhand (India) and showed that the first COVID-19 lockdown in India led to an improvement in the quality of the air and a reduction in ground surface temperature in major urban areas across the country.
The study found that the travel and work restrictions imposed at the start of the pandemic resulted in a significant improvement in the environment, due to a sharp reduction in industrial activities and a significant decrease in the use of land and air transport.
The international team used data from a range of Earth observation sensors, including those from the European Space Agency’s Sentinel-5p and NASA’s MODIS sensors, to measure changes in surface temperature and air pollutants and aerosols. They focused on six major urban areas: Delhi, Mumbai, Kolkata, Chennai, Bangalore and Hyderabad – comparing data from the lockdown from March to May 2020 with the pre-pandemic years.
Their findings, published in the journal Environmental research, provide a strong evidence base for potential environmental benefits through scaling up policies.
Researchers found a significant reduction in nitrogen dioxide (NO2), a greenhouse gas emitted by the combustion of fossil fuels, which equates to an average decrease of 12% across India and 31.5% % in the six cities. There was a 40 percent reduction from the national capital, New Delhi. In India alone, around 16,000 premature deaths occur each year from exposure to poor air quality.
The study also found that land surface temperature (LST) in major Indian cities had dropped significantly, unlike the previous five-year average (2015-2019), with daytime temperatures up to 1 ° C cooler. and those at night up to 2 ° C. cooler.
Co-author Professor Jadu Dash, University of Southampton, commented: “The lockdown provided a natural experience for understanding the coupling between urbanization and the local microclimate. We clearly observed that the reduction in air pollutants (due to the reduction in anthropogenic activity during the lockdown) resulted in a decrease in local day and night temperature. This is an important discovery to integrate into sustainable urban development planning. “
Along with the surface temperature, atmospheric fluxes at the surface and at the top of the atmosphere have also decreased significantly in most parts of India. Reduced greenhouse gas concentration, higher atmospheric water vapor content, and weather conditions have played a complex role in reducing the temperature of the ground and near the surface.
Commenting on the research, Dr Bikash Parida, of Jharkhand Central University said: “Aerosol optical depth (AOD) and AOD absorption showed a significant reduction which could be related to the reduction in emission sources. across India during the lockdown. The type of aerosol sources, such as organic carbon (OC), black carbon (BC), mineral dust and sea salt. In addition, in central India, the increase in DOA was attributed to the supply of dust aerosols transported from the western region of the Thar Desert. . “
Dr Gareth Roberts of the University of Southampton added: “Satellite instruments play a vital role in acquiring information about the Earth’s environment in a timely manner. This study illustrated the importance of Earth observation data for monitoring changes in air pollutants, which are important health risk and highlighting the impact of human activities on regional air quality.
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