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Updated: Jul 1, 2026
12:44
Watershed Planning within a Quantitative Scenario Analysis Framework
Published on: July 24, 2016
Urban ozone nonattainment: Interconnected challenges in the Intermountain Western U.S.
Ellis S Robinson1,2, Chayan Roychoudhury2, Yousaf Hameed3
1Dept. Of Chemical and Environmental Engineering, University of Arizona, Tucson, Arizona, USA.
Journal of the Air & Waste Management Association (1995)
|June 30, 2026
Summary
Urban ozone levels remain high in four western US cities despite emission cuts. Shared factors like background ozone and terrain effects, plus unique regional issues, hinder progress. Tailored air quality strategies are crucial for these nonattainment areas.
Area of Science:
- Atmospheric Chemistry
- Air Quality Science
- Environmental Policy
Background:
- Four major Intermountain Western U.S. urban areas exceed the 2015 8-hour ozone standard.
- Reductions in anthropogenic precursor emissions have not resolved ozone nonattainment.
Purpose of the Study:
- To synthesize shared and region-specific drivers of persistent urban ozone nonattainment.
- To identify factors limiting the effectiveness of local emission controls in Phoenix, Las Vegas, Wasatch Front, and Denver.
Main Methods:
- Synthesis of recent field campaigns and regulatory analyses.
- Observationally-constrained modeling.
- Case study analysis of four urban nonattainment areas.
Main Results:
- Elevated background ozone, terrain-driven recirculation, and stagnant meteorological conditions are shared challenges.
- Airshed-specific factors include monsoon photochemistry (Phoenix), entrainment (Las Vegas), corridor confinement (Wasatch Front), and complex terrain/oil & gas emissions (Denver).
- These factors reduce the efficacy of local emission control strategies.
Conclusions:
- Persistent ozone nonattainment requires airshed-specific management strategies.
- Coordinated collaborative science is needed to support regulatory decisions.
- Enhanced monitoring and attribution of ozone precursors are essential.
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