PM2.5 Precursor Demonstration Guidance
On May 30, 2019, the EPA finalized the PM2.5 Precursor Demonstration Guidance. This guidance is designed to assist air agencies who may wish to develop optional PM2.5 precursor demonstrations as permitted by the PM2.5 State Implementation Plan Requirements Rule (81 FR 58009). In November 2016, EPA released a draft version of this guidance for public review and comment. After considering the comments, EPA made changes which are reflected in this final version of the guidance.