Environmental factors and mortality by COVID-19 in Brazil

Abstract

The COVID-19 pandemic, caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), started its outbreak in Brazil in mid-February 2020.

Methods: This ecological study aimed to identify relationships between COVID-19 mortality rates in 27 cities in Brazil and environmental factors, namely climate and air quality. To characterize the cities’ climate and air pollution background, daily data from 2015 to 2020 of temperature and tropospheric column NO2 from OMI (Ozone Monitoring Instrument), were used. Negative binomial regression was applied in four different moments of the epidemics: 50, 75, 100 and 125 days after the first case registered in each city, accounting for the influence of confounding factors related to demographic characteristics, prevalence of comorbidities and mobility restriction.

Results: The principal results show that NO2 concentrations in São Paulo and Rio de Janeiro metropolitan areas decreased in the first month of the epidemics. Among the environmental factors analyzed, temperature and NO2 exposure were positively associated with deaths by COVID-19 in the 100th epidemic day, with mortality rate rates (MRR) of 1.13 (95% CI: 1.07-1.20) and 1.03 (95% CI: 1.02-1.03), respectively. On the other hand, the percentage of young people was negatively associated with deaths (MRR=0.72, 95% CI: 0.67-0.76).

Conclusion: The positive association between temperature and deaths reflect the fast spread of COVID-19 in warm tropical cities, so that the likely protective effect of temperature on virus transmissivity was overwhelmed by the influence of socioeconomic conditions, access to health care, cultural aspects and ineffective social distancing policies.