Geographic Information System

Geographic information system (GIS) resources can be used to map, visualize, and analyze spatial data easily. Environmental exposure investigations lend themselves to mapping. GIS tools can help determine the proximity of ECE programs to industries that use hazardous materials. This assessment can determine if the ECE program could be affected by hazardous materials from activities near the ECE program. GIS is a useful tool for identifying hazardous waste sites or releases near an existing or planned siting of an ECE program. Although it can help identify potential issues, it cannot rule out all sources of concern. Identifying a potential problem does not mean the property is not safe, but that additional investigation is warranted.


Geocoding is the process of assigning geographic coordinates (latitude and longitude) to a street address. The full street address of the ECE program should be used for geocoding to most accurately locate the building on the map. Keep in mind that some facilities list a central office address in some databases, not the site having the hazardous materials. Therefore, environmental hazards should be geocoded to the physical street address of the toxic facility for accurate results. In addition to address-match geocoding, electronic parcel data can be used, where available, to refine property locations.

Note that positional errors in geocoding can result in exposure misclassification. You can validate geocoded building locations with aerial photos or imagery available through Google street view or other commercially available imagery.

Buffer Analysis

Buffer analysis can be used in GIS to create a new polygon around a feature (ECE program) on a map to identify environmental hazard sources inside the buffer zone. The area of the buffer is determined by the radius selected by the user. Buffer analysis can identify any facilities or industries that use hazardous materials close to the ECE program. A map can then be generated that shows the location of the ECE program in relation to businesses that use hazardous waste. The map can be used to determine if the ECE programs might be at risk for exposure to emissions from the businesses.

Data Sources

Many sources are available for GIS environmental data at national, state, and local levels. Table 6.2 lists some of the websites that offer GIS data for environmental hazards.

Table 6.2. Online GIS sources with environmental hazards datasets
Source Website Description
American Community Survey, U.S. Census Bureau Census-based information for local officials, community leaders, and businesses to understand the changes taking place in their communities
American Factfinder, U.S. Census Bureau Census-based housing survey data
Defense sites, U.S. Army Corps of Engineers
Formerly used sites and related activities from Defense Environmental Restoration Program Annual Report to Congress
Department of Energy Formerly used sites
Esri data and maps (open source) General purpose base map data, including imagery and roads
EnviroAtlas, EPA National and community environmental data, redevelopment, and GIS information for consumers, environmental services
Envirofacts, EPA Air Facility System (AFS), Assessment Cleanup and Redevelopment Exchange System (ACRES), Biennial Report (BR), Comprehensive Environmental Response, Compensation and Liability Information System (CERCLIS), Green House Gas (GHG), Permit Compliance System/Integrated Compliance Information System (PCS/ICIS), Radiation Information Database (RADInfo), Resource Conservation and Recovery Act (RCRAInfo), Toxics Release Inventory (TRI), Toxic Substances Control Act (TSCA)
Local data Specific to State, County, Territory, and City Include variety of data via county health departments or city government for GIS data, parcel information, health, or environmental-related data
National Environmental Public Health Tracking Network, CDC Air, water, housing, pesticide, and toxic substances
National Priorities List, EPA Directory of maps and alphabetical listing of state and U.S. territory websites.
Wastes – Where You Live, EPA Directory of maps and alphabetical listing of state and U.S. territory websites.
Where You Live, EPA Listing of state health and environmental agencies that may provide GIS data for environmental hazards; scroll down to each state name to view the listings

Appendix C outlines the Pennsylvania Department of Health’s Health Assessment Program’s guide to using GIS for siting licensed child care centers.

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Page last reviewed: February 1, 2019