Wildfire-related PM 2.5 and cardiovascular mortality: A difference-in-differences analysis in Brazil *

Brazil has experienced unprecedented wildfires recently. We aimed to investigate the association of wildfirerelated fine particulate matter (PM 2.5 ) with cause -specific cardiovascular mortality, and to estimate the attributable mortality burden. Exposure to wildfire -related PM 2.5 was defined as exposure to annual mean wildfirerelated PM 2.5 concentrations in the 1 -year prior to death. The variant difference -in -differences method was employed to explore the wildfire -related PM 2 . 5 -cardiovascular mortality association. We found that, in Brazil, compared with the population in the first quartile (Q1: <= 1.82 mu g/m 3 ) of wildfire -related PM 2.5 exposure, those in the fourth quartile (Q4: 4.22-17.12 mu g/m 3 ) of wildfire -related PM 2.5 exposure had a 2.2% (RR: 1.022, 95% CI: 1.013-1.032) higher risk for total cardiovascular mortality, 3.1% (RR: 1.031, 95% CI: 1.014-1.048) for ischaemic heart disease mortality, and 2.0% (RR: 1.020, 95% CI: 1.002-1.038) for stroke mortality. From 2010 to 2018, an estimation of 35,847 (95% CI: 22,424-49,177) cardiovascular deaths, representing 17.77 (95% CI: 11.12-24.38) per 100,000 population, were attributable to wildfire -related PM 2.5 exposure. Targeted health promotion strategies should be developed for local governments to protect the public from the risk of wildfirerelated cardiovascular premature deaths.