Relationship between forest fires and air quality: a study of particulate matter in localities distant from the main emission source.

Wildfires represent a growing threat to air quality in fire-prone regions; however, the spatiotemporal dynamics of pollutant dispersion to distant localities remain inadequately characterized. This study quantifies particulate matter concentrations (PM1.0, PM2.5, PM10) in localities distant from the February 2024 Valparaíso wildfire, evaluating their spatiotemporal variation and association with fire intensity and meteorological parameters using a network of low-cost sensors. Four PurpleAir sensors distributed along the Valparaíso-Santiago corridor (70-120 km) were integrated with meteorological stations and satellite-derived Fire Radiative Power (FRP) data. Analysis of variance revealed significant differences in PM concentrations between pre-fire, during-fire, and post-fire phases, with the proximal station (S1) showing the strongest response. Pearson correlations with False Discovery Rate adjustment demonstrated immediate associations between FRP and PM at S1 (r = 0.71-0.72, p < 0.05), while distal stations (S2-S4) exhibited significant correlations only after applying 1-2 day temporal lags (r = 0.44-0.49, p < 0.05), providing quantitative evidence of regional-scale pollutant transport. These findings establish an empirical foundation for developing early warning systems in fire-prone regions and underscore the necessity of considering temporal lags in air quality management strategies during wildfire events.