Regional Haze Rule

The Environmental & Energy Law Program is tracking the environmental regulatory rollbacks of the Trump administration. Click here for the list of rules we are followingIf you’re a reporter and would like to speak with an expert on this rule please email us

Shenandoah Valley on hazy and clear days.

Why It Matters

Haze occurs when small particles of air pollution scatter and absorb sunlight, blurring scenic views and decreasing the distance that can be seen from overlooks. In response to this problem, Congress enacted Section 169A of the Clean Air Act to protect visibility in national parks and wilderness areas. The Environmental Protection Agency (EPA) subsequently promulgated the Regional Haze Rule in 1999. The program directs states to implement pollution control plans to improve visibility and air quality at national parks, such as the Grand Canyon. Since the implementation of the regional haze program, the average visual range has increased from 90 to 120 miles in some western parks and from 50 to 70 miles in some eastern parks.

In addition to the benefits for visitors at national parks, the regional haze program delivers public health benefits. The primary pollutants that cause regional haze, including particulate matter,  nitrogen oxides (NOx), sulfur dioxide (SO2), and volatile organic compounds (VOCs), are linked to serious health effects including premature death. Some of these pollutants also contribute to acid rain. Implementation of the Regional Haze Rule and associated regulations has produced sharp declines in the emissions of those pollutants, resulting in improved air quality as well as improved visibility in scenic areas. In fact, EPA estimates that during the first implementation period (2007-2018), there was a reduction in SO2 emissions of 500,000 tons per year and in NOx emissions of 300,000 tons per year.

Current Status

EPA is reviewing certain aspects of a final rule promulgated in 2016 that is intended to ensure that states continue to make progress towards long-term visibility goals. Litigation challenging the final rule is pending in the U.S. Court of Appeals for the D.C. Circuit and has been held in abeyance while EPA completes its review.

On April 12, 2018, President Trump directed the Administrator of EPA, Scott Pruitt, to review EPA’s engagement with states as part of the regional haze program.

On September 10, 2018, Acting Administrator of the EPA Andrew Wheeler announced EPA’s new Regional Haze Reform Roadmap. The Roadmap prioritizes giving more power to the states to determine emissions controls and relying on other Clean Air Act programs to improve visibility. A memo to staff indicated that EPA is developing a rulemaking to modify portions of the Regional Haze Rule.

EPA is also involved in ongoing litigation regarding the adequacy of multiple state plans. For more information on these lawsuits, visit the post on the Regional Haze State Implementation Plans.

Click here learn more about the history of this rule and actions that have been taken on it by the Trump Administration.

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