Background: This work describes the changes of the air quality and the health implications caused by the lockdown of the first-wave provoked by the SARS-CoV-2 pandemic. Air pollutants were studied in 83 locations in Southern Spain. The study covered urban and industrial gases, NO 2 , CO, SO 2 , H 2 S and O 3 , and also PM 10 and PM 2.5 particles.MethodsIt was evaluated the increase and decrease of concentrations during the state of alarm declared on 14 th March. Pearson correlations for air pollutants, meteorological factors, vehicular traffic densities (VTDs) and data of infections and deaths caused by the COVID-19 disease were also assessed.ResultsIt was found a clear reduction in carbon monoxide (-25% to -83%), particulate matter (-21% to -42%) and mainly nitrogen dioxide (-55% to -81%) in trafficked areas during the lockdown, reducing cardiovascular and respiratory problems. CO, SO 2 and H 2 S increased (+26 to 34%, +68 to +85% and +32 to +84%) at industrial locations. O 3 increased along the lockdown period coinciding with reductions in NO 2 and CO (r = -0.90 and -0.81). This ozone rising constitute the ozone lockdown effect (OLE), increasing the risk of pneumonia hospital admissions. Regarding traffic, Pearson coefficients between ozone and VTDs were higher during lockdown than pre-lockdown period, and in the most trafficked areas a reduction in PM 10 and PM 2.5 levels was observed, contributing this also to the OLE.ConclusionsEffects of ozone on COVID-19 disease was revealed by the graphic associations and correlations found between O 3 levels and infection cases and deaths, which were remarkable, constituting in this case the ozone COVID effect (OCE): when concentrations of O 3 increase, the incidence of the disease is higher;when O 3 falls, infection cases are reduced.
Impact of COVID-19 Lockdowns on Air Quality and Health. Association between Concentrations of Tropospheric Ozone and Infection Cases and Deaths in Spain