Maricopa County must fix its air pollution rules, US environmental regulators say

US environmental regulators have told Maricopa County, Arizona, that its rules for controlling air pollution from gasoline and other liquid fuels are not strong enough. This means the county must update its local regulations to meet federal clean air standards.

For years, local governments have had some flexibility in how they meet federal clean air standards. This decision means that flexibility is shrinking, at least for Maricopa County. It forces the county to tighten its rules on specific industrial emissions, which will likely increase costs for businesses that handle these liquids.