Using Global Positioning Systems (GPS) and temperature data to generate time-activity classifications for estimating personal exposure in air monitoring studies: an automated method.
Environ Health. 2014;13(1):33
Publication Type
Elizabeth Nethery
Gary Mallach
Daniel Rainham
Mark S Goldberg
Amanda J Wheeler
Author Affiliation
Water and Air Quality Bureau, HECSB, Health Canada, 269 Laurier Avenue West, AL 4903C, Ottawa, Ontario K1A 0 K9, Canada.
Environ Health. 2014;13(1):33
Publication Type
Air Pollutants - analysis
Environmental Monitoring - methods
Geographic Information Systems
Particulate Matter - analysis
Time Factors
Personal exposure studies of air pollution generally use self-reported diaries to capture individuals' time-activity data. Enhancements in the accuracy, size, memory and battery life of personal Global Positioning Systems (GPS) units have allowed for higher resolution tracking of study participants' locations. Improved time-activity classifications combined with personal continuous air pollution sampling can improve assessments of location-related air pollution exposures for health studies.
Data was collected using a GPS and personal temperature from 54 children with asthma living in Montreal, Canada, who participated in a 10-day personal air pollution exposure study. A method was developed that incorporated personal temperature data and then matched a participant's position against available spatial data (i.e., road networks) to generate time-activity categories. The diary-based and GPS-generated time-activity categories were compared and combined with continuous personal PM2.5 data to assess the impact of exposure misclassification when using diary-based methods.
There was good agreement between the automated method and the diary method; however, the automated method (means: outdoors?=?5.1%, indoors other =9.8%) estimated less time spent in some locations compared to the diary method (outdoors?=?6.7%, indoors other?=?14.4%). Agreement statistics (AC1?=?0.778) suggest 'good' agreement between methods over all location categories. However, location categories (Outdoors and Transit) where less time is spent show greater disagreement: e.g., mean time "Indoors Other" using the time-activity diary was 14.4% compared to 9.8% using the automated method. While mean daily time "In Transit" was relatively consistent between the methods, the mean daily exposure to PM2.5 while "In Transit" was 15.9 µg/m3 using the automated method compared to 6.8 µg/m3 using the daily diary.
Mean times spent in different locations as categorized by a GPS-based method were comparable to those from a time-activity diary, but there were differences in estimates of exposure to PM2.5 from the two methods. An automated GPS-based time-activity method will reduce participant burden, potentially providing more accurate and unbiased assessments of location. Combined with continuous air measurements, the higher resolution GPS data could present a different and more accurate picture of personal exposures to air pollution.
Cites: J Expo Sci Environ Epidemiol. 2014 May-Jun;24(3):260-823632991
Cites: Health Place. 2012 Jan;18(1):55-6221945085
Cites: Med Sci Sports Exerc. 2011 Feb;43(2):365-7220581721
Cites: Int J Health Geogr. 2011;10:6422142322
Cites: Environ Health. 2011;10:10122082316
Cites: J Environ Monit. 2009 Jul;11(7):1331-920449221
Cites: Accid Anal Prev. 2010 Mar;42(2):523-920159076
Cites: Int J Health Geogr. 2009;8:6819948034
Cites: Sci Total Environ. 2009 Sep 1;407(18):5184-9319577794
Cites: J Expo Sci Environ Epidemiol. 2009 Mar;19(3):317-2418478047
Cites: Int J Health Geogr. 2008;7:5919032783
Cites: Br J Math Stat Psychol. 2008 May;61(Pt 1):29-4818482474
Cites: J Expo Sci Environ Epidemiol. 2007 Sep;17(6):549-5817505504
Cites: Environ Sci Technol. 2007 Apr 1;41(7):2422-817438795
Cites: J Expo Sci Environ Epidemiol. 2007 Mar;17(2):196-20616773123
Cites: J Expo Sci Environ Epidemiol. 2006 May;16(3):264-7416617313
Cites: Environ Sci Technol. 2005 Jul 15;39(14):5105-1216082937
Cites: J Toxicol Environ Health A. 2005 Jul 9-23;68(13-14):1243-6116024500
Cites: Epidemiology. 2005 May;16(3):396-40515824557
Cites: J Air Waste Manag Assoc. 2004 Sep;54(9):1197-21115468672
Cites: J Expo Anal Environ Epidemiol. 2001 May-Jun;11(3):207-1511477518
Cites: J Air Waste Manag Assoc. 2000 Jul;50(7):1125-3210939206
Cites: Environ Health. 2013;12(1):8624107241
Cites: Am J Prev Med. 2013 Jan;44(1):85-823253655
Cites: Sci Total Environ. 2013 Jan 15;443:184-9323183229
Cites: Environ Pollut. 2013 May;176:92-923416743
Cites: J Environ Monit. 2012 Aug;14(8):2270-422739933
Cites: Am J Prev Med. 2012 May;42(5):e87-9622516507
PubMed ID
24885722 View in PubMed
Less detail