COVID-19 lockdowns cause global air pollution declines

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 (NO 2 : 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 (O 3 : 4%; 95% CI: −2 to 10%) in 34 countries during lockdown dates up until 15 May. Except for ozone, satellite…