Download Human Exposure Model (HEM)

1. Hardware/Software Requirements. You can use HEM5.0 on any Windows™-based personal computer running Windows 98™ or later. Disk space requirements will depend on the number of meteorological files that you use. If using HEM5.0 to model only facilities in a single state, then only the meteorological data for that state need to be extracted from the zip file, and the model would require less disk space. To use all the nationwide meteorological files, 1.7 gigabytes of disk space are needed. The model also will need a minimum of 8 gigabytes of RAM.
2. Download documentation files from HEM home page, and review information on installing and configuring HEM5.0.
3. Download the HEM5.0 zip file. (See Section 2 below.)
4. Select the directory on your computer to install HEM5.0 and unzip/extract the contents into that directory. The basic files needed to run HEM5.0 will be placed in that directory. A number of subdirectories will also be created.
5. To complete the installation of HEM5.0, the Input Files provided in Section 3 below must be downloaded to your PC. Each .ZIP file must be unzipped, and the contents placed in a particular subdirectory of the HEM5 installation directory. Place the Toxicity Value Files in the resources subdirectory (HEM5.0\resources), the Census File in the census subdirectory (HEM5.0\census), and the Meteorological Files in the MetData subdirectory (HEM5.0\aermod\MetData).

• Toxicity Value Files

  •   HEM Toxicity Value Files (zip)  (May 2025) - This .ZIP file must be unzipped, and the contents placed in the resources subdirectory (HEM5.0\resources). The HEM5.0.zip already includes these two toxicity value files, so you will need to replace those two files with the latest files posted here.
    
    These include a set of acute and chronic dose-response values compiled by OAQPS for purposes of RTR screening-level analyses; for some chemicals, surrogate values, identified based on policy considerations for these specific purposes, have been included. Users should review and confirm values are appropriate for their uses, making corrections or updates as needed prior to using. An accompanying file identifies the target organs associated with the chronic values.

• Census File

  • Nationwide 2020 Census File (zip)  (May 2025) - Note: HEM5.0 was designed to use one combined 2020 census file. This .ZIP file must be unzipped, and the contents placed in the census subdirectory (HEM5.0\census).

• Meteorological Files

  • Nationwide Meteorological Data Files for 2019 (zip)  (updated 2022) - This .ZIP file must be unzipped, and the contents placed in the MetData subdirectory (HEM5.0\aermod\MetData).

1. Hardware/Software Requirements. You can use HEM4.2 on any Windows™-based personal computer running Windows 98™ or later. Disk space requirements will depend on the number of census and meteorological files that you use. If using HEM4.2 to model only facilities in a single state, then only the census and meteorological data for that state need to be extracted from the zip file, and the model would require less disk space. To use all the nationwide Census and meteorological files, 3.3 gigabytes of disk space are needed. The model also will need a minimum of 8 gigabytes of RAM.
2. Download documentation files from HEM home page, and review information on installing and configuring HEM4.2.
3. Download the HEM4.2 zip file. (See Section 2 below.)
4. Select the directory on your computer to install HEM4.2 and unzip/extract the contents into that directory. The basic files needed to run HEM4.2 will be placed in that directory. A number of subdirectories will also be created.
5. To complete the installation of HEM4.2, the Input Files provided in Section 3 below must be downloaded to your PC. Each .ZIP file must be unzipped, and the contents placed in a particular subdirectory of the HEM4 installation directory. Place the Toxicity Value Files in the resources subdirectory (HEM4\resources), the Census Files in the census subdirectory (HEM4\census), and the Meteorological files in the MetData subdirectory (HEM4\aermod\MetData).

• Toxicity Value Files

  • HEM Toxicity Value Files (zip)  (May 2025) - This .ZIP file must be unzipped, and the contents placed in the resources subdirectory (HEM4\resources).
    
    These include a set of acute and chronic dose-response values compiled by OAQPS for purposes of RTR screening-level analyses; for some chemicals, surrogate values, identified based on policy considerations for these specific purposes, have been included. Users should review and confirm values are appropriate for their uses, making corrections or updates as needed prior to using. An accompanying file identifies the target organs associated with the chronic values.

