Classification of indoor-outdoor location using combined global positioning system (GPS) and temperature data for personal exposure assessment

OBJECTIVES The objectives of this study was to determine the accuracy of indoor-outdoor classification based on GPS and temperature data in three different seasons. METHODS In 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. RESULTS Determination 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. CONCLUSION The results showed that combining GPS and temperature data improved the accuracy of indoor-outdoor determination.