Impact of PM2.5 on cardiorespiratory mortality: A study in the capitals of Brazilian amazon rainforest

Wildfire-related air pollution represents an escalating health threat in the Brazilian Amazon, where fine particulate matter (PM 2.5 ) concentrations frequently exceed safe levels (5 µg/m -3 ). This study quantified long-term PM 2.5 exposure and its impact on cardiorespiratory mortality across the seven Amazonian capitals, Belém, Boa Vista, Macapá, Manaus, Palmas, Porto Velho, and Rio Branco, between 2018 and 2023. In addition, disease-specific outcomes including chronic obstructive pulmonary disease (COPD), lung cancer (LC), and ischemic heart disease (IHD) were assessed. Daily PM 2.5 data were obtained from the CAMS reanalysis, and mortality records from the Brazilian Health Data Platform. Health impacts were estimated using the WHO AirQ+ log-linear model. Annual mean PM 2.5 ranged from 10.47 µg.m 3 (Palmas, 2020) to 49.69 µg.m 3 (Porto Velho, 2021), exceeding the WHO guideline of 5 µg.m 3 in all cities. Most capitals experienced over 100 days per year above the 15 µg.m 3 daily guideline, and significant correlations were observed between wildfire counts and PM 2.5 in Porto Velho (r=0.24) and Rio Branco (r=0.21). Between 2018 and 2023, approximately 5,472 (95% CI: 4,595–6,711) deaths from circulatory diseases and 2,621 (95% CI: 864–4,278) from respiratory diseases were attributable to PM 2.5 exposure. COPD accounted for 627 (95% CI: 462–781) deaths, LC for 427 (95% CI: 314–534), and IHD for 304 (95% CI: 150–467). The highest burdens occurred in Belém, Manaus, and Porto Velho. These findings demonstrate that persistent smoke from seasonal fires has become a critical environmental health crisis in the Amazon, demanding urgent action to prevent deforestation, reduce emissions, and protect population health.