COVID-19 mortality rates in South America related to environmental factors

The COVID-19 pandemic started its outbreak in South America in mid-February 2020, causing hundreds of thousands of deaths within a period of 8 months. This ecological study aimed to investigate whether environmental factors like air quality and climate could explain the variability in COVID-19 mortality rate across 36 South American cities spanning different climate regimes. The cities’ climate and air pollution background were characterised using daily data from surface weather stations and tropospheric column NO2 from OMI (Ozone Monitoring Instrument). Results indicate a drop in NO2 concentrations in six metropolitan areas in the first month of the epidemics, following the mobility restrictions. Temperature and NO2 exposure were positively associated with deaths by COVID-19, with mortality rate ratios (MRR) of 1.25 (95% CI 1.20–1.30) and 1.02 (95% CI 1.01–1.03), respectively, in the 100th epidemic day. The positive association between temperature and deaths related to COVID-19 suggest that the likely protective effect of temperature on virus spread was overwhelmed by the influence of socioeconomic conditions, access to health care, cultural aspects and effectiveness of social distancing policies.