title: GPS-based microenvironment tracker (MicroTrac) model to estimate time-location of individuals for air pollution exposure assessments: model evaluation in central North Carolina.
abstract: A critical aspect of air pollution exposure assessment is the estimation of the time spent by individuals in various microenvironments (ME). Accounting for the time spent in different ME with different pollutant concentrations can reduce exposure misclassifications, while failure to do so can add uncertainty and bias to risk estimates. In this study, a classification model, called MicroTrac, was developed to estimate time of day and duration spent in eight ME (indoors and outdoors at home, work, school; inside vehicles; other locations) from global positioning system (GPS) data and geocoded building boundaries. Based on a panel study, MicroTrac estimates were compared with 24-h diary data from nine participants, with corresponding GPS data and building boundaries of home, school, and work. MicroTrac correctly classified the ME for 99.5% of the daily time spent by the participants. The capability of MicroTrac could help to reduce the time-location uncertainty in air pollution exposure models and exposure metrics for individuals in health studies.
authors.affiliation: National Exposure Research Laboratory, US EPA, Research Triangle Park, NC, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Breen
authors.affiliation: National Center for Environmental Assessment, US EPA, Research Triangle Park, NC, USA.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Long
authors.affiliation: National Exposure Research Laboratory, US EPA, Research Triangle Park, NC, USA.
authors.forename: Bradley D
authors.initials: BD
authors.lastname: Schultz
authors.affiliation: National Health and Environmental Effects Research Laboratory, US EPA, Research Triangle Park, NC, USA.
authors.forename: James
authors.initials: J
authors.lastname: Crooks
authors.affiliation: National Health and Environmental Effects Research Laboratory, US EPA, Research Triangle Park, NC, USA.
authors.forename: Miyuki
authors.initials: M
authors.lastname: Breen
authors.affiliation: Office of Air Quality Planning and Standards, US EPA, Research Triangle Park, NC, USA.
authors.forename: John E
authors.initials: JE
authors.lastname: Langstaff
authors.affiliation: National Exposure Research Laboratory, US EPA, Research Triangle Park, NC, USA.
authors.forename: Kristin K
authors.initials: KK
authors.lastname: Isaacs
authors.affiliation: National Exposure Research Laboratory, US EPA, Research Triangle Park, NC, USA.
authors.forename: Yu-Mei
authors.initials: YM
authors.lastname: Tan
authors.affiliation: National Exposure Research Laboratory, US EPA, Research Triangle Park, NC, USA.
authors.forename: Ronald W
authors.initials: RW
authors.lastname: Williams
authors.affiliation: National Center for Environmental Assessment, US EPA, Research Triangle Park, NC, USA.
authors.forename: Ye
authors.initials: Y
authors.lastname: Cao
authors.affiliation: Immediate Office of the Assistant Administrator, US EPA, Research Triangle Park, NC, USA.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Geller
authors.affiliation: National Health and Environmental Effects Research Laboratory, US EPA, Research Triangle Park, NC, USA.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Devlin
authors.affiliation: Environmental Health Sciences, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Stuart A
authors.initials: SA
authors.lastname: Batterman
authors.affiliation: National Exposure Research Laboratory, US EPA, Research Triangle Park, NC, USA.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Buckley
mesh_terms: D000393:Air Pollutants / Q000633:toxicity*; D000465:Algorithms; D004781:Environmental Exposure; D040362:Geographic Information Systems; D008962:Models, Theoretical; D009657:North Carolina; D035501:Uncertainty
chemical_list: D000393:Air Pollutants