Paul Atkinson/KJZZ

Phoenix, Arizona.

The 9th Circuit Court of Appeals has ruled the federal Environmental Protection Agency was right to accept Arizona’s plan to reduce its air pollution, specifically larger particulate matter such as dust known as PM-10.

The plan aimed to reduce PM-10 emissions by at least 5 percent over a five-year period, but the so-called “5 Percent Plan” also didn’t include more than 130 “exceptional events,” where those emissions exceeded air quality standards. Examples of exceptional events could be dust storms or monsoon activity.

"This was excessive because the bottom line is the air is unhealthful," said Sandy Bahr, one of the plaintiffs challenging the EPA’s acceptance of the plan. Bahr is also director of the Grand Canyon chapter of the Sierra Club.