By Amanda Durish Cook

The Environmental Protection Agency last week tightened its ground-level ozone limits to 70 parts per billion (ppb), a less strenuous standard than some electric generators had feared and public health advocates had sought.

The National Ambient Air Quality Standards (NAAQS) rule could impact more than three dozen coal-fired electric generators lacking scrubbers or not using them full time.

In areas expected to need to reduce nitrogen oxides (NO_x) emissions under the rule, EPA’s Regulatory Impact Analysis identified 37 coal-fired generators that either do not have selective catalytic reduction (SCR) systems (30 units, 5.4 GW) or have the scrubbers but do not always use them (seven units, 3.1 GW).

In addition, new generators could be restricted in the more than 350 counties that EPA says will not meet the 70 ppb standard.

Ozone, the main component of smog, aggravates lung diseases, including asthma, emphysema and bronchitis. It forms when emissions of NO_x, volatile organic compounds (VOCs), carbon monoxide and methane are heated by the sun. Utilities, industrial facilities, motor vehicle exhaust, gasoline vapors and chemical solvents are the major man-made sources of NO_x and VOCs.

Industry Reaction

The agency last visited the issue in 2008, when it released a 75 ppb recommendation. EPA was considering a range between 65 and 70 ppb for an eight-hour average.

The Edison Electric Institute had pushed for a new standard at the top end of the range. “While compliance challenges remain with the new standard at 70 ppb, EPA has recognized the serious implementation concerns raised by stakeholders of setting the standard below 70 ppb,” EEI President Tom Kuhn said in a statement.

The ozone standard doesn’t directly apply to power producers but to their states. David Flannery, legal counsel for the Midwest Ozone Group, said that it’s “too early to tell” how either will be affected. The group represents coal-burning utilities including American Electric Power, Duke Energy and Ameren.

“States will have to decide how they’re going to apply this ambient air standard,” Flannery said. “There’s a mix of sources that contribute. This includes cars and mobile sources in addition to the industrial sources.”

Flannery said that states are still planning how to meet 2008’s 75 ppb rule. “Part of the criticism of the new standard is that the EPA introduced the new standard before the old one could be fully implemented,” he said.

Implementation

EPA said it is tightening the standard based on more than 1,000 recent studies that suggested the current limit did not adequately protect public health.

Assuming it survives anticipated legal challenges, the next step in enforcing the ruling is to designate attainment and nonattainment areas. States will have to suggest designation areas within a year; EPA will make designations by October 2017 using air quality data from 2014 to 2016.

States identified with nonattainment areas will be forced to devise emission inventories and establish a preconstruction permitting program. The preconstruction permits apply to “new or expanding sources of air pollution,” including power plants, industrial boilers and factories.

Any state containing nonattainment areas sorted into the “moderate” or higher category will have until 2021 to design state implementation plans demonstrating the pollution-reducing steps they will take to comply. Deadlines for compliance from nonattainment areas will range from 2020 to 2037.

The agency estimated the new standard will cost $1.4 billion while producing health benefits of $2.9 billion to $5.9 billion.

It says compliance with the new threshold will be made easier by existing environmental rules, including emission control requirements for motor fuels and vehicles, the Mercury and Air Toxics Standards (MATS) and the carbon emission reductions under the Clean Power Plan.

‘Missed Opportunity’

EPA says average ozone levels have dropped 33% nationally since 1980 and that more than 90% of areas designated nonattainment for the 1997 ozone standards now meet those standards. EEI says the electric power sector has reduced sulfur dioxide (SO₂) emissions by 80% and NO_x by almost three-quarters since 1990 despite increased power demand.

Michael Brune, executive director of environmental advocate Sierra Club, called the rule “a modest step” and “a missed opportunity.”

“Over the past seven years, medical scientists have been clear that any standard above 60 ppb puts our communities at risk and is especially dangerous to children, seniors and people with respiratory illnesses,” Brune said in a statement.