Arizona gets a pass on air pollution that crosses state lines

US environmental regulators have approved Arizona's plan for controlling fine particulate matter. This means Arizona does not have to make further changes to its rules about air pollution that drifts into other states.

The Clean Air Act requires states to prevent their pollution from harming air quality in neighboring states. This approval means Arizona has convinced US environmental regulators that its current rules are enough. Other states that receive Arizona's pollution will now have to find other ways to address their air quality problems.