title: Effects of instrument precision and spatial variability on the assessment of the temporal variation of ambient air pollution in Atlanta, Georgia.
abstract: Data from the U.S. Environmental Protection Agency Air Quality System, the Southeastern Aerosol Research and Characterization database, and the Assessment of Spatial Aerosol Composition in Atlanta database for 1999 through 2002 have been used to characterize error associated with instrument precision and spatial variability on the assessment of the temporal variation of ambient air pollution in Atlanta, GA. These data are being used in time series epidemiologic studies in which associations of acute respiratory and cardiovascular health outcomes and daily ambient air pollutant levels are assessed. Modified semivariograms are used to quantify the effects of instrument precision and spatial variability on the assessment of daily metrics of ambient gaseous pollutants (SO2, CO, NOx, and O3) and fine particulate matter ([PM2.5] PM2.5 mass, sulfate, nitrate, ammonium, elemental carbon [EC], and organic carbon [OC]). Variation because of instrument imprecision represented 7-40% of the temporal variation in the daily pollutant measures and was largest for the PM2.5 EC and OC. Spatial variability was greatest for primary pollutants (SO2, CO, NOx, and EC). Population-weighted variation in daily ambient air pollutant levels because of both instrument imprecision and spatial variability ranged from 20% of the temporal variation for O3 to 70% of the temporal variation for SO2 and EC. Wind
authors.affiliation: School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0512, USA.
authors.forename: Katherine S
authors.initials: KS
authors.lastname: Wade
authors.forename: James A
authors.initials: JA
authors.lastname: Mulholland
authors.forename: Amit
authors.initials: A
authors.lastname: Marmur
authors.forename: Armistead G
authors.initials: AG
authors.lastname: Russell
authors.forename: Ben
authors.initials: B
authors.lastname: Hartsell
authors.forename: Eric
authors.initials: E
authors.lastname: Edgerton
authors.forename: Mitch
authors.initials: M
authors.lastname: Klein
authors.forename: Lance
authors.initials: L
authors.lastname: Waller
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Peel
authors.forename: Paige E
authors.initials: PE
authors.lastname: Tolbert
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000032:analysis; D002248:Carbon Monoxide / Q000032:analysis; D002947:Cities; D004391:Dust / Q000032:analysis; D004784:Environmental Monitoring / Q000295:instrumentation*; D005845:Georgia; D009589:Nitrogen Oxides / Q000032:analysis; D010126:Ozone / Q000032:analysis; D015203:Reproducibility of Results; D013458:Sulfur Dioxide / Q000032:analysis; D013997:Time Factors; D035501:Uncertainty; D014919:Wind
chemical_list: D000393:Air Pollutants; D004391:Dust; D009589:Nitrogen Oxides; D013458:Sulfur Dioxide; D010126:Ozone; D002248:Carbon Monoxide