PM10 and NO2 Air Pollution and Evolution of COVID-19 Cases in Romania

Objectives:Based on the correlation between air pollution and COVID-19 incidence/mortality already existing in the literature, we aimed to develop a study to investigate the link between the average level of PM10 (particulate matter 10 - particulate matter 10 microns in diameter) and NO2 (nitrogen dioxide) concentration over five years and the cumulative incidence of COVID-19 cases per 1000 people in Romania. Methods: To assess PM10 and NO2 exposure, we determined the average value of annual PM10 and NO2 concentration for each city over five years (2015-2019). For this purpose, the average of annual PM10 and NO2 concentrations collected from monitoring stations in selected cities was calculated. Then, the annual values over five years were averaged to finally obtain the average PM10 and NO2 concentration for each city. Data on the cumulative number of confirmed cases of COVID-19 up to the 28th of September 2020 were provided by the National Centre for Surveillance and Control of Communicable Diseases (CNSCBT) of the National Institute of Public Health (INSP). The study used the cumulative incidence/hour per 1000 population on 28.09.2020. Results:According to Law no. 104/2011, the annual permissible limit value of PM10 concentration of 40 μg/m³ was not exceeded in any of the 43 cities in our study. The average for all cities was 24.0±4.8 ìg/m³, with a minimum value of average PM10 concentration of 13.9 μg/m3 measured in Alba Iulia and a maximum value of 39.1 μg/m³ in Iasi. The regression model shows that, in Bucharest, 77.9% of the variation in case incidence is explained by the variation in PM10 concentration. In order to find the number of new cases that would correspond to a cumulative incidence of 0.166, taking as an example one of the districts with a population of 259,084, the above regression model shows that an increase in the average PM10 concentration by one unit is associated with 43 new cases. Conclusion:The study demonstrates that an exposure of the population to particulate matter in atmospheric air, at low values, below the permissible limit values but for a long time (the follow-up period in our study was five years, between 2015 and 2019), can have effects on the health status of the population, which becomes much more vulnerable to external agents, in our case pathogenic microorganisms (viruses).