The role of tropospheric ozone in flagging COVID-19 pandemic transmission

COVID-19 pandemic outbreak, caused by the SARS-CoV-2 virus, affected millions of people worldwide causing hundreds of thousands of related fatalities. It is crucial to understand why the virus transmission seems to spread more easily in some regions than others. The residuals, with respect to the modeled COVID-19 per-day hospitalized patients in intensive care unit, are correlated to the meteorological and air-pollutant variables in four major metropolitan areas in Italy during a strict lockdown implemented by the Italian government, making the analysis independent from socio-economic factors. The results show that COVID-19 pandemic-related infections are slowed down by higher tropospheric ozone concentrations and eased by the atmospheric particulate. We quantitatively assessed that higher levels of tropospheric ozone, already proven effective against viruses and microbial contaminants, play a role in flagging COVID-19 pandemic transmission. Because the tropospheric ozone production is depending, among others, by air-quality and sunlight, this can explain why the virus is spreading in different ways.