Haze is composed of tiny airborne particles, called “particulate matter,” and gases, including nitrogen oxides and sulfides, that reflect light, reducing visibility and endangering public health. Sources of haze include coal-fired power plants, oil and gas operations, and vehicles.
The Environmental Protection Agency’s (EPA) 1999 Regional Haze Rule protects clean air for visibility in national park and wilderness areas, as well as for public health. The rule requires emissions controls on coal-fired power plants known as “best available retrofit technology,” or BART. These controls limit pollutants that reduce visibility by forming regional haze. The rule also requires states to submit plans and progress reports for reducing haze.
In April 2016 the EPA released proposed updates to the Regional Haze Rule to strengthen it and extend requirements through 2028. Learn more about how partner groups are involved.
NATIONAL PARK SERVICE PHOTOS
Big Bend National Park, Texas on non-hazy and hazy days.