Particulate matter pollution and the COVID-19 outbreak: results from Italian regions and provinces

Introduction: Particulate matter exposure has been associated with the appearance and severity of several diseases, including viral infections. The aim of this study was to investigate whether coronavirus disease 2019 (COVID-19) cases and deaths across Italian regions and provinces in March 2020 were linked to past exposure to fine and coarse particulate matter (namely, PM2.5 and PM10, respectively). Material and methods: Geographical distributions of COVID-19 cases and deaths (105,792 and 12,428, respectively, up to 31st March 2020), PM2.5 and PM10 exposure, and demographic characteristics were extracted from publicly accessible databases. Adjusted regression models were performed to test the association between particulate matter exposure in different Italian regions and provinces and COVID-19 incidence proportions and death rates. Results: A heterogeneous distribution of COVID-19 cases/deaths and particulate matter exposure was observed in Italy, with the highest numbers in Northern Italy regions and provinces. Independent associations between regional PM2.5/PM10 exposure and COVID-19 incidence proportion and death rate were observed (COVID-19 incidence proportion: beta = 0.71, p = 0.003, beta = 0.61, p = 0.031, respectively; COVID-19 death rate: beta = 0.68, p = 0.004 and beta = 0.61, p = 0.029, respectively). Similarly, PM2.5/PM10 exposures were independently associated with COVID-19 incidence proportion (beta = 0.26, p = 0.024 and (beta = 0.27, p = 0.006, respectively) at the provincial level. The number of days exceeding the provincial limit value of exposure to PM10 (50 mu g/m(3)) was also independently associated with the COVID-19 incidence proportion (beta = 0.30, p = 0.008). Conclusions: Exposure to PM2.5 and PM10 is associated with COVID-19 cases and deaths, suggesting that particulate matter pollution may play a role in the COVID-19 outbreak and explain the heterogeneous distribution of COVID-19 in Italian regions and provinces.