COVID-19 Outbreak in Lombardy, Italy: An Analysis of the Short-Term Role of Air Pollution and Meteorological Factors

Background: Short-term exposure to air pollution, as well as to climate variables could be linked to a higher incidence of respiratory viral diseases. The objective of the study is to assess the short-term impact of air pollution and climate on COVID19 incidence in Lombardy (Italy), during the initial outbreak. Methods: The daily number of COVID19 cases in Lombardy from February 25th to March 10th 2020, and the daily average concentrations of particulate matter (PM10, PM2·5), O3, SO2, and NO2 together with climate variables (temperature, relative humidity – RH%, wind speed, precipitation), were analyzed. A mixed model with a logarithm transformation as link function was applied to evaluate the relationship between all the variables. Additionally, change points (Break Points; BP) in the relationship between incident cases and air pollution or climatic factors were estimated. Findings: The analysis showed a two-phase effect of PM10 on COVID19 incidence, with a negative association at the beginning of the examined period and a positive one later on, while a positive relationship was observed for O3. The COVID19 spread in Lombardy showed to be influenced positively by RH%, and negatively by wind speed. A BP at 40 µg/m3 was observed for PM10 at lag8, and for O3 at lags 3-8 and 10. Interpretation: PM10, O3, RH% and wind speed showed a short-term association with the COVID19 incidence. Air pollution and climate conditions should be considered as part of an integrated approach when containment measures against SARS-CoV-2 are adopted. Funding: The study did not receive any fund. Declaration of Interests: The Authors declare no conflict of interest.