COVID-19 Lockdown: Lessons learnt using multiple air quality monitoring station data from Kolkata city in India

On March 16, 2020, Kolkata megacity in India announced partial lockdown due to COVID-19 crisis. This study presents an analysis for multiple pollutants with special focus on NO2 and O3 based data from different monitoring stations located across city the period 16 March- 17 May 2020 compared pre-lockdown period. Most significant reduction was observed concentration of nitrogen dioxide (NO2) (- 76.8%), volatile organic compounds (VOCs) 69.5%), PM10 64.6%) PM2.5 60.9%). A lower percentage found CO, sulfur (SO2) ammonia (-48.6%, - 41.7% – 41.1% respectively). However, during lockdown, phase-1, phase-2 phase-3, surface-level ozone (O3) has changed respectively by 31.72%, 31.13%, -14.28% -14.05% which resulted overall increase 8.17% entire The air quality index (AQI) usually remains poor or very poor, even period, failed attain ‘good’ standard. needs attention human health impact assessment public management. We recommend additional be drawn towards stickiness had adverse went up highlight some major policy implications trends combat pollution along climate co-benefits shifting transport fuel related infrastructure.