Four Pennsylvania coal plants must cut nitrogen oxide emissions to meet 2008 air standards

US environmental regulators are forcing four coal-fired power plants in Pennsylvania to reduce their nitrogen oxide emissions. This means the plants must use specific pollution control technology to meet air quality standards set in 1997 and 2008.

For years, these coal plants operated under less strict rules, even as air quality standards tightened. This decision means they can no longer delay upgrading their pollution controls. It forces them to adopt technology that has been available for decades, bringing them into compliance with older, but still relevant, clean air laws.