Department of Mining Engineering, National Institute of Technology (NIT), Rourkela 769008, India.
Department of Mining Engineering, Indian Institute of Technology (IIT), Kharagpur 721302, India.
Sci Total Environ. 2020 Nov 25;745:141024. doi: 10.1016/j.scitotenv.2020.141024. Epub 2020 Jul 19.
The Severe Acute Respiratory Syndrome-COronaVIrus Diseases 2019 (SARS-COVID-19) pandemic has posed a serious threat to human health (death) and substantial economic losses across the globe. It was however presumed that extreme preventive measures of entire lockdown in India might have reduced the air pollution level and therefore decreased the aerosol optical depth (AOD). The Moderate Resolution Imaging Spectroradiometer (MODIS)-based Multi-angle Implementation of Atmospheric Correction (MAIAC) daily AOD product was deployed to investigate the change in AOD level during lockdown phases across the Indian Territory as compared to the long-term mean AOD level (2000-2019) of the same periods. The key findings of the study revealed that AOD level over the Indian Territory is greatly reduced (45%) during the lockdown periods as compared to the long-term mean AOD level (2000-2019). Furthermore, a noteworthy negative AOD anomaly (6 to 37%) was observed across the four metropolitan cities in India during the entire lockdown period (25th March to 15th May 2020). However, coal mining regions of the various coalfields in India showed a positive anomaly (~+11 to 40%) during the lockdown periods due to ongoing mining operations. In a nutshell, the study results indicated a huge drop in the AOD level over Indian Territory during lockdown periods. It is expected that the pandemic can influence some policy decisions to propose air pollution control methods. Lockdown events possibly may play a crucial role as a potential solution for air pollution abatement in the future. It may not be uncommon in future when the governments may implement deliberately selective lockdowns at pollution hotspots to control the pollution level.
严重急性呼吸系统综合症-冠状病毒病 2019（SARS-COVID-19）大流行对全球人类健康（死亡）和重大经济损失构成严重威胁。然而，人们推测，印度实施全面封锁的极端预防措施可能降低了空气污染水平，从而降低了气溶胶光学厚度（AOD）。利用基于中等分辨率成像光谱仪（MODIS）的多角度大气校正实施（MAIAC）每日 AOD 产品，调查了与同期长期平均 AOD 水平（2000-2019 年）相比，印度境内封锁期间 AOD 水平的变化。研究的主要发现表明，与长期平均 AOD 水平（2000-2019 年）相比，印度领土上空的 AOD 水平在封锁期间大幅降低（约 45%）。此外，在整个封锁期间（2020 年 3 月 25 日至 5 月 15 日），印度四个主要城市的 AOD 异常值明显为负（约-6%至-37%）。然而，由于正在进行采矿作业，印度各个煤田的采煤区在封锁期间的 AOD 异常值呈正（约+11%至+40%）。简而言之，研究结果表明，印度领土上空的 AOD 水平在封锁期间大幅下降。预计大流行将影响一些政策决策，以提出空气污染控制方法。封锁事件可能在未来作为减少空气污染的潜在解决方案发挥关键作用。在未来，政府可能会故意在污染热点地区实施有选择性的封锁以控制污染水平，这种情况可能并不罕见。
