An Activity Pattern Data is in an inhalation exposure assessment, activity pattern data depict both the actual physical activity (including an associated inhalation exertion level), the physical location, and the time of the day the activity takes place (e.g., sleeping at home at midnight, jogging in the park at 8 a.m., or driving in a car at 6 p.m.). The HAPEM4 model extracts activity pattern data from the EPA's Comprehensive Human Activity Database (CHAD).