Tracking the Impact of Wildfire on Urban Air Pollution: A Satellite-Based Assessment of 2025 Los Angeles Wildfire

Wildfires are increasingly altering atmospheric composition across urban regions, with Southern California being a critical hotspot due to its frequent fire activity and population density. This study evaluates the impact of the January 2025 wildfires on urban air quality in the Los Angeles metropolitan area using satellite-derived observations of ozone (O₃), nitrogen dioxide (NO₂), carbon monoxide (CO), and aerosol optical depth (AOD). We employed data from TROPOMI and MODIS sensors to capture the spatiotemporal evolution of these pollutants across three phases: pre-fire (December 22, 2024–January 5, 2025), active fire (January 6–30), and post-fire (January 31–February 10). Results revealed marked increases in pollutant levels during the wildfire period, with CO exhibiting the most substantial rise (14% on average, with peaks exceeding 300% of the baseline), fol-lowed by NO₂ (33%) and AOD (28.6%). O₃ exhibited a modest enhancement (~4%), likely constrained by limited wintertime photochemistry and ozone titration by freshly emitted NO. This research helps us better understand how wildfire smoke affects air quality over time and shows how satellite tools can improve pollution monitoring in cities that are at high risk of wildfires due to growing populations and changing climate.