Power plants across Pennsylvania may get new rules soon to better manage smog-causing pollutants.

The proposed RACT rules -- for Reasonably Available Control Technology -- are ready for public comment, and the state is holding three public hearings. The Southeast Pennsylvania meeting will take place in  the DEP office Norristown on May 28.

The regulations are a federal requirement because Philadelphia and 16 other counties have not met air-quality standards set by the Clean Air Act.

The proposed regulations would further control nitrogen oxides and volatile organic compounds. Those two pollutants are sometimes called NOx and VOCs. The emissions mix with sunlight to form smog (ground-level ozone) and make the air less healthy.

Smog is often a trigger for unhealthy air-alert days

In an email, a Department of Environmental Protection spokeswoman said under the new rules certain Pennsylvania companies will have to change the way they do business.

"Significant collateral NOx emission reductions will be realized," wrote Morgan Wagner.

"It's asking them to meet a limit that's more stringent than previously specified limits," said Vince Brisini, the deputy secretary for the DEP's office of waste, air, radiation and remediation.

The proposed rules would apply to power plants, industrial boilers, steel mills and other large facilities that spew substantial amounts of NOx and VOCs into the air.

While they may be tougher than before, Kim Teplitzky with the Sierra Club Beyond Coal campaign says the rules don't do enough.

"Most of our coal plants in the state, actually already have technology to reduce smog-causing pollution," Teplitzky said. "They are just not using it."

Power industry appreciates flexibility

The DEP's plan allows power-plant operators to meet the pollution-control standard across several facilities owned by the same company, instead of requiring every individual facility to reduce its pollutant levels to the standard. And that means much-needed flexibility for the power industry, argued the president of the Electric Power Generation Association.

"There are some groups whose stated goal is to put coal-fired generators out of business. To those groups, there would be no standard stringent enough," said Jacob Smeltz whose trade group represents PPL, PECO and other power companies around the state. "What we try to do is strike an appropriate balance."

NOx emissions across Pennsylvania dropped 45 percent between 2000 and 2012, Smeltz said.

In order to critique the DEP's RACT plan, the Sierra Club reviewed the operations history of eight coal plants in Pennsylvania because coal plants are the biggest contributors to smog-causing pollutants in the state, Teplitzky said, and they offer the "quickest, most affordable" opportunity to decrease dangerous ozone.

"Corbett's plan sets limits higher than levels that the plants have proven in the past that they can meet," Teplitzky said.