The U.S. Environmental Protection Agency proposed Tuesday 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 are reportedly designed to 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 Cholla Power Plant, 4,700 tons/year at the Apache Generating Station and 4,500 tons/year at the Coronado Generating Station.
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.
EPA is soliciting public comments on the proposal through Aug. 31, and will host a public workshop and hearing on Tuesday, July 31, in Phoenix. The deadline for final EPA action is Nov. 15.
For additional information on the proposed rulemaking and opportunities to provide input, go online to http://www.epa.gov/region9/air/actions/az.html#all.