PROBING THE SOURCES OF METALS IN PARTICULATE MATTER: FIREWORKS AND FREEWAYS

Chronic and acute exposure to particulate matter has been linked to an increased risk of many adverse health effects, and the composition of the particulate matter is what deems it toxic or harmful. Vehicle emissions are consistent sources of particulate matter while fireworks are a transient source, but both sources are known to emit metals in particulate matter. Heavy metal air pollutants emitted from both sources include chromium and lead which are known for their carcinogenicity and toxicity. This study investigated air quality during July 4th, 2020, and 2021 in Fullerton, California by monitoring particle concentration and quantifying metals in total suspended particulate matter (TSP) and in particles with diameters less than 2.5 micrometers (PM2.5), which are especially important because they can penetrate deeply into human lungs. 2020 results show that chromium and lead displayed larger concentrations than the Federal Environmental Protection Agency (EPA) limits during Independence Day fireworks. 2021 results show that the air quality on July 5th was worse than the air quality on July 4th in terms of PM2.5 concentrations and exceeded the EPA limit for PM2.5. Metals in TSP quantified in 2021 showed conflicting results, where copper showed peak concentrations of 1500 ng/m3 on the evening of July 4th, while chromium and lead did not have peak concentrations occur until the afternoon on July 5th at 726 ng/m3 and 687 ng/m3, respectively. This study also quantified and compared ambient metals in TSP and PM2.5 in the near-road environment from a site adjacent to the 57-freeway in Fullerton, CA. A large variation in chromium and lead concentrations were observed in both particle sizes. For chromium, most of the mass was in PM2.5 which may negatively impact human health. However, for lead, on some sampling days a large portion of the mass was in TSP, which may indicate that lead is found in resuspended road dust rather than tailpipe emissions from vehicles