Dispersion of PM2.5 particles emitted by the waste dump fire in the city of Guanajuato, Mexico

Abstract Air pollution is the most significant environmental health risk, and the chemical composition of PM 2.5 has the greatest impact on its effects on human health. While PM 2.5 pollution has been widely studied, little attention has been given to the role of landfill fires in shaping PM 2.5 composition and dispersion in medium-sized cities with complex topographies. This study integrates the physical and chemical characterization of PM 2.5 (potassium, chlorine, and irregular morphology) with AERMOD dispersion modeling to assess exposure during a landfill fire in Guanajuato, Mexico. The maximum monthly average concentration was recorded in May at 22.4 µg m⁻ 3 , while the 24-h average exceeded the allowable limit of 33 µg m⁻ 3 during the days of the landfill fire, reaching 50 µg m⁻ 3 . The annual average concentration (13.4 µg m⁻ 3 ) also exceeded the 10 µg m⁻ 3 guideline. AERMOD simulations reproduced observed patterns, confirming northeastward dispersion toward the city hillside. Based on the 12-h moving average during the fire (45 µg m⁻ 3 ), residents were exposed to poor air quality and elevated risks of respiratory and cardiovascular diseases, stroke, and lung cancer. These results provide novel evidence of the contribution of landfill fires to urban PM 2.5 pollution and associated health risks, offering valuable insights for air quality management and public health protection in cities with similar environmental conditions.