title: Spatiotemporal variability of tetrachloroethylene in residential indoor air due to vapor intrusion: a longitudinal, community-based study.
abstract: The migration of volatile contaminants from groundwater and soil into indoor air is a potential health threat at thousands of contaminated sites across the country. This phenomenon, known as vapor intrusion, is characterized by spatial and temporal heterogeneity. This study examined short-term fluctuations in concentrations of tetrachloroethylene (PCE) in the indoor air of residential homes due to vapor intrusion in a community in San Antonio, Texas, that sits atop an extensive, shallow plume of contaminated groundwater. Using a community-based design, we removed potential indoor sources of PCE and then collected twelve 3-day passive indoor air samples in each of the 20 homes. Results demonstrated a one-order-of-magnitude variability in concentration across both space and time among the study homes, although all measured concentrations were below risk-based screening levels. We found that within any given home, indoor concentrations increase with the magnitude of the barometric pressure drop (P=0.048) and humidity (P<0.001), while concentrations decrease as wind speed increases (P<0.001) and also during winter (P=0.001). In a second analysis to examine sources of spatial variability, we found that indoor air PCE concentrations between homes increase with groundwater concentration (P=0.030) and a slab-on-grade (as compared with a crawl space) foundation (P=0.028), whereas concentrations decrease in homes without air conditioners (P=0.015). This study offers insights into the drivers of temporal and spatial variability in vapor intrusion that can inform decisions regarding monitoring and exposure assessment at affected sites.
authors.affiliation: Department of Environmental Sciences & Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA.
authors.forename: Jill E
authors.initials: JE
authors.lastname: Johnston
authors.affiliation: Department of Environmental Sciences & Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA.
authors.forename: Jacqueline MacDonald
authors.initials: JM
authors.lastname: Gibson
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D016902:Air Pollution, Indoor / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods; D004785:Environmental Pollutants / Q000032:analysis*; D060587:Groundwater / Q000737:chemistry; D006798:Housing; D006801:Humans; D008137:Longitudinal Studies; D012044:Regression Analysis; D012111:Residence Characteristics; D062211:Spatio-Temporal Analysis; D013750:Tetrachloroethylene / Q000032:analysis*; D013781:Texas; D055548:Vapor Pressure; D014887:Weather
chemical_list: D000393:Air Pollutants; D004785:Environmental Pollutants; D013750:Tetrachloroethylene
references.citation: Environ Health Perspect. 1985 Oct;62:281-7
references.pmid: 4085431
references.citation: Environ Health. 2009 Sep 24;8:44
references.pmid: 19778411
references.citation: Environ Sci Technol. 2009 Feb 1;43(3):650-6
references.pmid: 19244997
references.citation: Occup Environ Med. 1997 Dec;54(12):848-53
references.pmid: 9470891
references.citation: Environ Health Perspect. 2012 Apr;120(4):616-21
references.pmid: 22142966
references.citation: J Air Waste Manage Assoc. 1990 Apr;40(4):498-506
references.pmid: 2340149
references.citation: Toxicol Ind Health. 2002 Mar;18(2):91-106
references.pmid: 12868798
references.citation: Indoor Air. 2010 Feb;20(1):85-90
references.pmid: 19874401
references.citation: Environ Sci Technol. 1994 May 1;28(5):898-902
references.pmid: 22191832
references.citation: Environ Sci Technol. 2011 Feb 1;45(3):1007-13
references.pmid: 21162557
references.citation: Health Phys. 1985 Mar;48(3):265-81
references.pmid: 3980214
references.citation: Environ Health Perspect. 2004 Dec;112(17):1691-6
references.pmid: 15579415
references.citation: J Expo Sci Environ Epidemiol. 2009 Nov;19(7):682-93
references.pmid: 19240761
references.citation: Health Phys. 1991 Feb;60(2):189-97
references.pmid: 1989940
references.citation: J Expo Anal Environ Epidemiol. 2004;14 Suppl 1:S4-S13
references.pmid: 15118740
references.citation: Environ Sci Technol. 2012 May 1;46(9):4792-9
references.pmid: 22486634