Applications of an acute assessment methodology used for combustion facilities

Two approaches for evaluating potential health impact from short-term (1 hour) inhalation exposure to air emissions from combustion facilities are presented. This information was included as part of the health risk assessment (HRA) conducted for each proposed facility in conjunction with regulatory requirements for obtaining an operating permit. Since the facilities being evaluated have either not yet been constructed or are not yet operational, air concentrations (particulate and vapor) must first be estimated using data from similar and operational facilities. A chemical's modeled air concentration was then compared to its acute toxicity value (ATV) selected from established Occupational Exposure Limits (OEL) or acute toxicity databases, if available. Analogous to the current USEPA approach for estimating noncancer health effects, acute hazard quotients (AHQs) were summed and compared to a level of one. When the summation of the AHQs exceeded unity, the chemicals were separated by target organ and health effects based on acute exposures. The author recognizes that the use of OELs has its limitations. However, due to the lack of acute toxicity data and the advantage of the completeness of the databases for OELs, this approach may be the best way to evaluate for acute health concerns for the more than 70 compounds that may be emitted from these facilities.