Air Quality Control Commission Establishes Health-Protective Standards for Toxic Pollutants

The Colorado Air Quality Control Commission today finalized a rule establishing health-protective standards for five toxic air pollutants in the state: formaldehyde, benzene, chromium compounds, ethylene oxide, and hydrogen sulfide. Colorado will set emission limits to regulate these toxic air contaminants in an April 2026 rulemaking. Today’s rule is a result of the 2022 Public Protections for Toxic Air Contaminants law, which directed the commission to propose health-based standards for priority toxic air contaminants.

Today’s rule establishes the maximum amount of each of the five priority chosen by the AQCC in January that the commission determined can be in the air while still protecting public health from both cancer and non-cancer risk. The law required that the commission follow the best available peer-reviewed science to identify benchmark toxicity levels of pollutants that protect public health, including vulnerable populations such as disproportionately impacted communities.

The rulemaking resulted in a mixed decision with the commission choosing to follow the division and community groups’ advice to set a protective cancer risk level, which will make it one of the most protective in the country. However, the commission deviated from the division’s proposed non-cancer risk level, siding with industry to adopt significantly less protective levels for the non-cancer risk benchmark.

Earthjustice represented GreenLatinos in this week’s rulemaking.

“Colorado finally set health-based standards for toxic air, but the commission fell short,” said Patricia Garcia-Nelson, Colorado fossil fuels just transition advocate with GreenLatinos. “By choosing higher thresholds for the PTACs (Priority Toxic Air Contaminants) and siding with the industry coalition, they left communities more vulnerable than they should be. Adopting California’s benzene standard is progress, but now the division must follow through with a robust permitting program and require the best available technology to ensure these health standards deliver real protection.”

“We are disappointed that a majority of commissioners deviated from the well-researched proposal put forward by the division. This was a missed opportunity to protect Coloradans particularly in light of the deregulation we’re seeing at the federal level,” said Rachael Jaffe, associate attorney with Earthjustice’s Rocky Mountain Office. “However, we are pleased that the commission adopted a protective cancer risk level. This is a crucial step toward protecting impacted communities across the state. The state must now set the strongest possible emission limits based on these standards to hold our serial polluters accountable.”