Within the context of a panel study of children with asthma in Montreal, Canada, we describe an automated classification of GPS data into location-based categories that makes use of temperature data to assist in discriminating indoor from outdoor locations. We compare our automated classification to time-activity diaries completed by the children. In addition, we compare continuous personal concentrations to fine particles (particulates with aerodynamic diameters 2.5 microns or less, PM2.5) assigned using both the time-activity diary and the automated GPS microenvironment data.