Suchergebnisse

To mitigate the impacts of the pandemic of coronavirus disease 2019 (COVID-19), the Indian government implemented lockdown measures on March 24, 2020, which prohibit unnecessary anthropogenic activities and thus leading to a significant reduction in emissions. To investigate the impacts of this lockdown measures on air quality in India, we used the Community Multi-Scale Air Quality (CMAQ) model to estimate the changes of key air pollutants. From pre-lockdown to lockdown periods, improved air quality is observed in India, indicated by the lower key pollutant levels such as PM 2.5 (−26 %), maximum daily 8-h average ozone (MDA8 O 3 ) (−11 %), NO 2 (−50 %), and SO 2 (−14 %). In addition, changes in these pollutants show distinct spatial variations with the more important decrease in northern and western India. During the lockdown, our results illustrate that such emission reductions play a positive role in the improvement of air quality. Significant reductions of PM 2.5 and its major components are observed especially for secondary inorganic aerosols with the decreasing rates up to 92 %, 57 %, and 79 % for nitrate (NO 3 − ), sulfate (SO 4 2− ), ammonium (NH 4 + ), respectively. On average, the MDA8 O 3 also decreases 15 % during the lockdown period although it increases sparsely in some urban locations, which is mainly due to the lower NO x and VOCs emissions. More aggressive and localized emissions control strategies should be implemented in India to mitigate air pollutions in the future.