The Regional Haze Rule (RHR) calls for state and federal agencies to work together to improve visibility across the 156 national parks and wilderness areas listed in the rule. RHR calls for states to establish goals and emission reduction strategies for improving visibility in mandatory Class I Federal areas including required actions when submitting regional haze state implementation plans (SIPs) and progress reports. Plans must demonstrate how states have made, and will continue to make progress toward achieving their visibility improvement goals. The first state plans were due in 2007 and covered 2008-2018, referred to as the first planning period. The 2017 RHR revisions gave a one-time extension to the planning period lasting until 2021. Comprehensive periodic revisions to these initial plans are currently due in 2021, 2028, and every 10 years thereafter.

Recently the U.S. Environmental Protection Agency (EPA) announced its decision to revisit aspects of the 2017 Regional Haze Rule revisions. EPA intends to commence a notice-and-comment rulemaking in which EPA will address portions of the rule, including but not limited to, the Reasonably Attributable Visibility Impairment (RAVI) provisions and the provisions regarding Federal Land Manager (FLM) consultation. Furthermore, EPA plans to finalize one or more EPA guidance documents for regional haze SIP revisions due in 2021.

EPA intends to prepare a notice of proposed rulemaking that will provide the petitioners and the public an opportunity to comment on the issues identified above, as well as any other aspects of the rule they believe will benefit from further public input. For more information on this decision visit the EPA site here and look for EPA's proposal in coming months.