Four of those parks are in Colorado: Great Sand Dunes National Park, Rocky Mountain National Park, Black Canyon Of The Gunnison National Park and Mesa Verde National Park all at some point experience "moderate" ozone levels according the EPA's Air Quality Index. That means the ozone hovers near and periodically exceeds a federal safety standard for ozone.
The Denver Post dug deeper into the numbers, finding average ozone levels in the parks are only slightly lower than the health standard for sensitive groups. Vistas in Colorado national parks have also suffered from the poor air quality, where haze cut visibility by 38 to 55 miles.
The Regional Haze Rule within the Clean Air Act sets a standard that national parks should have the cleanest air and promises pollution-free air by 2064. That rule has been key for environmentalists working to clean up Colorado's national parks. Last year, the NCPA and environmental nonprofit WildEarth Guardians resolved an appeal against Tri-State Generation and Transmission. Tri-State agreed to install pollution controls on one of its older coal-fired units at Craig Station to cut nitrogen oxides clouding up Rocky Mountain National Park.
The NCPA now wants the Obama Administration to up its enforcement of the Regional Haze Rule by closing loopholes and setting park-centered targets. "By making these changes," write the authors, "President Obama can put our national parks on the path to clean air within the next decade."
Still, it should be noted that Colorado's parks weren't the worst batch it the report. That title falls to California, where four national parks earned the lowest grade for air quality. Ozone levels are regularly unsafe in Yosemite, Joshua Tree, Kings Canyon and Sequoia National Parks.
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