Time-Location Analysis for Exposure Assessment Studies of Children Using a Novel Global Positioning System Instrument. (Children's Health / Articles)

By Elgethun, Kai; Fenske, Richard A. et al. | Environmental Health Perspectives, January 2003 | Go to article overview
Save to active project

Time-Location Analysis for Exposure Assessment Studies of Children Using a Novel Global Positioning System Instrument. (Children's Health / Articles)


Elgethun, Kai, Fenske, Richard A., Yost, Michael G., Palcisko, Gary J., Environmental Health Perspectives


Global positioning system (GPS) technology is used widely for business and leisure activities and offers promise for human time-location studies to evaluate potential exposure to environmental contaminants. In this article we describe the development of a novel GPS instrument suitable for tracking the movements of young children. Eleven children in the Seattle area (2-8 years old) wore custom-designed data-logging GPS units integrated into clothing. Location data were transferred into geographic information systems software for map overlay, visualization, and tabular analysis. Data were grouped into five location categories (in vehicle, inside house, inside school, inside business, and outside) to determine time spent and percentage reception in each location. Additional experiments focused on spatial resolution, reception efficiency in typical environments, and sources of signal interference. Significant signal interference occurred only inside concrete/steel-frame buildings and inside a power substation. The GPS instruments provided adequate spatial resolution (typically about 2-3 m outdoors and 4-5 m indoors) to locate subjects within distinct microenvironments and distinguish a variety of human activities. Reception experiments showed that location could be tracked outside, proximal to buildings, and inside some buildings. Specific location information could identify movement in a single room inside a home, on a playground, or along a fence line. The instrument, worn in a vest or in bib overalls, was accepted by children and parents. Durability of the wiring was improved early in the study to correct breakage problems. The use of GPS technology offers a new level of accuracy for direct quantification of time-location activity patterns in exposure assessment studies. Key words: activity pattern, behavior, children, exposure assessment, GIS, GPS, organophosphorous pesticides, time-location, tracking. Environ Health Perspect 111:115-122 (2003). [Online 11 December 2002]

doi: 10.1289/ehp.5350 available via http://dx.doi.org/

**********

Evaluation of children's exposure to environmental health hazards is essential for both epidemiology and risk assessment and has become a recent focus of national concern (1). An essential component of exposure assessment is knowledge of where individuals spend their time. Such time-location information can be linked with pollutant concentration data to produce exposure estimates for well-defined environments, often called microenvironments (2). Conventional time-location analysis has relied on interviews or diaries (3-6). Efforts have been made recently to improve the validity of these methods, including the "shadowing" of subjects with an observer, and use of a beeper to prompt subjects to record time-location data (7,8). Other methods and technologies have been explored but have not proven practical for human exposure studies (9,10). The purpose of the study reported in this article was to identify and test a new method for tracking preschool children throughout the course of a day.

The location of children has most often been documented through parental interviews and diaries (11-13). Although probably adequate for gross location analysis (home/not home), they are not considered reliable for more detailed characterizations (time indoors or outdoors at home or day care, time in vehicle). Evaluation of children's microactivities (e.g., hand-to-mouth behavior) has used videotaping at single locations (14,15), but this approach cannot be applied realistically to track children's locations throughout the day.

Global positioning system technology. The essential aspects of global positioning system (GPS) technology have been described in a report by the U.S. Environmental Protection Agency (16). A summary of how GPS units collect temporal and locational data is provided here. GPS satellites orbit the earth twice every 24 hr transmitting a 50-W signal at 1,575.

The rest of this article is only available to active members of Questia

Sign up now for a free, 1-day trial and receive full access to:

  • Questia's entire collection
  • Automatic bibliography creation
  • More helpful research tools like notes, citations, and highlights
  • Ad-free environment

Already a member? Log in now.

Notes for this article

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
Loading One moment ...
Project items
Notes
Cite this article

Cited article

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

Cited article

Time-Location Analysis for Exposure Assessment Studies of Children Using a Novel Global Positioning System Instrument. (Children's Health / Articles)
Settings

Settings

Typeface
Text size Smaller Larger
Search within

Search within this article

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

While we understand printed pages are helpful to our users, this limitation is necessary to help protect our publishers' copyrighted material and prevent its unlawful distribution. We are sorry for any inconvenience.
Full screen

matching results for page

Cited passage

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

Cited passage

Welcome to the new Questia Reader

The Questia Reader has been updated to provide you with an even better online reading experience.  It is now 100% Responsive, which means you can read our books and articles on any sized device you wish.  All of your favorite tools like notes, highlights, and citations are still here, but the way you select text has been updated to be easier to use, especially on touchscreen devices.  Here's how:

1. Click or tap the first word you want to select.
2. Click or tap the last word you want to select.

OK, got it!

Thanks for trying Questia!

Please continue trying out our research tools, but please note, full functionality is available only to our active members.

Your work will be lost once you leave this Web page.

For full access in an ad-free environment, sign up now for a FREE, 1-day trial.

Already a member? Log in now.

Are you sure you want to delete this highlight?