Emergency visits and mortality caused by ischemic heart disease attributable to fine particulate matter during the COVID-19 pandemic in Chile

Background. - A reduction in PM2.5 was reported worldwide during the COVID-19 pandemic lockdown. Santiago, the capital and largest city of Chile, is characterized by high concentrations of PM2.5, being vehicular traffic a major contributor. Its air quality was improved as a collateral effect of the lockdown imposed in the second quarter of 2020. We aimed at highlighting an ensuing decrease of emergency visits for treatment of acute myocardial infarction (AMI) and deaths due to ischemic heart diseases (IHD) attributable to PM2.5, comparing equivalent periods in 2019 and 2020. Methods. - In Santiago, air quality monitoring is carried out by nine monitors located in nine communes: Cerro Navia, Cerrillos, El Bosque, Pudahuel, Independencia, La Florida, Quilicura, downtown Santiago and Las Condes (ranked from highest to lowest in terms of multidimensional poverty).We described average daily PM2.5 concentration with time-series graphs of means and standard deviations. AMI-emergency visits and IHD deaths were reported for each quarter by year. To estimate the impact of PM2.5 excess, we estimated the population attributable fractions (PAF) for AMI-emergency visits and IHD-related deaths. Results. - Daily average PM2.5 decreased in eight out of nine communes in Santiago. However, the reduction was significant in only three communes. AMI-emergency visits and IHD-related deaths attributable to PM2.5 decreased slightly but significantly in these three communes. The PAF in other communes remained similar to 2019 despite the lockdown. Conclusions. - A significant reduction of PM2.5 PAF potentially responsible for AMI emergency visits and IHD deaths was observed only in communes with a significant reduction of the daily average concentration of PM2.(5) during the COVID-19 pandemic. (C) 2021 Elsevier Masson SAS. All rights reserved.