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Human Exposure Modeling - Air Pollutants Exposure Model

APEX/TRIM.Expo Inhalation

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). Reports describing prior OAQPS applications of the pNEM to carbon monoxide and ozone 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. Results of the APEX simulations are provided as hourly and summary exposure and/or dose estimates, depending on the application, for each individual included in the simulation as well as summary statistics for the population modeled.

Three different versions of TRIM.ExpoInhalation (also known as APEX) are currently available: APEX 3.3, for use within TRIM, and two other versions of APEX (APEX 5.0 and 4.5), for stand alone use.

  • Example Applications 
  • 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, August, 2002(2 pp, 323 K) Richmond HM, Palma T, Langstaff J, McCurdy T, Glenn G, Smith L.
  • Other Supporting Documentation
Decision Points for Configuring APEX for Air Toxics Exposure Assessments - This document describes some decisions involved in configuring the Air Pollutants Exposure (APEX) model for air toxics applications and provides helpful information for making these decisions.