Visibility to Improve at 18 National Parks and Wilderness Areas

The U.S. Environmental Protection Agency is proposing to approve Arizona’s air quality plan to control sulfur dioxide and soot at three power plants in the state. EPA is also proposing additional pollution controls for nitrogen oxide at those plants. These actions will improve visibility and human health at 18 national parks and wilderness areas, including the Grand Canyon, Saguaro National Park and the Petrified Forest.

More than 11 million people visit national parks in Arizona every year. Yet for many visitors the spectacular vistas are veiled in haze, dulling the natural beauty. Ninety percent of the time, the Grand Canyon’s air is impaired by pollution. On average, pollution reduces the Grand Canyon's pristine natural visual range by more than 30 percent.

EPA is proposing to approve Arizona’s plan that controls emissions of sulfur dioxide and coarse particles from the older boilers at three power plants located in eastern Arizona. In addition, EPA is proposing a federal plan to limit nitrogen oxides (NOx) emissions at these same three plants. Specifically, the proposal is designed to cut NOx emissions by 7,800 tons per year at the Cholla Power Plant, 4,700 tons/year at the Apache Generating Station, and 4,500 tons/year at the Coronado Generating Station.

“Visitors to magnificent national parks in Arizona like the Grand Canyon are critical to the state’s economy,” said Jared Blumenfeld, EPA’s Regional Administrator for the Pacific Southwest. “This proposal will make scenic vistas clearer while cleaning the air that Arizonans breathe.”

Under the Clean Air Act, Congress set a long-term goal of restoring natural visibility conditions in numerous national parks and wilderness areas throughout the United States, known as Class 1 Areas. One of the strategies for achieving this goal is the use of Best Available Retrofit Technology at older power plants that cause or contribute to visibility impairment at Class I areas. The three power plants impact 18 of these areas.

In addition to reducing visibility, NOx reacts with other chemicals to form ozone and fine particles, both harmful to the public’s health. Ozone forms when NOx and volatile organic compounds react in the presence of heat and sunlight. Children, the elderly, people with lung diseases such as asthma, and people who work or exercise outside are at risk for adverse effects from ozone and particulate matter.

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