PM_2.5 exposures increased for the majority of Indians and a third of the global population during COVID-19 lockdowns: a residential biomass burning and environmental justice perspective

Abstract

In response to the emergence of COVID-19 during Spring 2020, many countries implemented nationwide lockdowns and mandatory stay-at-home orders, which resulted in historically clean ambient air quality. However, in many parts of the world, biomass burning for cooking is a common activity, and in India specifically, it has been implicated as the leading contributor to indoor and ambient PM2.5, and its activity was not stopped and likely increased during lockdowns. Here, we first estimate baseline and lockdown PM2.5 exposures specific to India using new, nationwide time-use survey data coupled with fine-scale PM2.5 estimates within various microenvironments. We then extend this framework to estimate the population globally that will have experienced higher PM2.5 exposures during lockdowns, due both to an increase in residential biomass burning activity as well as the entire day being spent in the usually more-polluted home environment. 65% of Indians, the percent that uses biomass fuels for cooking, were exposed to higher PM2.5 levels during the lockdown compared to their modeled baseline exposures, with the average modeled exposure increasing by 13% (95% distribution: 8-26) (from 116 (82-157) to 131 (104-170) µg m-3). We further leverage this exposure framework to present India’s most comprehensive, to date, PM2.5 exposure disparity and environmental justice assessment; although women were still exposed to the highest levels of PM2.5 during the lockdown (from 135 (91-191) µg m-3 baseline to 147 (106-200) µg m-3 during the lockdown; 8.8% (5-18) increase), the demographic groups that experienced the highest exposure increases were working-age men and school-age children, whose average modeled exposures increased by 24% (18-48) (from 88 (63-118) to 108 (94-139) µg m-3) and 18% (8-31) (from 98 (75-134) to 115 (98-145) µg m-3), respectively. Globally, we conservatively estimate that 34.5% (21-51) of the global population observed increased PM2.5 exposures during COVID-19 lockdowns, concentrated in regions with high biomass usage. There have been a number of clean-cooking initiatives introduced in India and throughout the world to replace biomass cookstoves, but the finding that PM2.5 exposures increased for the majority of Indians and a third of the global population– driven largely by residential biomass burning for cooking – during a period of historically clean ambient air quality, re-emphasizes the urgent need to further address clean cooking interventions to reduce PM2.5 exposures and in turn improve health outcomes.