TY - JOUR
T1 - Chemical composition and redox activity of PM0.25 near Los Angeles International Airport and comparisons to an urban traffic site
AU - Shirmohammadi, Farimah
AU - Lovett, Christopher
AU - Sowlat, Mohammad Hossein
AU - Mousavi, Amirhosein
AU - Verma, Vishal
AU - Shafer, Martin M.
AU - Schauer, James J.
AU - Sioutas, Constantinos
N1 - Funding Information:
The present project was supported by grant numbers 1R21AG050201-01A1 and 1RF1AG051521-01 from the U.S. National Institutes of Health (NIH). The authors wish to thank the staff of the Wisconsin State Laboratory of Hygiene (WSLH) for their assistance with the chemical analysis. We also acknowledge the support of University of Southern California Provost PhD fellowship. Appendix A
Publisher Copyright:
© 2017 Elsevier B.V.
PY - 2018/1/1
Y1 - 2018/1/1
N2 - To investigate the relative impacts of emissions from Los Angeles International Airport (LAX), as well as the impacts of traffic emissions from freeways, on the oxidative potential of particulate matter (PM), PM0.25 were collected at two urban background locations in Los Angeles. Redox activity of the PM samples was measured by means of an in vitro alveolar macrophage assay that quantifies the formation of reactive oxygen species (ROS) in cells, and detailed chemical analyses were performed to determine the speciated chemical composition of collected PM. A molecular marker-based chemical mass balance (MM-CMB) model was applied to estimate the relative contributions from the following primary sources to the organic carbon (OC) component of PM: mobile sources (combined gasoline and diesel vehicles), wood smoke, vegetative detritus, road dust and ship emissions. A source profile of aircraft emissions was not included in the model; however its contribution was estimated from un-apportioned primary OC in the MM-CMB model (“other OC”) after accounting for the contribution of secondary organic carbon (SOC) to OC. The contribution of mobile sources to OC was 82% and 28% at the central Los Angeles site (freeway emissions) and the LAX site, respectively. The estimated contribution of aircraft emissions to PM0.25 OC was 36% at the LAX site. ROS activity levels showed little spatial variability, with no statistically significant difference between the averages observed at LAX (24.75 ± 4.01 μg Zymosan/m3) and central Los Angeles (27.77 ± 2 0.32 μg Zymosan/m3), suggesting similar levels of inhalation exposure to redox active species of PM0.25. A multiple linear regression analysis indicated that the variability in ROS activity is best explained by the chemical markers of major identified sources: EC emitted by traffic, and sulfur, considered in our study as a potential tracer of aircraft emissions, with statistically significantly higher concentrations of sulfur at the LAX site (p < 0.001).
AB - To investigate the relative impacts of emissions from Los Angeles International Airport (LAX), as well as the impacts of traffic emissions from freeways, on the oxidative potential of particulate matter (PM), PM0.25 were collected at two urban background locations in Los Angeles. Redox activity of the PM samples was measured by means of an in vitro alveolar macrophage assay that quantifies the formation of reactive oxygen species (ROS) in cells, and detailed chemical analyses were performed to determine the speciated chemical composition of collected PM. A molecular marker-based chemical mass balance (MM-CMB) model was applied to estimate the relative contributions from the following primary sources to the organic carbon (OC) component of PM: mobile sources (combined gasoline and diesel vehicles), wood smoke, vegetative detritus, road dust and ship emissions. A source profile of aircraft emissions was not included in the model; however its contribution was estimated from un-apportioned primary OC in the MM-CMB model (“other OC”) after accounting for the contribution of secondary organic carbon (SOC) to OC. The contribution of mobile sources to OC was 82% and 28% at the central Los Angeles site (freeway emissions) and the LAX site, respectively. The estimated contribution of aircraft emissions to PM0.25 OC was 36% at the LAX site. ROS activity levels showed little spatial variability, with no statistically significant difference between the averages observed at LAX (24.75 ± 4.01 μg Zymosan/m3) and central Los Angeles (27.77 ± 2 0.32 μg Zymosan/m3), suggesting similar levels of inhalation exposure to redox active species of PM0.25. A multiple linear regression analysis indicated that the variability in ROS activity is best explained by the chemical markers of major identified sources: EC emitted by traffic, and sulfur, considered in our study as a potential tracer of aircraft emissions, with statistically significantly higher concentrations of sulfur at the LAX site (p < 0.001).
KW - Aircraft emissions
KW - Oxidative potential
KW - PM
KW - Ultrafine particles
KW - Vehicle exhaust emissions
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U2 - 10.1016/j.scitotenv.2017.08.239
DO - 10.1016/j.scitotenv.2017.08.239
M3 - Article
C2 - 28873663
AN - SCOPUS:85028369874
SN - 0048-9697
VL - 610-611
SP - 1336
EP - 1346
JO - Science of the Total Environment
JF - Science of the Total Environment
ER -