Requires a seller of real property containing up to four units to complete a disclosure report form, on which the seller must report if he/she is aware of various environmental conditions, including unsafe concentrations of radon and unsafe conditions relating to asbestos or lead paint on the premises.

Authorizes the state to undertake a variety of radon-related activities, including radon measurement, surveys, monitoring, education, and technical assistance. Requires the licensing of persons selling radon detection devices, performing radon detection, or performing radon reduction services. Also requires state approval of radon sampling and measurement devices that are sold to a radon contractor for use in licensed activities. Authorizes the state to establish minimum qualifications for licensure. Requires persons testing for radon to report results of testing within 45 days. Regulations adopted under the law (Ill. Admin. Code, tit. 32, Pt. 422) establish procedures and requirements for obtaining a license as a radon mitigator or tester, and set forth protocols for radon measurement and mitigation. Regulations include licensing provisions for measurement and mitigation of multi-family buildings of three stories or less.