National Emission Standard for Hazardous Air Pollutants; National Emission Standards for Radon Emissions From Phosphogypsum Stacks

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This document contains a correcting amendment to the final regulations for the National Emission Standard for Radon Emissions from Phosphogypsum Stacks, 40 CFR Part 61, Subpart R, which were originally published Wednesday, February 3, 1999 (64 FR 5574). This final rule promulgated revisions to the National Emission Standard for Hazardous Air Pollutants (NESHAP) that set limits on radon emissions from phosphogypsum stacks; and raised the limit on the quantity of phosphogypsum that may be used in indoor laboratory research and development from 700 to 7,000 pounds per experiment, eliminating current sampling requirements for phosphogypsum used in indoor research and development, and clarifying sampling procedures for phosphogypsum removed from stacks for other purposes.