Spatiotemporal Variation in Ambient Particulate Metal Concentrations from Heavy Firework Activity in the Los Angeles Area Associated with the Independence Day Holiday: Initial Analysis of Filter Samples and ASCENT Data

DANIEL B. CURTIS, Zeinab Khalil, Tyler Deflin, Haroula D. Baliaka, Ryan Ward, John Seinfeld, Richard Flagan, Bradley Ries, Yumeng Cui, Roya Bahreini, Eleanor Bentley, Lelia Hawkins, Nga Lee Ng, Ann M. Dillner, Armistead G. Russell, California State University, Fullerton

     Abstract Number: 532
     Working Group: Urban Aerosols

Abstract
The July 4 Independence Day holiday is one of the worst air quality days of the year in the greater Los Angeles region due to extreme, albeit short-lived, particulate emissions from public and private use of fireworks, potentially impacting public health. Fireworks aerosol particles are especially concerning because they are known to contain certain heavy metals used as colorants or oxidants. To better understand the spatiotemporal variation in metal concentrations, ambient particulate samples were collected in the time period around July 4, 2024 at Fullerton and Downey, California. Filter samples were collected using portable samplers (AST UPAS v2+) and subsequently digested and analyzed in the laboratory using ICP-Optical Emission Spectroscopy (Agilent 4800). Metal concentrations (Xact EDXRF, SailBri Cooper, Inc.) from the ASCENT (the Atmospheric Science and Chemistry mEasurement NeTwork) sites located in Pico Rivera, Rubidoux, and Joshua Tree National Park were also analyzed. There was generally good agreement in metal concentrations from the filter samples and ASCENT data. Large increases in ambient concentrations were observed for known fireworks tracers, such as barium, strontium, aluminum, and copper for both the filter and ASCENT measurements. Additionally, increases in concentrations of potentially harmful metals such as chromium, lead, and arsenic were small but measurable. The filter samples indicated relatively high concentrations of zinc and calcium, while the ASCENT site at Pico Rivera did not. Potential reasons for discrepancies, such as freeway emissions, will be discussed. Preliminary analysis of the ASCENT data from the three sites indicates that the particle plume from the Los Angeles Basin may have been transported to the Rubidoux and Joshua Tree National Park sites, located approximately 80 km and 180 km east of downtown Los Angeles, respectively.