The California Air Pollution Control Officers Association (CAPCOA) is proposing to update its Facility Prioritization Guidelines for the Air Toxics Hot Spots program.  The Prioritization Guidelines, which describe the methodologies used by California air districts to identify "High Priority" facilities under the Hot Spots program, were first published in July 1990 and have never been updated.

The Prioritization Guidelines are being updated now in response to revisions to the State's underlying health risk assessment preparation guidelines, which were adopted by the Office of Health Hazard Assessment (OEHHA) in March 2015.  The only substantive change from the existing Prioritization Guidelines is to increase the cancer normalization factor, and thus the cancer priority score, by a factor of 4.53.  There are no changes to scores for acute or chronic non-cancer impacts.

If the air districts do not change their prioritization thresholds, the increase in cancer priority score will result in more existing facilities being classified as "medium" and "high" priority facilities, triggering requirements to prepare risk assessments or provide notice to surrounding residents.

The increase in the cancer normalization factor is mostly due to the OEHHA guideline's increased cancer impacts for childhood exposures.  Some California air districts have already revised their risk assessment methodologies to include this.  The impact of the new CAPCOA Prioritization Guidelines will be smaller in those districts.