; (iii) modifying 60.482–6a of title 40, Code of Federal Regulations (as in effect on the date of enactment of this Act), to ensure that the use of open-ended valves or lines is prohibited except if a showing is made that the use of an open-ended valve or line is necessary for safety reasons; and (iv) modifying subpart VVa of part 60 of title 40, Code of Federal Regulations (as in effect on the date of enactment of this Act), to ensure that— (I) the term no detectable emissions is defined to mean an instrument reading of less than 50 parts per million above background concentrations; and (II) the term leak is defined to mean an instrument reading of greater than or equal to 50 parts per million above background concentrations. (F) Natural-gas fired steam boilers Not later than 3 years after the date of enactment of this Act, the Administrator shall promulgate a final rule revising subpart Db of part 60 of title 40, Code of Federal Regulations (as in effect on the date of enactment of this Act), to ensure that boilers or heaters located at an affected covered facility regulated under that subpart may only burn gaseous fuels, not solid fuels or liquid fuels. (G) Monitoring Not later than 3 years after the date of enactment of this Act, the Administrator shall promulgate a final rule revising subparts DDD, NNN, RRR, and other relevant subparts of part 60 of title 40, Code of Federal Regulations (as in effect on the date of enactment of this Act)— (i) to require continuous emissions monitoring of nitrogen oxides, sulfur dioxide, carbon monoxide, and filterable particulate matter for all combustion devices except for non-enclosed flares, including during startups, shutdowns, and malfunctions of the facilities regulated by those subparts; (ii) to require— (I) accurate and continuous recordkeeping when continuous monitoring is required under clause (i); and (II) the records required under subclause (I) to be made available to the public