Using Global Positioning Systems (GPS) and temperature data to generate time-activity classifications for estimating personal exposure in air monitoring studies: an automated method

Table 1 Step-wise approach for the spatial classification of GPS points

What temperature zone is used?	Criteria for assigning points spatially compared to the base geospatial data (buildings, roads)? (in order)	What activity classification is assigned?
None. This occurs before zones are considered (all points that fit the criteria are assigned)	Points with speed from the GPS >5 km/hr and within 20 m of a road segment	In Transit
Flat zone¹ (temperature is relatively constant)	Points with GPS speed < 5 km/hr and within 25 m of road segment	In Transit
	Points within 25 m of subjects’ home	Home
	Points within 5 m of subjects’ school	School
	Points within 15 m of any other building	Indoors Other
	Points remaining (unclassified)	Outdoors
Transition zone (temperature is changing)	Points with GPS speed < 5 km/hr and within 5 m of road segment	In Transit
	Points within 5 m of subjects’ home	Home
	Points within 5 m of subjects’ school	School
	Points within 2 m of any other building	Indoors Other
	Points remaining (unclassified)	Outdoors

¹Within flat zones, a spatial criterion was applied for all points in the zone, using only the location of the center (obtained using the “mean centers tool” in ArcGIS) point in the cluster.

ISSN: 1476-069X