Linking fire incidence to chronic respiratory disease outcomes in Brazil’s Legal Amazon: an ecological study

Wildfire activity has intensified in the Brazilian Legal Amazon, increasing population-level exposure to air pollutants associated with respiratory morbidity and mortality. To examine the association between wildfire occurrence and deaths and disability-adjusted life years (DALYs) from chronic respiratory diseases in the states of the Legal Amazon. This ecological analytical study used secondary data from the Global Burden of Disease (GBD) database and the National Institute for Space Research (INPE – Queimadas Program). Annual absolute numbers of deaths and DALYs from chronic respiratory diseases were obtained for all ages and both sexes from 2011 to 2021. Annual wildfire foci counts were extracted from INPE. Associations between wildfire activity and health outcomes were assessed for each state using Spearman’s rank correlation (n = 11 annual observations per state). Pará presented the largest absolute burden of deaths and DALYs, followed by Maranhão and Mato Grosso, which also showed high wildfire activity. Most states exhibited increasing temporal trends in deaths and DALYs, while Maranhão showed declining deaths and Rondônia declines in both outcomes. A pronounced peak in wildfire activity and respiratory disease burden was observed in 2020. Significant positive correlations between wildfire foci and both deaths and DALYs were identified in Acre, Amazonas, Mato Grosso, and Rondônia, whereas no significant associations were observed in other states. Limitations: Findings are based on aggregated annual data and reflect ecological associations; causal inference and individual-level risk estimation are not possible. Wildfire activity is heterogeneously associated with the population-level burden of chronic respiratory diseases across the Legal Amazon, underscoring the importance of region-specific environmental and public health responses.