With the rapid spread of COVID-19 related cases globally, national governments took different lockdown approaches to limit the spread of the virus. Among them, the Government of India imposed a complete nationwide lockdown starting on March 25, 2020. This presented a unique opportunity to explore how a complete standstill in regular daily activities might impact the local environment. In this study, we have analyzed the change in the air quality levels stemming from the reduced anthropogenic activities in one of the most polluted cities in the world, the Delhi Metropolitan Region (DMR). We analyzed station-level changes in particulate matter, PM₁₀ and PM_2.5, across the DMR between April 2019 and 2020. The results of our study showed widespread reduction in the levels of both pollutants, with substantial spatial variations. The largest decreases in particulate matter were associated with industrial and commercial areas. Highest levels of PM₁₀ and PM_2.5 were observed near sunrise with little change in the time of maximum between 2019 and 2020. The results of our study highlight the role of anthropogenic activities on the air quality at the local level.

随着 COVID-19 相关病例在全球范围内的迅速传播，各国政府采取了不同的封锁措施来限制病毒的传播。其中，印度政府从 2020 年 3 月 25 日开始在全国范围内实施全面封锁。这提供了一个独特的机会来探索日常活动完全停止可能如何影响当地环境。在这项研究中，我们分析了由于世界上污染最严重的城市之一德里大都市区 (DMR) 的人为活动减少而导致的空气质量水平变化。我们分析了站级颗粒物、PM ₁₀和 PM _2.5的变化，跨越 2019 年 4 月至 2020 年 4 月的 DMR。我们的研究结果表明，这两种污染物的水平普遍下降，空间变化很大。颗粒物的最大减少与工业和商业领域有关。在日出附近观测到最高水平的 PM ₁₀和 PM _2.5，在 2019 年至 2020 年之间的最大值时间几乎没有变化。我们的研究结果强调了人为活动对当地空气质量的影响。