Geospatial Science & Technology Support to ATSDR

ATSDR conducts site-based work with state and local health officials to protect communities from dangerous health effects associated with exposure to hazardous contaminants in the environment. The Geospatial Research, Analysis, and Services Program (GRASP) supports ATSDR by providing geospatial analyses and visualizations that enable scientists and communities to better understand environmental, sociodemographic, and other issues associated with chemical exposures across the United States. ATSDR’s various site-based work includes Public Health ConsultationsExposure Investigations, Public Health Advisories, and Public Health Assessments (PHA) to identify and assess possible harmful exposures to hazardous substances and guide public health actions that protect the health of a community.

GRASP support to ATSDR overview
Interested? Check out ATSDR and the Division of Community Health Investigations (DCHI).


Public Health Impact: GRASP helps ATSDR scientists and communities understand relationships between environmental, demographic, and behavioral interactions with chemical exposures at hazardous waste sites.

Partner(s): ATSDR

Geospatial Expertise Provided: Geographic Information Systems (GIS), and geospatial science, technology, and visualization

The PHA Process: The Importance of Geospatial Science, Technology, and Visualization

GRASP and ATSDR conduct ongoing planning, implementation, and evaluation of data and mapping projects to identify ways to improve PHA site work. In Fiscal Year (FY) 2018, GRASP supported 40 ATSDR site assessments, which included PHAs. In FY 2019, GRASP supported ATSDR’s site investigations at 90 different locations across the United States to provide timely geospatial support, including custom cartographic (mapping) output and environmental sampling data screening and analysis. When supporting a PHA, GRASP uses Census data at the block, block group, and tract levels, and base map data, such as transportation, water features, and parks.

During the beginning stages of a PHA, ATSDR systematically gathers data and other materials to evaluate exposure to environmental contaminants. GRASP provides ATSDR researchers with demographic data, at-risk population estimates, and contextual land use information (e.g., aerial photos, topography, zoning, and land cover). By using satellite imagery, written site descriptions, and GIS land parcel boundary data, GRASP enhances ATSDR scientists’ ability to establish the site boundary and visualize the distribution and range of contaminates of concern.

GRASP also generates 1-, 3-, and 5-mile buffers of the sites to establish broad areas for additional analysis. GRASP uses these site buffers to characterize the community’s demographics, natural features, and transportation network by mapping and analyzing the environmental samples and additional site data. To assess other potential pollution or hazardous sites in the area, GRASP analysts identify nearby industrial facilities where hazardous substances are stored, handled, or released. The sites can then be sorted by pathway (how there might be exposure), or chemical of interest to account for multiple exposures that may be experienced by the community.

In the later stages of a PHA, ATSDR conducts a health effects evaluation to determine who is at risk of exposure. Using GIS data (e.g., census demographics, aerial photography, social vulnerability, lead exposure vulnerability, and day/night populations density), GRASP scientists analyze population density, movement, and socioeconomic characteristics across time and space. They repeat the process as necessary as new sampling data become available. With the data gathered in each PHA, ATSDR can make conclusions and recommendations for appropriate public health actions to prevent harmful exposures.

To learn more about PHAs, view the full Public Health Assessment Guidance Manual on ATSDR’s website.

Why Place Matters

ATSDR and other agencies use PHAs to identify whether a health study is appropriate, or whether some other public health action is warranted, such as community health education. Geography is an important part of PHAs; hazardous exposures happen within communities, and population interactions with the environment can vary from place to place. As a result, place and geographic relationships between populations and environmental hazards influence human health. For this reason, each PHA involves a vital component of geospatial science, analysis, or technology, which is the key role that GRASP plays in the PHA process.

GRASP has supported ATSDR’s site-based efforts since 1989, using geographic information systems (GIS) to collect, store, manipulate, analyze, and display data, to characterize populations living around hazardous waste sites and other sites of concern. In 1995, GRASP designed the GIS Introductory (Intro) Map, a map product created to help scientists understand the community and examine chemical exposures occurring in and around hazardous waste sites across the U.S. ATSDR has since directed it to be included in every PHA process.

GIS and geospatial science allow GRASP scientists and other public health professionals to:

  • Characterize areas of contamination and affected populations;
  • Analyze and display spatial and temporal (time-related) features, trends, and relationships; and
  • Communicate complex concepts and ideas.

Ongoing Collaboration for Healthy Communities

GRASP is committed to helping ATSDR scientists and communities understand relationships between environmental, demographic, and behavioral interactions with chemical exposures at hazardous waste sites across the United States. GRASP is collaborating with ATSDR and the National Center for Environmental Health (NCEH) to develop revised Cancer Cluster Guidelines, which will improve the science used to assess potential cancer clusters across the United States.

GRASP’s geospatial science and technology team is continuously working with ATSDR colleagues to explore ways to enhance and communicate site support by conducting complex environmental health analysis for a variety of projects, including the ongoing assessment at the Camp Lejeune site in North Carolina. To support ATSDR’s work investigating exposure to and possible health effects associated with per-and polyfluorinated substances (PFAS) in more than 30 communities across the United States, GRASP uses GIS to identify key sites, geocode locations, conduct exposure analysis, perform network analysis, and visualize data to improve research.

Helpful Terms & Facts

Public Health Assessments (PHA) evaluate a hazardous waste site for hazardous substances, health outcomes, and community concerns.

Public Health Consultations can address public health issues such as a chemical or radiological contamination, epidemiology, or provide technical advice on sampling and remediation plans.

Exposure Investigations involve the collection and analysis of environmental contamination data and biologic tests (when appropriate). The goal is to determine whether people have been exposed to hazardous substances.

Public Health Advisory is an official notice that ATSDR gives to U.S. EPA or to a state regulatory agency. The advisory identifies an immediate threat to human health from a hazardous substance. The advisory also includes a recommendation to reduce exposure and any threat to human health.


GRASP Introductory Map Series prepared for sites across the U.S.


ATSDR Site Investigations supported


PHAs/HCs published in FY19 with GRASP support

ATSDR also conducts public health consultations, exposure investigations, and public health advisories, which have a different approach and purpose than PHAs. Learn more about their uses and how they differ from PHAs here.

Person at a desk holding a tablet that has a map of the United States and a bar graph.

Page last reviewed: September 15, 2020