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. This decision fulfills a requirement of the state’s Public Protections from Toxic Air Contaminants Act (HB 22-1244), which directed the development of science-based standards for priority air toxics.
These benchmarks are intended to identify pollutant levels below which adverse health effects are not expected for all groups, including children, older adults, and people with existing health conditions. The commission’s approach considered both cancer and non-cancer risks based on continuous lifetime exposure and included a margin of safety.
“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.”
To develop these benchmarks, the Air Pollution Control Division consulted a technical working group and reviewed how other states have established similar values.
The newly adopted standards will be submitted to the Colorado General Assembly in December 2025 as required by law. In addition, the Air Pollution Control Division is seeking public feedback until October 12, 2025 on a related report examining whether a permitting program could use these benchmarks to assess risks and require measures to reduce exposure if authorized by the legislature. The division plans to present both the benchmarks and this report at the January 2026 SMART Act hearings.
The commission will review these benchmarks every five years and may consider adding more pollutants to the list of priority air toxics in future reviews.
More information about each pollutant’s health impacts, sources, and how Colorado calculated these benchmarks can be found in rulemaking hearing materials or on the state’s priority air toxics web page.
