Effects of the quarantines and activity restrictions related to the coronavirus disease (COVID-19) on air quality in Latin America's cities

Air pollution represents a major environmental health hazard. According to the World Health Organization (WHO), it is responsible for 300,000 deaths every year in the Americas, and 9 in every 10 people are breathing polluted air at this very moment. The air pollutants that are most harmful to human and environmental health are coarse particulate matter (PM10) and fine particulate matter (PM2.5), nitrogen dioxide (NO2) and sulfur dioxide (SO2). The concentrations of these pollutants in city air are then determined by the environmental conditions prevailing in each case. As multiple factors are in play, it is impossible to attribute any reduction in concentrations exclusively to the activity restrictions and quarantines imposed to deal with the current COVID-19 pandemic. The measures adopted by the region’s national or local governments to limit the spread of the COVID-19 pandemic include quarantines, lockdown orders and the reduction or cessation of economic activities, which have impacted production levels and human mobility. As there is also anecdotal evidence that air quality has improved, this document presents the results of a statistical investigation into the concentrations of these three key pollutants in selected cities3 of the region that are home to about 14% of Latin America’s urban population: Bogotá, Lima, Mexico City, Monterrey (Mexico), Quito, Santiago and São Paulo (Brazil) to determine whether the measures deployed have in fact contributed to better air quality.