The Illinois Radon Awareness Act requires:

The Act does not require all homes to be tested for radon — testing is entirely voluntary and is left to the discretion of the buyer, who may choose to conduct radon testing as part of their due diligence after receiving the disclosure pamphlet.

The Act places no financial obligation on buyers to pay for radon mitigation — mitigation costs are a negotiable item between buyer and seller, and the statute is silent on who bears mitigation costs, leaving it entirely to contract negotiation.

The 4.0 pCi/L figure is the EPA's action level guideline recommending mitigation when radon levels exceed this threshold, but it is not a legal requirement under the Illinois Radon Awareness Act — the Act does not mandate that any specific radon level be achieved before a property can be sold.