• Census Files

  • Nationwide 2020 Census files (zip)  (September 2024) - Note: HEM4.2 was designed to use 2020 census files. This .ZIP file must be unzipped, and the contents placed in the census subdirectory (HEM4\census).

• Meteorological Files

  • Nationwide Meteorological Data Files for 2019 (zip)  (updated 2022) - This .ZIP file must be unzipped, and the contents placed in the MetData subdirectory (HEM4\aermod\MetData).

4. Available Tool

• Block Check Tool

  Starting with HEM4.2, the 2020 Block Check Tool is available to assist users in determining the locations of receptors to remove from the Census files, move to a different location, or add to the Census files.

  • Instructions

    • Download the 2020_Block_Check_Tool.zip and unzip this folder on your computer. Download the two "Resource" files (Census2020_US_HEM.zip, and 2020_Block_Polygons_Final.zip). Place the unzipped versions of these two files into the “Resources” folder of the unzipped 2020 Block Check Tool. To use the tool, double click on the “BlockCheckTool.exe” to start the program. Follow the user instructions given in the 2020_Block_Check_Tool_Guide.pdf

  • Tool Guide

    • 2020 Block Check Tool Guide (pdf) (98.59 KB)  (September 2024)

  • Software Available for Download

    • 2020 Block Check Tool (zip)  (September 2024)

  • Resource Files

    • Census2020_US_HEM (zip) (September 2024)
    • 2020_Block_Polygons_Final (zip) (September 2024)

1. Hardware/Software Requirements. You can use HEM4.1 (and the RTR summary programs) on any Windows™-based personal computer running Windows 98™ or later. Disk space requirements will depend on the number of census and meteorological files that you use. If using HEM4.1 to model only facilities in a single state, then only the census and meteorological data for that state need to be extracted from the zip file, and the model would require less disk space. To use all the nationwide Census and meteorological files, 2.2 gigabytes of disk space are needed. The model also will need a minimum of 132 megabytes of RAM.
2. Download documentation files from HEM home page, and review information on installing and configuring HEM4.1.
3. Download the HEM4.1 zip file. (See Section 2 below.)
4. Select the directory on your computer to install HEM4.1 and unzip/extract the contents into that directory. The basic files needed to run HEM4.1 will be placed in that directory. A number of subdirectories will also be created.
5. To complete the installation of HEM4.1, the Input Files provided in Section 3 below must be downloaded to your PC. Each .ZIP file must be unzipped, and the contents placed in a particular subdirectory of the HEM4 installation directory. Place the Toxicity Value Files in the resources subdirectory (HEM4\resources), the Census Files in the census subdirectory(HEM4\census), and the Meteorological files in the MetData subdirectory (HEM4\aermod\MetData).

• Toxicity Value Files

  • This .ZIP file must be unzipped, and the contents placed  in the resources subdirectory (HEM4\resources).
    
    These include a set of acute and chronic dose-response values compiled by OAQPS for purposes of RTR screening-level analyses; for some chemicals, surrogate values, identified based on policy considerations for these specific purposes, have been included. Users should review and confirm values are appropriate for their uses, making corrections or updates as needed prior to using. An accompanying file identifies the target organs associated with the chronic values.

  • These files are available via link in Section 3 of HEM4.2 above.

• Census Files

  • Nationwide 2010 Census files (zip)   (March 2023) - Note: HEM4.1 was designed to use 2010 census files. This .ZIP file must be unzipped, and the contents placed in the census subdirectory (HEM4\census).

• Meteorological Files

  • These files are available via link in section 3 of HEM4.2 above. This .ZIP file must be unzipped, and the contents placed in the MetData subdirectory (HEM4\aermod\MetData).

• Human Exposure Modeling - General Information
• Fate, Exposure, and Risk Models Download Page
• Fate, Exposure, and Risk Analysis Home Page