Table 1.
Variables considered for spatial prediction models for PM10–2.5 mass and chemical component concentrations.
| Variable | Unit | Buffer radii |
|---|---|---|
| Abbreviations: NA, not applicable; NDVI, Normalized Difference Vegetation Index. aCALINE3 long-term average concentrations of a traffic-generated inert gaseous pollutant were generated from a line source dispersion model (Wilton et al. 2010). | ||
| Land use: satellite based | ||
| Open water; developed open space; developed low intensity; developed medium intensity; developed high intensity; bare rock/sand/barren/mine; trees; shrub land; grasslands/herbaceous vegetation; pasture/hay; cultivated crops; woody wetlands. | Percent | 50, 100, 150, 300, 400, 500, 750, 1,000, 1,500, 3,000, 5,000 m |
| Land use: aerial photography based | ||
| Residential; commercial and services; industrial, transportation, communications, and utilities; other urban or built-up land; mixed urban or built-up land; strip mines, quarries, and gravel pits; industrial and commercial complexes; transitional areas. | Percent | 50, 100, 150 m |
| Local transportation | ||
| Distance to the nearest A1/A2/A3 road | Meters | NA |
| Length of A1/A2/A3 roads in buffers | Meters | 50, 100, 150, 300, 400, 500, 750, 1,000, 1,500, 3,000, 5,000 m |
| Distance to the nearest truck route/railroad/rail yard/airport/large port | Meters | |
| Length of truck routes in buffers | Meters | 100, 150, 300, 400,500, 750, 1,000, 1,500, 3,000, 5,000, 10,000, 15,000 m |
| CALINE long-term averagea | NA | 1.5, 3, 4.5, 6, 7.5, 9 km |
| Population density | Person/km2 | 3, 5, 10, 15 km |
| Ground cover | ||
| Imperviousness | Percent | 50, 100, 150, 300, 400, 500, 750, 1,000, 3,000, 5,000 m |
| NDVI in the 25th and 75th percentiles | NA | 250, 500, 1,000, 5,000 m |
| Sum PM10–2.5 emissions | Tons/year | < 3, 3–15, 3–30 km |
| Positional information | ||
| Latitude and longitude (X,Y) | Meters | NA |
| Distance to main and local city hall | Meters | NA |