Table 2.
LUR covariates (Figure 2 abbreviations) and (where applicable) covariate buffer sizes that made it through preprocessing and were considered by PLS.
| Abbreviation | Variable description | Buffer sizes |
|---|---|---|
| Distance to features | A1 roada | NA |
| Nearest roada | NA | |
| Airporta | NA | |
| Large airporta | NA | |
| Porta | NA | |
| Coastlinea,b | NA | |
| Commercial or service centera | NA | |
| Railroada | NA | |
| Rail yarda | NA | |
| SO2 | SO2 Emissionsc | 30km |
| PM2.5 | PM2.5c,d | 30km |
| PM10 | PM10c,d | 30km |
| NOx | NOxc | 30km |
| Population | Population density | 500m, 1km, 1.5km, 2km, 2.5km, 3km, 5km, 10km, 15km |
| NDVI–winter | Median winter | 250m, 500m, 1km, 2.5km, 5km, 7.5km, 10km |
| NDVI–summer | Median summer | 250m, 500m, 1km, 2.5km, 5km, 7.5km, 10km |
| NDVI–Q75 | 75th percentile | 250m, 500m, 1km, 2.5km, 5km, 7.5km, 10km |
| NDVI–Q50 | 50th percentile | 250m, 500m, 1km, 2.5km, 5km, 7.5km, 10km |
| NDVI–Q25 | 25th percentile | 250m, 500m, 1km, 2.5km, 5km, 7.5km, 10km |
| Transport | Transportation, communities, and utilities | 750m, 3km, 5km, 10km, 15km |
| Transition | Transitional areas | 15km |
| Stream | Streams and canals | 3kmd, 5km, 10km, 15km |
| Shrub | Shrub and brush rangeland | 1.5km, 3km, 5km, 10km, 15km |
| Residential | Residential | 400m, 500m, 750m, 1km, 1.5km, 3km, 5km, 10km, 15km |
| Other urban | Other urban or built-up | 400md, 500m, 1.5km, 3km, 5km, 10km, 15km |
| Mixed range | Mixed rangeland | 3km, 5km, 10km, 15km |
| Mixed forest | Mixed forest land | 750m, 1km, 1.5km, 3km, 5km, 10km, 15km |
| Lakes | Lakesd | 10 km |
| Industrial | Industrial | 1kme, 1.5kme, 3km, 5km, 10km, 15km |
| Indust/comm | Industrial and commercial complexesd | 15km |
| Herb range | Herbaceous rangeland | 3kmd, 5km, 10km |
| Green | Evergreen forest land | 400m, 500m, 750m, 1km, 1.5km, 3km, 5km, 10km, 15km |
| Forest | Deciduous forest land | 750m, 1km, 1.5km, 3km, 5km, 10km, 15km |
| Crop | Cropland and pasture | 400m, 500m, 750m, 1km, 1.5km, 3km, 5km, 10km, 15km |
| Comm | Commercial and services | 500m, 750m, 1km, 1.5km, 3km, 5km, 10km, 15km |
| A23 | Total distance of A2 and A3 roads within buffer | 100m, 150m, 300m, 400m, 500m, 750m, 1km, 1.5km, 3km, 5km |
| A1 | Total distance of A1 roads within buffer | 1km, 1.5km, 3km, 5km |
| Most variables were used in each of the four PM2.5 component models; however, the pre-processing procedure selected some variables for EC and OC that were not selected for Si and S, and vice versa because EC and OC monitoring locations were not identical to Si and S locations.aTruncated at 25km and log10 transformed. blog10 and untransformed values both included. cTons per year of emissions from tall stacks. dVariable used for modeling Si, S only. eVariable used for modeling EC and OC only. | ||