On August 4, 2020, EPA Principal Deputy Assistant Administrator for Air Anne Austin released the final “Guidance on Plantwide Applicability Limitation Provisions Under the New Source Review Regulations” (PAL Guidance), which finalizes the draft released on February 19, 2020 (discussed in NSR Law Blog). The PAL Guidance addresses concerns about when EPA or state permitting authorities should use the mandatory and discretionary permit reopening and provides additional guidance on PAL expiration and termination, the so-called PAL “ratchet” upon renewal, monitoring and data substitution, and calculation of baseline actual emissions for replacement units. The PAL Guidance also provides some example PAL contribution and distribution calculations. Finally, the PAL Guidance addresses input received from regional offices and the public from the February 2020 draft.