Nethery, E and Mallach, G and Rainham, D and Goldberg, MS and Wheeler, AJ, Using Global Positioning Systems (GPS) and temperature data to generate time-activity classifications for estimating personal exposure in air monitoring studies: an automated method, Environmental Health, 13 Article 33. ISSN 1476-069X (2014) [Refereed Article]
Licensed under Creative Commons Attribution 2.0 Generic (CC BY 2.0) http://creativecommons.org/licenses/by/2.0/
METHODS: 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.
RESULTS: 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.
CONCLUSIONS: 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.
|Item Type:||Refereed Article|
|Keywords:||Time activity diary, Particulate air pollution, Global Positioning Systems (GPS), Personal exposure|
|Research Division:||Medical and Health Sciences|
|Research Group:||Public Health and Health Services|
|Research Field:||Environmental and Occupational Health and Safety|
|Objective Group:||Public Health (excl. Specific Population Health)|
|Objective Field:||Environmental Health|
|Author:||Wheeler, AJ (Dr Amanda Wheeler)|
|Web of Science® Times Cited:||14|
|Deposited By:||Menzies Institute for Medical Research|
|Downloads:||315 View Download Statistics|
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