EPA Rules Against Penalizing Phoenix Area for Outside Pollution

The region will remain a 'moderate' nonattainment zone despite ongoing efforts to improve air quality.

Apr. 1, 2026 at 3:54pm

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The Environmental Protection Agency has ruled that the Phoenix metropolitan area should be excluded from stricter air quality standards, acknowledging that a significant portion of the region's ozone pollution is caused by sources outside of local control, such as pollution from other states and Mexico as well as wildfires. This decision will prevent the area from receiving a 'serious' nonattainment label that could have added additional regulatory burdens on businesses.

Why it matters

The EPA's decision recognizes the unique geographic and cross-border challenges the Phoenix area faces in meeting federal air quality standards, and avoids potential economic harm that could have resulted from a 'serious' nonattainment designation. This ruling allows the region to continue its efforts to improve local pollution sources while not being penalized for external factors beyond its control.

The details

Since 2023, Phoenix area leaders have argued that most of the ozone pollution contributing to poor air quality in the region is caused by pollution coming in from other states and Mexico. The mountains around the Valley create a 'bowl' effect that traps heavier, polluted air. Despite the area reducing air pollution by 70% since 1990, pollution crossing the border has prevented the region from going below federal minimums. The EPA's ruling acknowledges that 80% of the ozone impacting the area comes from international sources and wildfires that lie beyond the area's capabilities to control.

  • Since 2023, Phoenix area leaders have argued that most of the ozone pollution is from outside the region.
  • In March 2023, the EPA visited Phoenix to discuss the area's air quality classification.
  • On March 23, 2026, the EPA ruled the Phoenix region should be excluded from stricter air quality standards.

The players

Environmental Protection Agency

The federal agency responsible for setting and enforcing air quality standards under the Clean Air Act.

Lee Zeldin

The EPA Administrator who visited Phoenix in 2023 to discuss the area's air quality classification.

Danny Seiden

The President and CEO of the Arizona Chamber of Commerce & Industry, who stated that 80% of the ozone impacting the Phoenix area comes from international sources and wildfires.

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What they’re saying

“80% of the ozone impacting the area comes from international sources and wildfires that lie beyond the area's capabilities to control.”

— Danny Seiden, President and CEO, Arizona Chamber of Commerce & Industry

What’s next

The EPA's ruling will allow the Phoenix metropolitan area to continue its efforts to improve local pollution sources without the added regulatory burdens of a 'serious' nonattainment designation.

The takeaway

The EPA's decision recognizes the unique geographic and cross-border challenges the Phoenix area faces in meeting federal air quality standards, and avoids potential economic harm that could have resulted from a stricter nonattainment designation. This ruling allows the region to focus on improving local pollution sources while not being penalized for external factors beyond its control.