Impact of PM_2.5 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.m³ (Palmas, 2020) to 49.69 µg.m³ (Porto Velho, 2021), exceeding the WHO guideline of 5 µg.m³ in all cities. Most capitals experienced over 100 days per year above the 15 µg.m³ 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 5472 (95 % CI: 4595-6711) deaths from circulatory diseases and 2621 (95 % CI: 864-4278) 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.