PM exposure variations due to different time activity profile simulations within a single dwelling

Abstract

This paper describes the combination of a physical pollutant model IAPPEM with a time activity profile, to create an air pollutant personal exposure model. A previous study has already demonstrated the capability of IAPPEM in predicting indoor Particulate Matter (PM) concentrations in a residential environment. The present work investigates personal exposure variability between individuals and, doors opened vs closed scenarios, by examining the movements of four individuals through the same dwelling. The results of the simulations highlight the distinction between personal exposure and indoor concentrations, providing computational validation to well-documented experimental differences that exist between indoor concentrations and personal exposure. Using IAPPEM, personal exposure is calculated according to the percentage contribution from the time spent in each room, illustrating that the periods of presence, in relation to the times of indoor source emission, are as important as the durations spent in each room.This study provides a comparison between two approaches for evaluating personal exposure: a time-weighted average and a time activity profile. The results showed that a time-weighted averaged profile is a poor substitute when compared with personal exposure calculated based on a time activity profile, as, in each simulated scenario, exposures were under-predicted using the time-weighted approach, in some cases by up to 135%.