15 U.S. Code § 2663 - EPA citizen’s guide
In order to make continuous progress toward the long-term goal established in section 2661 of this title, the Administrator of the Environmental Protection Agency shall, not later than June 1, 1989, publish and make available to the public an updated version of its document titled “A Citizen’s Guide to Radon”. The Administrator shall revise and republish the guide as necessary thereafter.
The updated citizen’s guide published as provided in subsection (a) shall include a description of a series of action levels indicating the health risk associated with different levels of radon exposure.
 So in original. Probably should be “action”.
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