The map below illustrates the current implementation of laws in the U.S supporting actions against radon in homes. To clarify the differences, the degree of regulation is presented in a four-color code. The most protection by the regulation with current laws is colored green. The worst case is white, which means no regulation in addition to the federal recommendation of 150 Bq/m³ (= 4 pCi / l). Source: Environmental Law Institute
 

 White   = No Regulation, just the federal recommendation.

 Blue     = Only Support to Homebuyers with Construction regulation or Real estate forms.

 Cyan    = In addition, Promotion of Radon professionals with Proficiency list or Certified service.

 Green   = Second addition, Promoted Radon Mitigation funds or screening results reported.