Air pollution over north, west India increased during lockdown, in contrast to other parts of the country

Vijay Mohan
Tribune News Service
Chandigarh, December 27

Satellite observations have revealed that reduction in economic activities during the pandemic-related lockdown notwithstanding, there was an increase in air pollution levels over north India and central-western India. This is in contrast to the general trend in other parts of the country.

Based on analysis of satellite data, scientists have suggested that certain regions in north India and central-western India are prone to higher air pollution exposure and hence are exposed to greater risk of respiratory problems. This could have aggravated respiratory health risks around those regions during the pandemic.

In 2020, a complete nationwide lockdown was imposed to mitigate the spread of Covid-19. While this had enormously disrupted the economy, the single positive side effect was a short-term improvement in the air quality.

Scientists at the Aryabhatta Research Institute of Observational Sciences (ARIES), Nanital, used EUMETSAT and NASA satellite observations for the years 2018, 2019, and 2020 to investigate the influence of significant reduction in anthropogenic activities on the changes in the distribution of ozone, carbon monoxide and nitrogen dioxide during the lockdown period.

The study published recently in the Environmental Science and Pollution Research journal showed that ozone, carbon monoxide, and nitrogen dioxide showed an increase of about 15 per cent over central-western part of India. Carbon monoxide showed an increase of as high as 31 per cent at higher altitudes.

The long-range transport and downward transport from the stratosphere significantly increased ozone concentrations over north India during the lockdown. Remote regions like the Himalayas and coastal cities showed the bare minimum influence of lockdown in air quality, with a tendency to increase in air pollutants, the study observed.

According to ARIES scientists, ozone production and loss are constrained through the complex photochemistry involving its precursor gases. A decrease in precursor gases could also lead to enhancement of ozone, depending upon the chemical environment. Ozone concentrations are also altered by ambient meteorology and the downward transport of ozone-rich air from the stratosphere to the troposphere.

This study helped to identify the regions prone to higher air pollution exposure hence can identify areas at a greater health risk, the Ministry of Science and Technology said in a statement issued today. While INSAT-3D is a valuable Indian geostationary satellite to study ozone pollutions, India is lacking in space-based observation capability for other pollutants, for which an air quality monitoring indigenous satellite is needed, the statement added.