Chemical, Physical, and Optical Properties of Ambient Particulate Matter during Widespread Fireworks Use in Southern California
DANIEL B. CURTIS, Danielle Rocco, Esther Morales, Jason Truong, Tyler Deflin,
California State University, Fullerton Abstract Number: 513
Working Group: Urban Aerosols
AbstractChronic and acute exposure to particulate matter has been linked to an increased risk of adverse health effects in humans. Within the Los Angeles basin, one of the worst annual air quality days is the July 4 holiday, when sanctioned and personal use of fireworks is prevalent and PM
2.5 concentrations approach 300 μg m
-3. Fireworks emissions are especially concerning because the particles contain potentially harmful metals that are used in salts to produce the varied colors seen during fireworks explosions.
This study investigated air quality during July 4th, 2020, and 2021 in Fullerton, California, located in the Los Angeles metropolitan area. Ambient concentrations of the selected metals barium, chromium, copper, lead, and strontium were measured by collecting particles on filters, extracting, then analyzing with atomic absorption spectroscopy. In 2021, barium, copper, and strontium peaked on the night of July 4-5, with concentrations of 1761 ng m
-3, 1472 ng m
-3, and 668 ng m
-3, respectively. Chromium and lead concentrations varied, indicating that they may be controlled by factors other than fireworks in this location.
Submicrometer particle size distributions were measured using a Scanning Mobility Particle Sizer (TSI, Inc.) and aerosol optical properties were measured using a Cavity Attenuated Phase Shift Spectrometer (PM
ex, Aerodyne) at a wavelength of 450 nm and an Integrating Nephelometer (2-WIN, Ambilabs) at wavelengths of 450 nm and 525 nm. In addition, two PurpleAir sensors (one outdoor and one indoor) were deployed and compared. The real and imaginary refractive indices of the aerosol were retrieved using Mie theory and were variable, with an effective real refractive index of approximately 1.75 and an effective imaginary refractive index of 0.05 at a wavelength of 450 nm, indicating that the particles were slightly absorbing.