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  1. Home
  2. Air: Fate, Exposure, and Risk Analysis (FERA)

Human Exposure Model User’s Guides

Risk Assessment and Modeling
  • General Information
  • Air Toxics Risk Assessment
  • Criteria Air Pollutant Risk Assessment
  • Human Exposure Model (HEM)
    • HEM User's Guides
  • Links to EPA Risk Assessment Policy, Guidelines, and Related Materials

Instructions for using the Human Exposure Model (AERMOD version). Guides are available for HEM5.0, HEM4.2, and HEM4.1.

  • HEM5.0 Users Guide (pdf) (5.37 MB, May 2025)
  • HEM5.0 Model Change Bulletin (pdf) (204.92 KB, May 2025)
  • HEM4.2 Users Guide (pdf) (6.88 MB)
  • HEM4.2 Model Change Bulletin (pdf) (129.85 KB, January 2023)
  • HEM4.1 User's Guide (pdf) (7.29 MB, September 2021)
  • HEM4.1 Model Change Bulletin (pdf) (176.61 KB, September 2021)

Air: Fate, Exposure, and Risk Analysis (FERA)

  • Total Risk Integrated Methodology (TRIM)
    • TRIM.FaTE
    • TRIM.Expo
    • TRIM.Risk
    • Peer Review and Publications
  • Multimedia Fate and Transport Modeling
    • TRIM.FaTE
    • Other Models and Related Information
  • Human Exposure Assessment and Modeling
    • Criteria Air Pollutant Exposure Assessment
    • Databases to Support Exposure Modeling
    • Air Pollutants Exposure Model (APEX/ TRIM.Expo Inhalation)
    • Hazardous Air Pollutant Exposure Model (HAPEM)
    • Other Models and Exposure-Related Information
  • Risk Assessment and Modeling
    • Air Toxics Risk Assessment
    • Criteria Air Pollutant Risk Assessment
    • Human Exposure Model (HEM)
    • EPA Risk Assessment Policy, Guidelines, and Related Materials
Contact Us about FERA
Contact Us to ask a question, provide feedback, or report a problem.
Last updated on May 7, 2025
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