[Code of Federal Regulations] [Title 40, Volume 8] [Revised as of July 1, 2007] From the U.S. Government Printing Office via GPO Access [CITE: 40CFR61.202] [Page 146] TITLE 40--PROTECTION OF ENVIRONMENT CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PART 61_NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS --Table of Contents Subpart R_National Emission Standards for Radon Emissions From Phosphogypsum Stacks Sec. 61.202 Standard. Each person who generates phosphogypsum shall place all phosphogypsum in stacks. Phosphogypsum may be removed from a phosphogypsum stack only as expressly provided by this subpart. After a phosphogypsum stack has become an inactive stack, the owner or operator shall assure that the stack does not emit more than 20 pCi/(m\2\-sec) (1.9 pCi/(ft\2\-sec)) of radon-222 into the air. [57 FR 23317, June 3, 1992, as amended at 65 FR 62158, Oct. 17, 2000]