Table 1 Variables that were constructed and considered during the model building process
Variable | Description | Level | Type | Time | Source |
|---|---|---|---|---|---|
Outcome | |||||
 Count | Asthma ED visit count | Census tract | Count | 1999–2015 | SCRFA |
Demographics | |||||
 PERC_W | Percent of the population white race | Census tract | Continuous | 2010 | US Census |
 Per_You | Percent of the population ages 5–19 | Census tract | Continuous | 2010 | US Census |
 Per_Mal | Percent of the population male | Census tract | Continuous | 2010 | US Census |
 Per_high | Percent of the population graduated high school | Census tract | Continuous | 2010 | US Census |
 POV100 | Percent of the population < 100% federal poverty level (FPL) | Census tract | Continuous | 2010 | US Census |
 hmedinc | Household median income (scaled by $1 k) | Census tract | Continuous | 2010 | US Census |
 propmiss | Average annual proportion of census tract identifiers missing | Census tract | Continuous | 1999–2015 | SCRFA |
Weather | |||||
 Temp | Average annual temperature (℃) | Census tract | Continuous | 1999–2015 | PRISM |
 Dewp | Average annual dewpoint temperature (°C) | Census tract | Continuous | 1999–2015 | PRISM |
Air pollutants | |||||
 CO | Average annual CO concentration (ppm) | Census tract | Continuous | 1999–2015 | CACES |
 NO2 | Average annual NO2 concentration (ppb) | Census tract | Continuous | 1999–2015 | CACES |
 O3 | Average annual O3 concentration (ppb) | Census tract | Continuous | 1999–2015 | CACES |
 SO2 | Average annual SO2 concentration (ppb) | Census tract | Continuous | 1999–2015 | CACES |
 PM25 | Average annual PM2.5 concentration (μg/m3) | Census tract | Continuous | 1999–2015 | CACES |
 PM10 | Average annual PM10 concentration (μg/m3) | Census tract | Continuous | 1999–2015 | CACES |
Social | |||||
 Pharm_km | Distance to nearest pharmacy (km) | Census tract | Continuous | 2017 | SCBOP |
 tot_hour | Total hours worked in primary care by health professionals | County | Continuous | 2018 | SCRFA |
 PER_VAC | Percent houses vacant | Census tract | Continuous | 2010 | US Census |
 PPL_HOUSE | Average people per house | Census tract | Continuous | 2010 | US Census |
 Per_Urb | Percent of the population urban | Census tract | Continuous | 2010 | US Census |
 Ped_Per_Un | Percent of the pediatric population on public insurance | Census tract | Continuous | 2010 | US Census |
 Pop_km2 | Population density (people/km2) | Census tract | Continuous | 2010 | US Census |
Environmental confounders | |||||
 Ag_count | Agricultural facility count | Census tract | Count | 2018 | SCDHEC |
 Road_km2 | Road density (km road/km2 census tract area) | Census tract | Continuous | 2018 | SCDOT |
 maj_km | Distance to nearest major air pollutant emitting facility (km) | Census tract | Continuous | 2017 | US EPA |
 maj_ang_rad | Direction to nearest major air pollutant emitting facility (radians) | Census tract | Continuous | 2017 | US EPA |
 pow_km | Distance to nearest fossil fuel burning power plant (km) | Census tract | Continuous | 2017 | US EPA |
 pow_ang_rad | Direction to nearest fossil fuel burning power plant (radians) | Census tract | Continuous | 2017 | US EPA |