Abstract
ObjectivesThe objectives of this study was to determine the accuracy of indoor-outdoor classification based on GPS and temperature data in three different seasons.MethodsIn the present study, a global positioning system (GPS) was used alongside temperature data collected in the field by a technician who visited 53 different indoor locations during summer, autumn and winter. The indoor-outdoor location was determined by GPS data alone, and in combination with temperature data.ResultsDetermination of location by the GPS signal alone, based on the loss of GPS signal and using the used number of satellites (NSAT) signal factor, simple percentage agreements of 73.6 ± 2.9%, 72.9 ± 3.4%, and 72.1 ± 3.1% were obtained for summer, autumn, and winter, respectively. However, when temperature and GPS data were combined, simple percentage agreements were significantly improved (87.9 ± 3.3%, 84.1 ± 2.8%, and 86.3 ± 3.1%, respectively). A temperature criterion for indoor-outdoor determination of ~ Δ 2°C for 2 min could be applied during all three seasons.ConclusionThe results showed that combining GPS and temperature data improved the accuracy of indoor-outdoor determination.
Highlights
Personal exposure is a factor of both the concentration in the microenvironment, and the duration of the exposure period
Material and methods A field technician used a global positioning system (GPS) signal receiver (GPS 742, Ascen Industry, Korea) and a temperature data logger (UX-100-003, Onset Computer Corporation, Cape Cod, MA, USA) to record data while visiting 53 types of indoor locations that were selected based on the time activity patterns of 2358 individuals in Seoul, Korea [14]
There were no significant differences in calculated simple percentage agreements and Kappa coefficients among three seasons
Summary
Personal exposure is a factor of both the concentration in the microenvironment, and the duration of the exposure period. Several traditional methods have been used for collecting time-location information, including questionnaires, observations, recall interviews and time-activity diaries (TAD) recorded by study participants [3,4,5,6]. The use of a portable global positioning system (GPS) signal receivers has been used to track personal time-location and traveling pattern data, both with and without corresponding manually written TAD [7,8,9]. This technique offers many advantages over traditional methods, including near-continuous location tracking, high temporal resolution, and minimum reporting burden for participants [10]. GPS devices are subject to errors caused by satellite or receiver issues, atmospheric and ionospheric disturbances, multipath signal reflection, and signal loss or
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