Impacts of droughts on biomass burning emissions, air quality, and public health in the Amazon

Wildfires in the Amazon, increasingly influenced by climate variability and anthropogenic activities, pose severe environmental and health challenges. While drought events amplify fire activity and emissions, the cascading effects of droughts and deforestation on air quality and health remain underexplored. This study addresses this gap by combining satellite observations of fire activities with the Global Fire Emissions Database (GFEDv4 s) and the chemical transport model, GEOS-Chem High Performance (GCHP) to quantify the impacts of droughts and deforestation on fire emissions, air quality, and health risks from 2010–2015. “Fire-on” and “fire-off” simulation reveal that biomass burning dominates dry-season (July–November) air quality, contributing 34.0 % (32.0 %–35.5 %) to regional CO and PM2.5 and 29.0 % (28.3 %–29.7 %) for ozone in non-drought years. These contributions increase to 55.4 % (44.1 %–76.7 %) for CO and PM2.5 and 42.3 % (36.2 %–47.8 %) for ozone during drought years. Significant correlations between pollutant levels and drought intensity reflect a climate-driven amplification of fire impacts. Using the Global Exposure Mortality Model (GEMM) and exposure-response relations, we estimate that fire-induced PM2.5 and ozone increase premature mortality by 6.0 % and 18.6 % in non-drought years, which rise to 8.9 % and 24.4 % during drought years. These findings underscore the critical roles of droughts in exacerbating fire emissions and health risks, even under stable deforestation rates. This study highlights the urgent need for integrated wildfire management and climate adaptation strategies to protect public health and achieve sustainability goals.