Code of Federal Regulations Title 40. Protection of Environment § 40.61.122 Emission standard

Emissions of polonium–210 to the ambient air from all calciners and nodulizing kilns at an elemental phosphorus plant shall not exceed a total of 2 curies a year;  except that compliance with this standard may be conclusively shown if the elemental phosphorus plant:

Alternative operating conditions, which can be shown to achieve an overall removal efficiency for emissions of polonium–210 which is equal to or greater than the efficiency which would be achieved under the operating conditions described in paragraphs (a), (b), and (c) of this section, may be used with prior approval of the Administrator. A facility shall apply for such approval in writing, and the Administrator shall act upon the request within 30 days after receipt of a complete and technically sufficient application.