The most recent review of the Environmental Protection Agency’s national ozone standards was a contentious one, with significant advocacy efforts from environmental organizations and industry alike.

If you watched television or listened to a radio in the Washington D.C. area at any point in September 2015, you were likely to encounter industry-funded ads that cautioned of the high costs of changing the standards, which the EPA estimated to cost as much as $1.4 billion in 2025 alone. Ultimately, EPA Administrator Gina McCarthy decided to revise the 2008 ozone standards of 75 parts per billion to a level of 70 ppb, a decision that upset advocates on both sides.

Ozone cars

(Photographer: George Frey/Bloomberg)

As can be expected of any major EPA decision, the ozone standards are now being challenged in federal court, with lawsuits filed by states, industry and environmental groups. Late last week, opening briefs were filed with the U.S. Court of Appeals for the District of Columbia Circuit, outlining various arguments against the EPA’s decision to set the ozone standards at 70 ppb.

Here’s an overview of the main arguments, which the EPA will respond to this summer when it files its response brief with the court.

Industry and States:

The main argument advanced by a coalition of states, led by Arizona, and various industry groups, including the U.S. Chamber of Commerce and the National Association of Manufacturers, focuses on the attainability of the standards. Those parties allege that the EPA unlawfully set the standards at a level that some areas of the country will not be able to meet due to uncontrollable emissions sources, including emissions from Mexico and Asia.

Another argument advanced by the state and industry petitioners is that the EPA’s ozone rule is unlawful because the agency failed to take into account the negative economic, social and energy effects related to lowering the standards. For example, the industry groups argue that while the EPA accounted for positive health benefits related to lowering exposure to ozone, the agency failed to consider negative health consequences associated with job losses that could occur if industrial facilities are forced to close as a result of the tighter standards.

While a 2001 unanimous U.S. Supreme Court decision (Whitman v. American Trucking) bars the EPA from factoring in the cost of compliance in its decision on where to set national ambient air quality standards, the states and industry groups argue that the EPA is still required to consider adverse health effects related to its decision.

The state and industry briefs are available at http://src.bna.com/enZ and http://src.bna.com/el4.

Environmental and Public Health Groups:

The Sierra Club and other environmental and public groups argue that the form of the standards (which measures compliance based on a three-year average of the fourth-highest eight-hour ozone level measured each year) allows for communities to be exposed to unsafe levels multiple times a year. Those groups pointed to a study that showed healthy young people exposed to 72 ppb of ozone suffered decreased lung function and other negative health effects.

The environmental and public health groups also allege that the EPA failed to follow recommendations by a group of independent science advisers and did not adequately justify that decision as required by the law. While the 70 ppb level the EPA chose is within the range recommended by the Clean Air Scientific Advisory Committee in 2014, that panel cautioned the agency of “substantial evidence” of negatively health effects at 70 ppb.

The environmental and public health groups’ brief is available at http://src.bna.com/eme.