Temporary reduction in fine particulate matter due to ‘anthropogenic emissions switch off’ during COVID 19 lockdown in Indian cities

•COVID-19 lockdown reduced PM2.5 concentrations in five Indian cities by up to 54%.•PM2.5 reduction in Delhi was similar to that of other Asian and European cities.•Modelling revealed fewer extreme PM2.5 values during the lockdown in all cities.•Spatial distribution of AOD showed a general decrease in aerosol loading.•PM2.5 reductions prevented ∼630 premature deaths, valued at 0.69 billion USD.