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Inhalation Parameters


Inhalation exposures occur when a chemical volatized from soil is inhaled as a vapor or when soil particles containing the chemical are respired. Two parameters are needed to estimate chemical concentrations in air to determine dose from inhalation exposures: the Volatilization Factor (VF) and the Particulate Emission Factor (PEF).


Volatilization Factor


The Volatilization Factor (VF), in m3/kg, is a measure of the tendency of a chemical to volatize from soil to vapor. Volatile Organic Compounds (VOC) are defined by USEPA (1998) as chemicals with Henry’s Law constants greater than 10-5 atm-m3 /mol and molecular weights less than 200 grams/mol.


Particulate Emission Factor


The Particulate Emission Factor (PEF), expressed in kg soil/m3 air, is a measure of the amount of respirable soil particles in a volume of air. It is used to estimate chemical concentrations in air from concentrations in soil.