Estimating ambient air pollution mortality and disease burden and its economic cost in Barcelona

Background: The new WHO air quality guidelines indicate that the air pollution disease burden is greater than previously reported. We aimed to estimate the air pollution disease burden and its economic cost in Barcelona to inform local action.Methods: We used a quantitative health impact assessment to estimate the non-accidental mortality and incidence of childhood asthma and lung cancer attributable to long-term air pollution exposure in the city of Barcelona (Spain) in 2018-2019. We used the population weighted mean of PM2.5 and NO2 assigned at the geocoded address during the study period and the 2021 WHO air quality guidelines as counterfactual scenario to estimate new annual cases attributable to each pollutant separately and combined. We estimated the social cost of attributable deaths and the health care cost of childhood asthma and lung cancer attributable cases. We also estimated attributable mortality by city district and the mortality avoidable by achieving the WHO air quality interim targets.Results: Mean exposure was 17 mu g/m(3) for PM2.5 and 39 mu g/m3 for NO2. Total combined air pollution attributable mortality was 13% (95%CI = 9%-17%), corresponding to 1,886 deaths (95%CI = 1,296-2,571) and a social cost of euro 1,292 million (95%CI = 888-1,762) annually. Fifty-one percent (95%CI = 21%-71%) and 17% (95%CI = 7%-29%) of new cases of childhood asthma and lung cancer were attributable to air pollution with a health care cost of euro 4.3 and euro 2.7 million, respectively. Achieving the first unmet WHO air quality interim targets for PM2.5 and for NO(2 )would avoid 410 deaths and euro 281 million annually.Conclusion: Air pollution in Barcelona represents a huge disease and economic burden, which is greater than previous estimates. Much stronger measures to reduce PM2.5 and NO2 levels are urgently needed. Until the WHO air quality guidelines are met in the city, achieving each WHO air quality interim targets would avoid hundreds of deaths each year.