The data sources are described in detail elsewhere [15 (
link)]. Briefly, data sources were considered for EQI inclusion based on temporal, spatial, and quality-related criteria. Temporal appropriateness required data to represent the 2000 to 2005 time period. Data sources were considered spatially appropriate if data were available at, or could be aggregated or interpolated to represent, the county level for all 50 states. Data quality, especially related to data source documentation, was determined by data source managers (in data reports and internal documentation), project investigators, and with the larger field of environmental research, through use and critique of the various data sources.
The air domain included two data sources: the Air Quality System (AQS) [16 ], which is a repository of national ambient air concentrations from monitors across the country for criteria air pollutants; and the National-Scale Air Toxics Assessment (NATA) [17 ], which uses emissions inventory data and air dispersion models to estimate non-residential ambient concentrations of hazardous air pollutants (HAPs).
The water domain comprised five data sources: Watershed Assessment, Tracking < Environmental Results (WATERS) Program Database [18 ], Estimates of Water Use in the U.S. [19 ], National Atmospheric Deposition Program (NDAP) [20 ], Drought Monitor Network [21 ], and National Contaminant Occurrence Database (NCOD) [22 ]. The WATERS Program Database is a collection of data from various EPA-conducted water assessment programs including impairment, water quality standards, pollutant discharge permits, and beach violations and closures. The Estimates of Water Use in the U.S. is calculated by the United States Geological Survey (USGS) and includes county-level estimates of water withdrawals for domestic, agricultural, and industrial uses. The NDAP dataset provides measures of chemicals in precipitation using a network of monitors located throughout the U.S. The Drought Monitor Data provides raster data on the drought status for the entire U.S. on a weekly basis. The NCOD dataset provides data from public water supplies on 69 different contaminants.
The land domain was constructed using data from five sources. The 2002 National Pesticide Use Database [23 ] estimates state-level pesticide usage based on pesticide ingredients and crop type. The 2002 Census of Agriculture [24 ] is a summary of agricultural activity, including information about crops, livestock, and chemicals used. The National Priority Site data [25 ] includes location of and information on sites that have been placed on the National Priority List (NPL), including indicators for major facilities (e.g., Superfund sites), large quantity generators, toxics release inventory, Resources Conservation and Recovery Act treatment, storage and disposal facilities, corrective action facilities, assessment, cleanup, and redevelopment exchange (brownfield sites), and section seven tracking system pesticide producing site locations. The National Geochemical Survey [26 ] contains geochemical data (e.g., arsenic, selenium, mercury, lead, zinc, magnesium, manganese, iron, etc.). The fifth source is the EPA Radon Zone Map [27 ], which identifies areas of the U.S. with the potential for elevated indoor radon levels.
The sociodemographic domain included two data sources: the U.S. Census [28 ] and Federal Bureau of Investigation (FBI) Uniform Crime Report (UCR) [29 ]. The U.S. Census collects population and housing data every 10 years, economic and government data every five years and the American Community Survey annually. FBI UCR rate data are available annually and by crime type (violent or property).
The built environment domain employed five data sources. Dun and Bradstreet collects commercial information on businesses and contains more than 195 million records [30 ]. These data are the only data used in the EQI which are not free, though they are publically available for purchase. Topographically Integrated Geocoding Encoding Reference (TIGER) [31 ] data provides maps and road layers for the U.S. at multiple units of census geography. The Fatality Analysis Reporting System (FARS) [32 ] data is a national census providing the National Highway Traffic Safety administration yearly reports of fatal injuries suffered in motor vehicle crashes. Housing and Urban Development (HUD) [33 ] data provide a count of low-rent and section-eight housing in each housing authority area, which corresponds to cities. The built environment domain also included the percent using public transportation variable from the census, which was not included in the sociodemographic domain; census data have been previously described.
Messer L.C., Jagai J.S., Rappazzo K.M, & Lobdell D.T. (2014). Construction of an environmental quality index for public health research. Environmental Health, 13, 39.