EPA has revised its regulations guiding the preparation of state implementation plans (SIPs). These regulations are found in 40 CFR Part 51. This action revises the minimum reporting frequency requirement for SIPs applicable to source categories listed in Appendix P to 40 CFR Part 51 from quarterly to semiannual. This is generally consistent with the current reporting frequency requirements to which these sources are subject under other programs (e.g., New Source Performance Standards). Each state can—but is not be required to—revise its SIP to allow semiannual reporting for four source categories:

Read more > https://www.epa.gov/air-quality-implementation-plans/revisions-appendix-p-40-cfr-part-51-concerning-minimum-emission