Following through on a proposal it made last year, the Environmental Protection Agency (EPA) has strengthened the National Ambient Air Quality Standards (NAAQS) for ground-level ozone to 70 parts per billion (ppb) from 75 ppb.

The change, which was “based on extensive scientific evidence on effects that ground-level ozone pollution, or smog, has on public health and welfare,” will improve public health protection, particularly for at risk groups including children, older adults, and people of all ages who have lung diseases such as asthma,” EPA said Thursday. Ground-level ozone forms when nitrogen oxides and volatile organic compounds react in the air.

But the new standard isn’t needed, according to Sen. Jim Inhofe (R-OK), chairman of the Senate Environment and Public Works Committee.

“EPA’s decision to restrict the ozone standard to 70 ppb is yet another example of the Obama administration’s enthusiasm for needless regulation,” Inhofe said. “Since 1980, we have cut ozone-forming emissions by half, and the trend would have continued without setting a new standard. This progress is even clear in my state of Oklahoma, which will remain in attainment under the new standard.”

EPA released its proposal to tighten the NAAQS for ozone in late November, raising the ire of industry, regulators and Republicans who were poised to take control of Congress (see Daily GPI, Nov. 26, 2014). In a 626-page report released at that time, the agency proposed lowering the primary and secondary standards for ozone for power plants and factories from fossil fuel burning from 75 ppb to a range of 65-70 ppb. Under the federal Clean Air Act, the agency is required to review the standards every five years; it was last set to 75 ppb in 2008.

EPA is also strengthening the secondary ozone standard to 70 ppb and is extending the ozone monitoring season for 32 states and the District of Columbia.

EPA said it examined nearly 2,300 studies in its review of the ozone standards, including more than 1,000 studies published since the 2008 review of the standards. “Scientific evidence shows that ozone can cause a number of harmful effects on the respiratory system, including difficulty breathing and inflammation of the airways.

“The revised standards will significantly improve public health protection, resulting in fewer premature deaths, and thousands fewer missed school and work days and asthma attacks…Evidence also indicates that long-term exposure to ozone is likely to be one of many causes of asthma development. And studies show that ozone exposure is likely to cause premature death. The public health benefits of the updated standards, estimated at $2.9 to $5.9 billion annually in 2025, outweigh the estimated annual costs of $1.4 billion,” EPA said.

The Clean Air Act provides states with time to meet the standards. Depending on the severity of their ozone problem, areas would have until between 2020 and 2037 to meet the standards.

Local communities, states and the federal government have made substantial progress in reducing ground-level ozone, according to EPA. From 1980 to 2014, average ozone levels nationally fell 33%, even as the economy and population continued to grow.

EPA’s rule “is clearly a step in the wrong direction,” said Frank Macchiarola, executive vice president for America’s Natural Gas Alliance.

“Today’s ozone rule comes at a time when we are experiencing a renaissance in the manufacturing sector, thanks in part to clean and affordable natural gas,” Macchiarola said. “The rule threatens the economic progress our nation is making in the manufacturing sector and will create a regulatory burden that will make compliance in some regions, near impossible. Additionally, it will add to the uncertainty facing oil and gas producers and could dampen investment by the industry in our domestic energy abundance. It is clearly a step in the wrong direction.”

But according to the Union of Concerned Scientists (UCS), the EPA ozone standard is overdue and EPA could have gone even further to protect the public.

“Since 1997, the EPA’s panel of external experts, the Clean Air Scientific Advisory Committee, has recommended an ambient ozone standard of at most 70 ppb,” said Gretchen Goldman, lead analyst at UCS. “The EPA chose to set the standard here — the most lenient rule possible given the agency’s responsibilities to set the standard at a level that protects public health. It is commendable that the EPA is finally following the advice of its science advisors, after years of delay in tightening the outdated standard. However, the scientific evidence suggests that this standard might not be strong enough.”

Jack Gerard, CEO of the American Petroleum Institute, called on Congress to move legislation to slow EPA’s regulation of ozone.

“Current ozone standards protect public health without further stifling jobs or harming our economy,” Gerard said. “Our nation’s air is getting cleaner as we implement the existing standards, but the administration ignored science by changing the standards before allowing current standards to work. It’s time for Congress to step in and block this unnecessary and costly regulation to protect American consumers.”

Inhofe vowed to pursue such legislation in his committee.

“Our country should have been given the opportunity to fully meet the 2008 standard before implementing another frivolous and costly mandate,” Inhofe said.