Table 2.

Summary of GIS-based source indicators

Source Category	Variables	Data Sources
Traffic Indicators	Un-weighted and kernel-weighted road and traffic density, number of signaled intersections, distance to and characteristics of nearest roadway	New York Metropolitan Transportation Council, Highway Performance Monitoring System, Accident Location Information System, Market Planning Solutions TrafficMetrix data, NYC Department of Transportation Truck Routes
Population Metrics	Census population density, LandScan population density	2000 US Census, Oak Ridge National Laboratory LandScanTM
Built Space	Density of built space by land use category	NYC Department of City Planning Primary LandUse Tax Lot Output (PLUTO™)
Permitted Emissions	Permitted combustion sources, solvent use industries (excluding dry cleaning), petroleum bulk storage locations	NYS Department of Environmental Conservation, NYC Department of Environmental Protection
Transportation and waste transfer facilities	School bus depots, waste transfer stations, wastewater treatment facilities, marine terminals, airports	NYC Department of Citywide Administrative Services, NYC Department of Education, NYC Department of Sanitation, NYC Office of Emergency Management

Calculated within 50 m buffers between 50 to 500 meters and 100 m buffers between 500 to 1000 meters.