U.S. Environmental Protection Agency Region 1 5 Post Office Square Suite 100 Boston, MA 02109-3912 Electronic Filing via Regulations.gov Re: Comments on Proposed Approval and Promulgation of Air Quality Implementation Plans; Massachusetts; Regional Haze State Implementation Plan for the Second Implementation Period [EPA Docket No. EPA–R01–OAR–2023–0185] The National Parks Conservation Association, Sierra Club, Appalachian