# Colorado — State Residential Radon Disclosure, Testing, and Certification Requirements

For Colorado, disclosure required is Yes; sellers must provide buyers a state-developed radon pamphlet and disclose in writing any knowledge of radon concentrations, radon testing, or radon mitigation systems at the property. Landlords must also provide radon disclosure before lease signing; testing mandated is Yes; schools must test for radon in accordance with AARST protocols. Newly constructed schools must test within 19 months of occupancy. Child care facilities must test within six months of occupancy; professional certification required is Yes; state license required for individuals performing radon mitigation or radon measurement; action level pci l is 4 pCi/L; school testing required is Yes; schools must test for radon in accordance with 2015 AARST Protocols and maintain results on file. Child care facilities must also test, recorded from its source on 2026-08-15.

- **jurisdiction:** Colorado
- **disclosure required:** Yes; sellers must provide buyers a state-developed radon pamphlet and disclose in writing any knowledge of radon concentrations, radon testing, or radon mitigation systems at the property. Landlords must also provide radon disclosure before lease signing.
- **testing mandated:** Yes; schools must test for radon in accordance with AARST protocols. Newly constructed schools must test within 19 months of occupancy. Child care facilities must test within six months of occupancy.
- **professional certification required:** Yes; state license required for individuals performing radon mitigation or radon measurement
- **action level pci l:** 4 pCi/L
- **school testing required:** Yes; schools must test for radon in accordance with 2015 AARST Protocols and maintain results on file. Child care facilities must also test.
- **statute citation:** Colorado Revised Statutes §§ 38-35.7-112, 38-12-803, 12-165-101--113, 25-1.5-101

## What the source says

> Requires sellers to provide buyers a state-developed radon pamphlet and to disclose in writing any knowledge of radon concentrations, radon testing, or radon mitigation systems at the property

## Source

- https://www.eli.org/sites/default/files/files-pdf/2025%20Radon.pdf

Last verified: 2026-08-15. Review by: 2027-08-15.
Part of [State Residential Radon Disclosure, Testing, and Certification Requirements](https://referencesource.org/state-radon-disclosure-requirements/).