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EPA Issues a New, Lower Ozone Standard That Will Prove to Be a Challenge to Many States

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By Chris Colyer

On October 1, 2015, the United States Environmental Protection Agency (EPA) issued a final rule reducing its National Ambient Air Quality Standard (NAAQS) for ozone from 75 parts per billion (ppb) to 70 ppb. This new standard could have far-reaching impacts on states, particularly Arizona, which have limited options to further reduce their ozone pollutant levels.

Pursuant to the federal Clean Air Act, EPA periodically sets standards for the allowable concentrations of common air pollutants in the ambient air. These standards, known as NAAQS, take into account the risk to public health presented by elevated levels of air pollutants. Every state is responsible for ensuring that the quality of ambient air in its jurisdiction attains and maintains these EPA-established NAAQS.

EPA argues the new 70 ppb ozone standard will provide increased public health protection for children, older adults, and people with lung diseases, resulting in estimated net economic health benefits of $2.9 to $5.9 billion nationwide by 2025. EPA estimates the annual cost of compliance with the new standard will be $1.4 billion.

Once the new rule is published, states will have one year (i.e., the fall of 2017) to issue recommendations to EPA as to whether it can meet the new revised standard. EPA will then issue determinations of whether the states can attain the revised standards during the following year, using air quality data from the previous three years. For those areas that EPA designates as not attaining the new 70 ppb standard, the states will have three years to submit a “state implementation plan” that describes the initiatives and controls that will be implemented to attain the new standard.

The implications of the new ozone NAAQS will be severe for some states, particularly Arizona. The Arizona Department of Environmental Quality (ADEQ) estimates that nine of the ten Arizona counties that currently measure ozone will be unable to meet the new 70 ppb standard. However, Arizona will have very limited options to reduce its current ozone levels as Arizona’s primary source of ozone pollution is not from industry. Instead, the primary causes of ozone in Arizona are vehicles and international sources such as Mexico and China. Arizona lacks the ability to require reductions in vehicle emissions, and likewise, lacks authority to reduce emissions from international sources. ADEQ predicts that the impact of the new NAAQS will be particularly severe on Arizona’s rural counties, such as La Paz County, which has only 20,000 people, is the size of Connecticut, and has no other local ozone control options. In fact, ADEQ asserts that to ensure air quality improvement, it will have to require new/modified sources of air pollution to somehow remove or offset more ozone from the air than the new/modified source can itself emit.

EPA states it will propose additional guidance to assist states in meeting the new ozone NAAQS. EPA also asserts that additional existing and proposed rules—including the Clean Power Plan, Tier 3 Vehicle Emissions and Fuels Standards, and the Mercury and Air Toxics Standards—will help further reduce ozone-forming pollution so that areas can attain the new 70 ppb standard in the future.

We will continue to monitor the potential impacts of the new ozone NAAQS and provide periodic blog updates once EPA issues its proposed guidance regarding attainment of the new standard.