ABSTRACT
Concentrations measured at †xed locations can differ substantially from those made by personal exposure assessments made in the very same microenvironments (Breslin et al., 1967; Rodes et al., 1991). Only the most ubiquitous and evenly distributed contaminants provide comparable data when monitored either way. The concept that simplistic measurements of concentration do not necessarily reªect actual human exposures can be illustrated by the classical risk paradigm (Rodes and Wiener, 2001):
Sources Emissions Concentrations Doses Effects→ → → → →Exposures
where sources produce emissions that result in microenvironmental concentrations via some dispersion/transformation process that can lead to exposures-if the individual encounters the stressors across both time and space domains. Exposures are dependent on many inªuencing factors, and especially time-weighted proximity to the emissions from both distant and localized sources. The encountered exposure scenarios can produce signi†cant body doses, dependent upon inªuencing uptake factors for that exposure route, such as the ventilation (inhalation) rate for air exposures.
