Code of Colorado Regulations · Regulation Number 30

Code of Colorado Regulations · Regulation Number 30

TOXIC AIR CONTAMINANTS 5 CCR 1001-34

Regulation Number 30 covers toxic air contaminants (TACs), with a focus on priority toxic air contaminants (PTACs). It is organized into Part A (general provisions for toxic air contaminants), Part B (priority toxic air contaminants), and Part C (statements of basis, specific statutory authority and purpose), plus two appendices. The appendices list the five PTACs currently identified (benzene, hexavalent chromium compounds, ethylene oxide, formaldehyde, and hydrogen sulfide), each with a date identified of 1/17/2025, and their chronic health-protective benchmarks for cancer and non-cancer effects.

I.A.2.

Plain-language summary:

A hazard quotient (HQ) is a number that estimates the risk of non-cancer health effects from breathing a toxic air contaminant that has a Reference Concentration (RfC). It's calculated by dividing the air concentration by the RfC. An HQ above 1 means the air concentration is higher than the non-cancer RfC.

I.A.3.

"Inhalation unit risk" (IUR) is an estimate of the increased cancer risk from breathing in a specific toxic air contaminant continuously at a concentration of 1 microgram per cubic meter for a lifetime.

I.A.4.

A chronic health-protective benchmark is a health-based standard, as defined in section 25-7-109.5(1)(e), C.R.S., for each PTAC that the Commission has identified, representing an ambient air concentration below which adverse health effects are unlikely to occur from exposure to that individual PTAC alone. It is informed by the considerations in section 25-7-109.5(6)(b), C.R.S.

I.A.6.

"Reference concentration" (RfC) is an estimate of the airborne concentration of a specific toxic air contaminant that people (including sensitive groups) can breathe continuously over a lifetime and that is likely to be without risk of harmful effects. The estimate carries uncertainty, perhaps spanning an order of magnitude.