title: Assessment of heterogeneity of metal composition of fine particulate matter collected from eight U.S. counties using principal component analysis.
abstract: The main objectives of this study are to (1) characterize chemical constituents of particulate matter (PM) and (2) compare overall differences in PM collected from eight US. counties. This project was undertaken as a part of a larger research program conducted by the Johns Hopkins Particulate Matter Research Center (JHPMRC). The goal of the JHPMRC is to explore the relationship between health effects and exposure to ambient PM of differing composition. The JHPMRC collected weekly filter-based ambient fine particle samples from eight US. counties between January 2008 and January 2010. Each sampling effort consisted of a 5-6-week sampling period. Filters were analyzed for 25 metals using inductively coupled plasma mass spectrometry (ICP-MS). Overall compositional differences were ranked by principal component analysis (PCA). The results showed that weekly concentrations of each element varied 3-40 times between the eight counties. PCA showed that the first five principal components explained 85% of the total variance. The authors found significant overall compositional differences in PM as the average of standardized principal component scores differed between the counties. These findings demonstrate PCA is a useful tool to identify the differences in PM compositional mixtures by county. These differences will be helpful for epidemiological and toxicological studies to help explain why health risks associated with PM exposure are different in locations with similar mass concentrations of PM.
authors.affiliation: Department of Environmental Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
authors.forename: Inkyu
authors.initials: I
authors.lastname: Han
authors.forename: Jana N
authors.initials: JN
authors.lastname: Mihalic
authors.forename: Juan P
authors.initials: JP
authors.lastname: Ramos-Bonilla
authors.forename: Ana M
authors.initials: AM
authors.lastname: Rule
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Polyak
authors.forename: Roger D
authors.initials: RD
authors.lastname: Peng
authors.forename: Alison S
authors.initials: AS
authors.lastname: Geyh
authors.forename: Patrick N
authors.initials: PN
authors.lastname: Breysse
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000465:Algorithms; D004784:Environmental Monitoring; D013058:Mass Spectrometry; D008670:Metals / Q000032:analysis*; D052638:Particulate Matter / Q000032:analysis*; D025341:Principal Component Analysis; D013048:Specimen Handling; D014481:United States
chemical_list: D000393:Air Pollutants; D008670:Metals; D052638:Particulate Matter