Human Exposure Modeling -
   Air Pollutants Exposure Model
    (APEX/ TRIM.Expo _Inhalation)

• General Information. The Air Pollutants Exposure Model (APEX) is a PC-based model that was derived from the probabilistic NAAQS Exposure Model for carbon monoxide (pNEM/CO). A draft report describing pNEM/CO is available. Reports describing prior OAQPS applications of the pNEM to ozone also are available. APEX serves as the human inhalation exposure model within the Total Risk Integrated Methodology (TRIM) model framework. See TRIM - General Information page for historical information about TRIM and peer review of the TRIM and TRIM.Expo approach. APEX is intended to be applied at the local, urban, or consolidated metropolitan area scale and currently only addresses inhalation exposures. The model simulates the movement of individuals through time and space and their exposure to the given pollutant in various microenvironments (e.g., outdoors, indoors residence, in-vehicle). The user may choose the number and types of microenvironments to be included, select the time period of interest, use either monitored ambient air quality data or values provided from dispersion or other modeling runs, and use either a mass balance approach or an empirical ratio-based (factor) approach to estimate indoor and/or in-vehicle concentrations. OAQPS is releasing the current version of APEX (version 3.2.3) as a beta version to the broader exposure modeling community. We recognize that there are areas where the model may be refined to be more useful and more user-friendly. However, the model provides a useful and informative tool for inhalation exposure modeling. We look forward to feedback from the larger modeling community on model performance and evaluation to help guide further model refinement.

• Download Model

• User's and Programmer's Manual. Those planning to use APEX are strongly encouraged to carefully review Volume I, User's Guide. It describes the scientific basis for the APEX model and describes the steps involved in running APEX for both basic and more advance applications. Volume II, Programmer's Guide (available soon) describes the model and computer code in more detail and thus provides advanced users with greater understanding of the model and includes guidance for implementing advanced options and capabilities.

• Example Applications
  1. Carbon monoxide for Los Angeles area
     1. Input Files
     2. Output Files
     3. Volume IV, User's Guide (available soon)
  2. Benzene and Chromium (Houston test application).
     1. All Files
     2. Volume III, User's Guide (available soon)

• Peer Review and Publications

• Presentations at Scientific Meetings and Conferences

  Annual Meeting of the International Society of Exposure Analysis, 4-8 November, 2001. Charleston, South Carolina
  

  Overview of APEX (2.0): EPA's Pollutant Exposure Model for Criteria and Air Toxic Inhalation Exposures. Richmond H, Palma T, Glen G, Smith L.

  Joint Meeting of the Society of Exposure Analysis and International Society of Environmental Epidemiology. 11-15 August, 2002. Vancouver, Canada.

  Further Refinements and Testing of APEX (3.0): EPA's Population Exposure Model for Criteria and Air Toxic Inhalation Exposures. Richmond HM, Palma T, Langstaff J, McCurdy T, Glenn G, Smith L. (PowerPoint file with poster)

• Other Supporting Documents
  Comparison of HAPEM5 and APEX3, technical memorandum

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