QUANTIFICATION OF AMBIENT PARTICULATE METAL CONCENTRATIONS DURING EXTREME AIR POLLUTION EVENTS DUE TO FIREWORKS USE DURING THE INDEPENDENCE DAY HOLIDAY IN SOUTHERN CALIFORNIA

Exposure to particulate matter in ambient air is correlated with various negative health impacts in humans. Particulate matter with a diameter less than 2.5 micrometers (PM2.5) is especially harmful to the respiratory system due to deep penetration and the ability for particles to enter the bloodstream, carrying any potential harmful compounds throughout the body. Exposure to metals, such as arsenic, lead, and chromium, is linked with various negative health effects. A major source of metal-containing PM2.5 is firework activity because metal salts are used as colorants and oxidants. In the Los Angeles area, July 4 is one of the worst air quality days of the year due to widespread firework use, exposing the population to inhalation of potentially harmful metal concentrations. The aim of this study was to quantify the concentrations of metals in PM2.5 on and around the days of July 4, 2023 and July 4, 2024 at two suburban sites in Orange County, California. Filter samples were collected using a personal air samplers equipped with a PM2.5 inlet (Access Sensors Technology, UPAS v1 and v2+) on 37mm polytetrafluoroethylene (PTFE, Teflon) filters, extracted in nitric acid into solution, and quantified using inductively-coupled plasma – optical emission spectroscopy (ICP-OES, Agilent 5800). 22 elements were analyzed for potentially elevated concentrations to determine which could be attributed to firework activity. Results showed elevated concentrations for strontium and barium with several other metals that can be attributed to firework activity. Increased concentrations of other metals, such as iron and copper were also observed on July 4, but it is unclear if these increases were due solely to fireworks or due to other potential sources of background pollution, such as nearby roadways.