Assessment of COVID-19 lockdown impact on PM10 and PM2.5 concentrations in the Mexico City Metropolitan Area

PM10 and PM2.5 concentrations are regularly monitored because they cause adverse effects on human health. The concentrations of PM10 and PM2.5 vary within a city due to land use, the amount of traffic, and pollution sources. As the COVID-19 pandemic spread around the world, lockdowns were enacted to stop the spread of the virus. These lockdowns meant reduced mobility and the halt of certain economic activities which had an impact on air pollution sources. In this paper, we assess the effect of the lockdown enacted in April-May 2020 in the Mexico City Metropolitan Area on PM10 and PM2.5 concentrations, using statistical analysis tools. MODIS-derived aerosol optical depth is used to assess the change of aerosols spatial distribution during the lockdown. Furthermore, a Mann-Whitney test is applied to PM10 and PM2.5 data from ground-based monitoring stations to evaluate the effects of lockdown. A general reduction of 20 % of PM10 and 10 % in PM2.5 was found. Overall, a 15 % reduction in particulate matter was found in Mexico City due to lockdown.