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Human Health Risk

Human Health Risk

Exposure to air contaminants may increase risk for respiratory disease and compromised immune systems, as well as cause neurological, reproductive, and developmental harm. Assessing these risks and identifying the sources that cause them is critical to finding solutions to protect public health. SC&A has a long history of performing risk analyses and developing powerful risk assessment tools, and of identifying emission reduction strategies and programs to reduce these risks.

We provide these and related services:

  • Assess acute and chronic human health risks at the national, regional, and community level
  • Evaluate the risks to various populations by income, race, education, and many other socioeconomic groupings (i.e., environmental justice evaluations)
  • Identify high-risk locations and the sources of the emissions causing these high risks
  • Use modeling and risk assessment results to design ambient monitoring networks
  • Evaluate emission reduction measures at industrial sources to reduce risks
  • Identify transportation and mobile source programs to reduce risks
  • Develop regulatory programs and policies to reduce risks

Sample Projects

Residual Risk Assessments. In this ongoing program, SC&A has performed hundreds of exposure and risk analyses for industrial sectors under the U.S. Environmental Protection Agency’s (EPA’s) Residual Risk and Technology Review program. We estimated cancer and chronic and acute noncancer risks due to the inhalation of hazardous air pollutants for populations residing near industry sector operations, and we identified the specific sources contributing most to these risks.

Human Exposure Model. SC&A developed the Human Exposure Model, Version 3 (HEM-3) with AER-MOD, a powerful tool that can be used for estimating ambient air concentrations and assessing risks and impacts to those residing near sources of toxic air pollutants. SC&A is currently under contract with the EPA to develop the next generation of HEM. HEM-4 will retain all the functionality of HEM-3 plus user interfaces developed using state-of-the-art open source code. See the EPA HEM page to learn more about HEM-3.

Transportation Corridor Hot Spot Analyses. SC&A prepared Mobile Source Air Toxics (MSAT) air quality hot spot analyses for the Virginia Department of Transportation that were needed to fulfill NEPA and Clean Air Act conformity requirements for several major corridors in the Washington, DC, metropolitan area.

Environmental Justice Tools and Analyses. SC&A has developed several tools for the EPA to help evaluate the environmental justice impacts of environmental hazards and regulatory programs on different socioeconomic and demographic groups.

National Air Toxics Assessment. For over a decade, SC&A has supported EPA’s National Air Toxics Assessment (NATA). In this assessment, we estimated cancer risks and noncancer risks across the nation for toxic air pollutants from over 65,000 industrial facilities, as well as from onroad and nonroad mobile source impacts for over 70,000 census tracts. For more information, see the EPA NATA page. SC&A is also supporting the successor to NATA, which will provide annual updates of the nationwide risks to air toxics.

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