In response to a court order, the U.S. Environmental Protection Agency (EPA) on Friday finalized an update to its national air quality standards for harmful fine particle pollution (PM2.5), including soot, setting the annual health standard at 12 micrograms per cubic meter. By 2020, ninety-nine percent of U.S. counties are projected to meet revised health standard without any additional actions.

The announcement has no effect on the existing daily standard for fine particles or the existing daily standard for coarse particles (PM10), which includes dust from farms and other sources), both of which remain unchanged.

“These standards are fulfilling the promise of the Clean Air Act. We will save lives and reduce the burden of illness in our communities, and families across the country will benefit from the simple fact of being able to breathe cleaner air,” said EPA Administrator Lisa Jackson.

Fine particle pollution can penetrate deep into the lungs and has been linked to a wide range of serious health effects, including premature death, heart attacks, and strokes, as well as acute bronchitis and aggravated asthma among children, according to EPA.