Wildfire-Related Long-term Air Quality Effects in Los Angeles, USA

This thesis aims to study the long-term impact of fires on air quality in the Los Angeles area between 2005 and 2025. The research focuses on nitrogen dioxide (NO₂) and particulate matter (PM), which are key pollution indicators with significant health and environmental impacts. Data were collected using satellite and ground-based measurements, specifically from the Aura satellite's Ozone Monitoring Instrument (OMI) and from United States Environmental Protection Agency (EPA) stations via the Air Quality System (AQS) and AirData systems. Time series were created from the data to identify seasonal variations, long-term trends, and significant deviations related to fire events. The results revealed a consistent downward trend in the concentrations of NO₂ and PM₂.₅ and PM₁₀ particles. This is primarily attributed to the implementation of environmental policies, advancements in vehicle technology, and a gradual reduction in industrial emissions. However, sharp increases in pollutant concentrations were observed during periods of extensive fires, which in some cases lasted several days and affected areas beyond the city limits. To investigate these episodes, satellite maps of tropospheric NO₂ were created. These maps revealed spatial variations in emissions and helped identify areas with the highest pollution levels. Comparing satellite and ground-based data showed a moderate positive correlation, varying depending on the geographical location of the station, fire intensity, and prevailing meteorological conditions. These findings emphasize the importance of combining different types of measurement to provide a more comprehensive assessment of air quality and a better understanding of the effects of fires. The research also highlights the need for continuous monitoring and the reinforcement of preventive measures, given that fires are becoming more frequent and intense due to climate change. Comprehensive data analysis is crucial for developing policies that protect the atmosphere and public health, and for promoting more sustainable and resilient environmental management in the Los Angeles area in the future.