Fig. 2

Graphical flow chart of home identification of the time-activity model. (a) Map of the raw GPS data (blue) collected from a representative participant carrying a personal air quality monitor over a week. (b) 3D density plot of participant’s time budget projected on a map. “Home” location has the highest point density (i.e. most time spent). (c) A spatial elliptical zone created with a rule-based model to identify “home” that included indoor (red) and outdoor (blue) micro-environments (separated in Step 4). The spread distances (\(\delta\)Lon and \(\delta\)Lat) around the centroid are often larger than the GIS footprints of the buildings (grey) and depend on multiple factors. Map data from Google Maps 2021 (a and b) and OpenStreetMap(c)