The Colorado Air Quality Control Commission has approved new health benchmarks for five toxic air pollutants: benzene, ethylene oxide, formaldehyde, hexavalent chromium compounds, and hydrogen sulfide. These benchmarks are designed to protect public health by setting levels below which adverse effects are not expected for all populations, including children, older adults, and those with existing health conditions.
This action fulfills a mandate from the Public Protections from Toxic Air Contaminants Act (HB 22-1244), which required the state to establish science-based standards for priority air toxics. The benchmarks address both cancer and non-cancer risks and are based on continuous lifetime exposure with an added margin of safety. The Air Pollution Control Division developed these standards in consultation with a technical working group and by reviewing how other states have set similar values.
“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.”
The next steps include submitting the new standards to the Colorado General Assembly in December 2025 as required by law. The Air Pollution Control Division is also collecting feedback until October 12, 2025 on a related report that examines whether a permitting program could use these benchmarks to calculate risks and require actions to reduce exposure if authorized by lawmakers. Both the benchmarks and this report will be presented at the January 2026 SMART Act hearings.
The commission plans to review these benchmarks every five years and may identify additional air toxics for evaluation in future cycles.
For more information about each pollutant’s health impacts or details on how the benchmarks were calculated, interested parties can consult rulemaking hearing materials or visit Colorado’s priority air toxics web page.
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