CO HB1165

Requires sellers of private residential real property to test for radon hazards prior to sale using Colorado Department of Public Health and Environment-approved procedures, effective January 1, 2013.

Sellers must timely disclose test findings and provide documentation to potential purchasers evidencing test completion and results.

Radon hazard mitigation costs are subject to private negotiation between seller and purchaser; the bill does not require sellers to perform any mitigation.

Establishes "safety level" as radon concentration exceeding 4 picocuries per liter of air (pCi/L), which may be modified by federal or state environmental agencies in the future.

Provides immunity from liability for property owners, authorized agents, and persons in possession of real property for damages resulting from the operation, maintenance, installation, or effectiveness of any mitigation undertaken.