UltraSystems performs air toxics health risk assessments (HRAs) under AB 2588, Proposition 65, and South Coast Air Quality Management District SCAQMD) Rule 1401.

An HRA project typically begins with preparation of an air toxics emission inventory. UltraSystems air specialists visit the project site and identify equipment and processes that are sources of toxic air contaminant (TAC) emissions.  We also gather data on material flows, plating current, gas use, and other process rates used for calculating emissions. 

In most cases, emissions are estimated using standard references, such as the U.S. Environmental Protection Agency’s AP-42; however, some emission rate calculations require non-routine engineering analyses, for which UltraSystems has particular expertise.  During the site visit and after, we obtain and/or calculate values for the stack parameters used in subsequent modeling.  The next step is to estimate annual average and hourly ground-level pollutant concentrations, using dispersion modeling. 

UltraSystems performs all its modeling in-house, and is experienced in using the Air Resources Board’s “Hot Spots” Analysis and Reporting Program (HARP) software.  The final step is to identify the locations and magnitudes of maximum individual cancer risk for residents, off-site workers and sensitive receptors; maximum chronic non-cancer risk for residents, off-site workers and sensitive receptors; and maximum acute non-cancer risk for residents, off-site workers and sensitive receptors. 

The staff of UltraSystems is experienced in presenting the results of HRAs at public meetings, and in preparing risk reduction plans under SCAQMD) Rule 1402.

The Air and Noise Group of UltraSystems has completed health risk assessments under AB2588 and Proposition 65, as well as numerous Rule 1401 analyses to support permit applications.  In addition, UltraSystems has prepared more than 40 HRAs for new and expanded public schools for the Los Angeles Unified School District.