The AAAQGs. The Arizona Department of Health Services (ADHS) has developed a list of AAAQG levels. These levels were derived by making an adjustment for the differences in the averaging times for exposure and applying a safety factor to limits originally established to protect individuals exposed in occupational settings. For example, occupational exposure levels are intended to be safe for individuals exposed to those levels for 8 hours per day, 7 days per week for a working lifetime. They generally assume an 8-hour average exposure time; however, longer average times (e.g., 24 hours) are more appropriate for establishing community health guidelines. In addition, a safety factor is applied to provide adequate protection for the general public, which includes people who may be more sensitive than workers (e.g., children and the elderly). The AAAQGs established by ADHS are for guidance purposes only and are not intended for use in deriving regulatory limits. Notwithstanding the non-binding nature of the AAAQGs, Intel, in cooperation with the stakeholders involved in the XL Project, employed these levels to provide additional assurance that the PSELs in the FPA and air permit are protective of public health. In addition, to address concerns raised by stakeholders regarding non-HAP chemicals, Intel also analyzed chemicals emitted from the Ocotillo Site that, while not HAPs, have established AAAQGs. Intel also has agreed in the FPA to work cooperatively with the ADHS and MCESD to evaluate the public health implications and establish limits if necessary for any chemicals it may introduce to the air in the future that are associated with potential health concerns, regardless of whether such chemicals are HAPs or have an established AAAQG. Finally, Intel has agreed under the FPA to apply the screening analysis to maximum onsite ambient air concentrations of chemicals modeled under the FPA. The AAAQGs are well suited for the screening analysis described herein because they are likely to be conservative (i.e., err on the side of public health by setting levels well below what would be likely to cause adverse effects in the general population). This conservative approach, combined with the conservative assumption that screened chemicals will be emitted at 10 tons per year in the case of HAPs (or at the predicted emissions rate for any non-HAP if such rate is greater than 10 tons per year), make this screening analysis a useful tool in providing an additional assurance that air ...
