Reduction in NO2-attributable mortality and morbidity due to the COVID-19 lockdown in Spain

Abstract:

Acute exposure to outdoor air pollution is an important risk factor contributing to morbidity and mortality. Since the onset of the COVID-19 pandemic, air quality has temporarily improved in the locations where the population has been confined to reduce the transmission of the disease. Spain is the third European country with the highest impact in terms of cases per million (513 as of June 8th), and second in deaths per million (58.1). We have quantified the potential reduction in the non-COVID-19 mortality and cardiovascular hospitalizations attributable to the short-term effects of NO₂ during the COVID-19 lockdown in the main Spanish cities. Based on quasi-Poisson regression models, we first estimated province-specific associations between daily NO₂ values and both mortality and cardiovascular hospitalizations during the period 2013-2018. We then estimated the “business-as-usual” (BAU) concentrations of NO₂ that would have occurred without the lockdown in each province based on a machine-learning meteorology-normalization technique. Finally, we used the obtained exposure-response functions to transform the daily (i) observed and (ii) BAU NO₂ time-series during the lockdown period into daily NO₂-attributable mortality and cardiovascular hospitalizations time-series, and we computed the difference BAU minus observations to obtain the associated reductions. Our findings provide useful insight on the potential short-term health benefits of reducing air pollutant emissions from road traffic and economic activities, including a better understanding of reported reductions in hospital admissions from heart attacks, strokes and other cardiovascular diseases.