The lockdown response to coronavirus disease 2019 (COVID-19) has caused an unprecedented reduction in global economic and transport activity. We test the hypothesis that this has reduced tropospheric and ground-level air pollution concentrations, using satellite data and a network of >10,000 air quality stations. After accounting for the effects of meteorological variability, we find declines in the population-weighted concentration of ground-level nitrogen dioxide (NO₂: 60% with 95% CI 48 to 72%), and fine particulate matter (PM_2.5: 31%; 95% CI: 17 to 45%), with marginal increases in ozone (O₃: 4%; 95% CI: −2 to 10%) in 34 countries during lockdown dates up until 15 May. Except for ozone, satellite measurements of the troposphere indicate much smaller reductions, highlighting the spatial variability of pollutant anomalies attributable to complex NO_x chemistry and long-distance transport of fine particulate matter with a diameter less than 2.5 µm (PM_2.5). By leveraging Google and Apple mobility data, we find empirical evidence for a link between global vehicle transportation declines and the reduction of ambient NO₂ exposure. While the state of global lockdown is not sustainable, these findings allude to the potential for mitigating public health risk by reducing “business as usual” air pollutant emissions from economic activities. Explore trends here: https://nina.earthengine.app/view/lockdown-pollution.

针对 2019 年冠状病毒病 (COVID-19) 的封锁措施导致全球经济和运输活动空前减少。我们使用卫星数据和超过 10,000 个空气质量站网络来检验这一假设，即这降低了对流层和地面空气污染浓度。考虑到气象变化的影响后，我们发现地面二氧化氮（NO ₂ ：60%，95% CI 48 至 72%）和细颗粒物（PM _2.5 ：31%）的人口加权浓度下降截至 5 月 15 日的封锁期间，34 个国家的臭氧略有增加（O ₃ ：4%；95% CI：-2 至 10%）。除臭氧外，对流层的卫星测量显示减少幅度要小得多，突出显示了由于复杂的氮_氧化物化学和直径小于 2.5 µm 的细颗粒物 (PM _2.5 ) 的长距离输送而造成的污染物异常的空间变异性。通过利用 Google 和 Apple 的移动数据，我们找到了全球车辆运输量下降与环境_二氧化氮暴露减少之间存在联系的经验证据。虽然全球封锁的状态是不可持续的，但这些发现暗示了通过减少经济活动中“一切照旧”的空气污染物排放来减轻公共卫生风险的潜力。在这里探索趋势：https://nina.earthengine.app/view/lockdown-pollution。