On March 16, 2015, the EPA published a final rule that made revisions to the New Source Performance Standards (NSPS) for new residential wood heaters (80 FR 13672) ("the 2015 rule"). The 2015 rule updated the 1988 NSPS to reflect significant advancements in wood heater technologies and design, broadened the range of residential wood-heating appliances covered by the regulation, and improved and streamlined implementation procedures. On November 30, 2018, the EPA published a Notice of Proposed Rulemaking (NPRM) to amend the 2015 rule, requesting comment on whether the minimum pellet fuel requirements should be retained and, if so, whether they should be revised (83 FR 61574). Also on November 30, 2018, EPA published an Advance Notice of Proposed Rulemaking (ANPRM) to solicit comment on several aspects of the 2015 final rule (83 FR 61585). On April 2, 2020, the EPA finalized the NPRM that was proposed on November 30, 2018, (85 FR 18448). The final rule addressed minimum pellet requirements and other issues identified in the NPRM. Regulatory development for the next iteration of the NSPS will proceed once the new emission test methods have been promulgated for wood heaters. A consent decree was entered with the court that established a proposal date of December 15, 2026, for subpart AAA and a promulgation date of December 15, 2027. For QQQQ, a proposal date of December 15, 2027, and a promulgation date of December 15, 2028, were agreed to for completion of review.