The 1977 Amendments to the Clean Air Act (CAA) set a national goal to restore the 156 federally mandated Class 1 Areas to pristine conditions by preventing any future, and remedying any existing, man-made visibility impairment, or “regional haze”.
Protection of visibility impairment from new sources was established in a 1980 rulemaking where requirements for visibility impairment in terms of “reasonably attributable” impairment and regional haze were addressed. Regulations specifically targeting visibility impairment in Class 1 Areas were finalized in the 1999 Regional Haze Rule (RHR). Over the course of the past two decades these regulations have evolved:
- July 1, 1999 - EPA promulgated the RHR to address regional haze. As part of the RHR, it established applicability criteria for defining Best Available Retrofit Technology (BART) eligible sources. States were also required to developed regional haze State Implementation Plans (SIPs) to establish a uniform rate of progress (URP) or “glidepath” for each Class I area, reasonable progress goals (RPGs), and long term strategies (LTS) for attaining natural visibility conditions by 2064.
- July 6, 2005 - Amendments to the 1999 RHR were finalized. These amendments (often called the BART rule) applied to the provisions of the RHR that require BART emission controls and included definitions for BART applicability criteria and guidance for making source-specific BART determinations.
- 2007-2018 - States completed source-specific BART determinations with SIPs due to EPA in 2007 describing the strategy for achieving RPGs through 2018. There are still pending BART analyses in various states that are undergoing litigation; however, the end of the 1st planning period, and BART, occurred on December 31, 2018.
- July 8, 2016 - EPA issued draft guidance for states in the development of their regional haze SIPs and progress reports for the 2nd planning period (2018-2028).
- January 10, 2017 - EPA finalized revisions to the RHR including clarifying a state's LTS and RPGs for SIPs, finalizing the requirement to select the 20% most impaired days from anthropogenic sources, and allowing the adjustment to URPs for international anthropogenic impacts.
- September 11, 2018 - EPA released the Regional Haze Reform Roadmap outlining a path for EPA to work collaboratively with states to implement the RHR including converting any remaining BART FIPs to SIPs.
- December 20, 2018 - Technical Guidance issued for the 2nd planning period. Details on this Guidance and strategies for industrial sites are provided in the next section.