Air Pollution and Health Impacts of Wildfire Seasons: Insights from Northern Portugal

Abstract Wildfires emit significant amounts of pollutants into the atmosphere, which can cause a range of health effects, from acute symptoms to increased emergency visits, hospital admissions, and even mortality in the general population. This study aimed to characterize, for the first time, the associations between wildfire season with indicators of public human health surveillance in the Northern region of Portugal (2019–2022). Daily air pollutant data [particulate matter with aerodynamic diameter less than 10 µm (PM₁₀) and 2.5 µm (PM₂.₅), ozone (O₃), and itrogen dioxide (NO₂)], monthly emergency room visits, and regional expenses with medication dispensing were characterized and mortality impacts were estimated. Wildfire season was responsible for higher PM₁₀ and PM₂.₅ (up to + 90%), O₃ (up to + 51%), and NO₂ (up to + 39%); some days (up to 8%) surpassed limits established by national regulations and/or WHO guidelines. The total burned area correlated with monthly levels of PM₁₀, PM₂.₅, and O₃ (0.467 < r < 0.943; p ≤ 0.039). Wildfire season months presented more emergency visits to urgent care (up to + 128%; p > 0.05) and regional monthly health costs due to outpatient medication for blood volume and electrolyte imbalance (+ 12–31%; p > 0.05). During wildfire season, the number of urgent pediatric visits correlated with O₃ levels ( r = 0.606, p = 0.013). During large forest fires (> 100 hectares), a maximum of 36 and 330 estimated deaths were attributed, respectively, to short-term and long-term exposure to PM₁₀, PM₂.₅, O₃, and NO₂ above WHO guidelines. The findings highlight the need to improve wildfire management and public health policies, including through a stronger engagement of the general population, and promote the implementation of more effective preventive and mitigation strategies to protect the health of affected communities during wildfire season.