Oregon moved to regulate air toxics with SB 1541, which became effective April 10, 2018. Regulations implementing the air toxics requirements were adopted by Oregon DEQ in November of 2018 and, as explained below, draft risk assessment guidance has now been released for public comment.

The agency estimates that 400 facilities will be impacted by the new regulations and it hopes to complete permitting for 20 of those facilities by the end of the first year. DEQ has not said which 20 will have that honor, but new major source facilities will need to evaluate air toxics as part of their permit applications. Facilities who were already regulated may want to obtain better data on their emissions inventory and plan ahead to minimize adverse impacts on their business.

DEQ is using a complicated prioritization formula to determine which currently permitted facilities to evaluate first under the new regulations. The formula might foreshadow complexities of the program and would make your high school algebra teacher proud. The first step in prioritization is to take the summation of the risks from emissions that are likely to cause cancer risk, non-cancer risk, and acute risks and divide each by its associated risk. This total is then taken to the 0.75 power (not something you do every day but thank goodness for calculators). It is then added to the potential impacted population of the sum of four groups (low income persons, minorities, kids under five, and the general population) that are then divided by four. This extra weighting is apparently meant to serve as some “environmental justice” for the groups counted more than once. This total is then taken to the 0.25 power – in other words the square root of the square root. Add those two numbers together and you have the quantitative “score” for prioritization. DEQ noted, however, that the assigned priority is not intended to equate with the relative risk posed by facilities.

But liberal arts majors despair not, because after completing the quantitative analysis, DEQ applies a qualitative analysis to derive the prioritization. The qualitative factors that are considered, without regard to any mathematical formulas, include the data quality going into the quantitative factor, the nearest exposure point to a facility, and existing controls that are already in place at the facility.

After reviewing all this, you can understand why DEQ doesn’t have the prioritization completed yet. But the real work ahead for facilities will entail:

• Preparing air toxics emissions inventories
• Preparing a risk assessment work plan
• Performing the risk assessment
• If needed, developing a risk reduction plan to address unacceptable risk
• Filing a permit addendum application
• Going through public notice and hearings
• Issuing a permit addressing air toxics

DEQ jumped ahead and issued draft risk assessment guidance in October 2017 and June 2018 and is currently seeking comments on its latest revision.

The complexity is inherent in aggregating risk from at least 260 chemicals where risk-based concentration limits have been established; stack emission sources and fugitive emission sources at each facility; evaluation of each chemical from each source at each of the nearest exposure points (based on zoning or where people may be known to spend more than one hour); the three kinds of potential risks that may be posed by each chemical; and 18 target organs that may be impacted. The matrix is going take up quite a bit of space.

Everyone agrees that the risk to be addressed is derived from the amount of exposure and the toxicity of the chemical at issue, but the details as to how to evaluate risk are still a work in progress, along with guidance documents for regulated facilities to navigate the new requirements. The rules are dense and some explanations only appear in response to past comments. What is clear is that the new rules will include penalties and that violations will create a stigma that might poison community relations or provide fodder for air toxics lawsuits.