The Arizona Chamber of Commerce & Industry celebrated a major victory for the state’s business community after the EPA approved Arizona’s Clean Air Act Section 179B ozone demonstration.
The ruling confirms that the Phoenix-Mesa region would have met federal air quality standards but for pollution drifting in from international sources and wildfires, factors entirely outside Arizona’s control. As a result, the region will not face a reclassification to a more stringent “Serious” nonattainment designation, sparing Arizona businesses from a wave of costly new regulatory requirements.
“For decades, Arizona’s businesses have done everything right. They’ve invested in cleaner operations, embraced new technology, and helped cut the region’s air pollution by roughly 70 percent since 1990, all while our economy and population grew dramatically. Today’s ruling is a recognition of that work, and a long-overdue acknowledgment that Arizona cannot be held responsible for pollution blowing across our borders from other countries.”
Said Danny Seiden, president and CEO of The Arizona Chamber of Commerce & Industry:
“The science has always been on our side. Independent modeling shows that roughly 80 percent of the ozone impacting the Phoenix area originates outside our region, from international sources and wildfires that no local regulation can touch. Punishing Arizona employers for that pollution would have been illogical and counterproductive, costing jobs and investment without making our air any cleaner.
“We’re grateful to EPA Administrator Zeldin, the Maricopa Association of Governments, ADEQ, Sens. Kelly and Gallego, and Gov. Hobbs for their partnership and shared commitment to commonsense environmental policy.
“The Chamber fought hard for this outcome because our members deserve environmental policy that is grounded in facts, and we stand ready to vigorously defend this decision against any effort to undo it.
The Phoenix-Mesa region has long faced a unique air quality challenge: ozone levels that exceed federal standards due largely to pollution transported from outside U.S. borders, compounded by wildfire smoke. Arizona businesses have invested heavily in local emissions reductions for more than three decades, but modeling has consistently shown that further local controls have little ability to move the needle.
Section 179B of the Clean Air Act provides a mechanism for states in exactly this situation, allowing them to demonstrate that a region would have met air quality standards but for emissions originating outside the United States. The Maricopa Association of Governments submitted that demonstration to the EPA in September 2025. The Arizona Chamber formally supported the proposal and urged EPA to finalize it.
