US EPA

This paper discusses the legal and scientific reasons for separating personal exposure to PM into ambient and nonambient components. It then demonstrates by several examples how well-established models and data typically obtained in exposure field studies can be used to estimate both individual and community average xposure to ambient-generated PM (ambient PM outdoors plus ambient PM that has infiltrated indoors), indoor-generated PM, an personal activity PM. Ambient concentrations are not highly correlated with personal exposure to nonambient PM or total PM but are highly correlated with persoanl expsure to ambient-generated PM. Therefore, ambient concentrations may be used inepidemiology as an appropriate surrogate for personal exposure to ambient-generated PM. Suggestions are offered as to how exposure to ambient-generated PM may be obtained and used in spidemiology and risk assessment.

Wilson Jr., W E., D T. Mage, AND L D. Grant. Estimating Separately Personal Exposure To Ambient And Non-Ambient Particulate Matter For Epidemiology And Risk Assessment: Why And How. JOURNAL OF THE AIR AND WASTE MANAGEMENT ASSOCIATION 50:1167-1183, (2000).