Commission approves health benchmarks for five toxic air pollutants

Benchmarks fulfill legislative mandate and provide science-based guidance for evaluating exposure

Denver (September 19, 2025): The Colorado Air Quality Control Commission has adopted health-protective benchmarks for benzene, ethylene oxide, formaldehyde, hexavalent chromium compounds, and hydrogen sulfide. These benchmarks meet a requirement of the state’s Public Protections from Toxic Air Contaminants Act (HB 22-1244) and give Colorado a science-based foundation for evaluating long-term exposure to priority air toxics.

The benchmarks identify levels of pollutants below which adverse health effects are not expected to occur, including for children, older Coloradans, and people with existing health conditions.

“Colorado is meeting its legislative mandate to establish health benchmarks for priority air toxics,” said Michael Ogletree, Senior Director of State Air Quality Programs. “By using leading science and input from both communities and industry, the state has created public health benchmarks that could help guide future policy conversations while providing clarity today about exposure levels.”

Why it matters:

• The new benchmarks fulfill a requirement set forth in the Public Protections from Toxic Air Contaminants Act (HB 22-1244), which directed Colorado to develop “health-based standards” for priority air toxics.
• Air toxics are pollutants that cause or are suspected of causing cancer, birth defects, and other serious health effects.
• The benchmarks consider both cancer and non-cancer risks, and are based on continuous lifetime exposure with a margin of safety.
• The Air Pollution Control Division consulted a technical working group and evaluated how other states developed similar benchmark values.

Next steps:

• The standards will be submitted to the Colorado General Assembly in December 2025, as required under HB 22-1244.
• The Air Pollution Control Division is also seeking feedback until October 2, 2025 on a related report exploring whether a permitting program — if authorized and funded by the legislature — could use these benchmarks to calculate risks and require actions to reduce exposure.
• The Air Pollution Control Division will present the benchmarks and the report at the January 2026 SMART Act hearings.
• Every five years, the Air Quality Control Commission will review the benchmarks and may identify additional priority air toxics.

For detailed background, including how each pollutant affects health, where it comes from, and how Colorado calculated the benchmarks, read the rulemaking hearing materials or visit the priority air toxics web page.

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