App. Geog.151 (2023)

Analysis shows that lockdown air quality across India increased photosynthetic activity and surface greenness1. Compared to pre-lockdown, levels of atmospheric fine particles and suspended droplets plummeted during lockdown.

The improved air quality allowed more sunlight to reach croplands and forests, accelerating photosynthesis, and enhancing crop yields and terrestrial carbon uptake.

Researchers at the Indian Institute of Technology Kharagpur in West Bengal analysed satellite data and air quality in pre-lockdown periods between 2017 and 2019, during lockdown in 2020 and post-lockdown in 2021.

They found that during lockdown the surface greenness of croplands increased by 14.5%, which was higher than that of forests, at 7.9%. The increase in croplands’ photosynthetic activity was about four times higher than that of forests.

Aerosol optical depth – the vertical column of dust particles and haze that blocks sunlight through absorption or scattering – decreased notably during lockdown. The team, led by Jayanarayanan Kuttippurath, also detected a significant drop in sulfur dioxide levels during lockdown compared to post-lockdown.

Lockdown reduced pollution from all sources, except domestic. This enhanced air quality extended the growing season by 32 days in some of the croplands in the Indo-Gangetic Plain, and north-west and south India.

The researchers say that these findings will help policymakers draft laws to improve air quality. This will protect public health, mitigate climate change, and ensure regional and global food security by boosting crop yields.