Last year’s reduction in bad ozone days is the result of actual improvements but is also weather-related. That summer was the third wettest in the past 119 years, and meaning less sunlight and less opportunity for the toxic compound to form.

Only one monitor statewide in the Winston-Salem area spiked above the Environmental Protection Agency’s standard for ozone, and only once. The year before, there were spikes on 16 days around the state.

“If we get back to a more typical summer this year, we will likely see the number of exceedances go up, but over time we’ve seen that nice downward trend,” said Sheila Holman, director of the N.C. Department of Environment and Natural Resources Division of Air Quality.

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But 2013’s low values weren’t all a trick of the weather. Air quality in North Carolina has been steadily improving over the past couple of decades. The state has completely met standards for fine particles, lead, nitrogen oxide and sulfur dioxide.

As far as ozone, everywhere save the Charlotte area is currently in compliance with federal ozone standards.

The federal standard, 75 parts per billion, is based on an average of high ozone days over three years.

Some parts of the state are well below that level of 75 ppb, with monitors in WNC recording the lowest levels.

Swain County was the winner, recording 58 ppb of ozone in 2013. Haywood comes in at 69 ppb.

Both Haywood and Swain have come down 4 to 6 parts per billion since the 2007-2009 average — a reduction of 7 to 10 percent in just five years.

“This is the first time in my 21 years with the division that I’ve seen values that low, so we are improving,” Holman said, one of several speakers at the Ozone Season Kickoff press conference last week hosted by Land of the Sky Regional Council, which brings air quality experts together each spring to discuss trends, regulations and innovations.

What’s going right?

A lot of the credit for the improving ozone situation goes to the Clean Smokestack Act, a state law passed in 2002. The act placed a cap on certain emissions, requiring factories and power plants to meet new, tougher standards by 2009. 

By 2010, Duke Energy and Progress Energy coal-fired power plants had reduced their emissions of nitrogen oxide — a key ingredient in ozone — from 245,000 tons to 47,180 tons, comfortably below the 2009 cap of 56,000 tons. Likewise, the companies’ sulfur dioxide emissions plummeted from 489,000 tons in 1998 to 116,500 in 2010, meeting both the 2009 and 2013 caps of 250,000 and 130,000 tons, respectively.

“All of our coal-fired power plants obviously have put on state-of-the-art controls. The question becomes where do we go for additional reductions?” Holman said. “That’s where I want to underscore the importance of the volunteer programs, the outreach programs that our partners have been working on for years. That, I think, is going to be the key to our success.” 

Changes on the horizon

Because the reductions will have to keep coming. The first ozone standard came on in 1997, and North Carolina met that. The second came in 2008, and all but two of the state’s 31 monitors have met them.

Now, the EPA is looking to revise the ozone standard yet again. 

“Probably in late 2015 we’ll see a new revised ozone standard,” Holman said. 

Right now, the standard sits at 75 parts per billion, compared to the 35 ppb that the EPA considers “natural background,” the ozone that would be in the atmosphere regardless of humans. The new allowable ozone level will likely sit between 60 and 70 ppb, Holman said. 

As far as North Carolina is concerned, there’s a big difference between those two numbers. At 70 ppb, not much would have to change. Only the major metropolitan areas of the state exceed that level now.

But if the EPA lowers the threshold to 65 ppb, the three counties in the eight-county mountain region that have ozone monitors would be out of compliance, along with much of the eastern part of the state.

And at 60 ppb, only one of the state’s 30 counties with ozone monitors would be in compliance — Swain County, which now records 58 ppb. 

Haywood’s average of 69 ppb is higher than Swain’s, due in part to its high-elevation monitors, where ozone tends to collect. Swain’s monitor is at a lower elevation.

If the state didn’t meet the new EPA limit, it would go on a monitored improvement plan.

“If you’re nonattainment, it triggers requirements that you have to meet in order to continue to reduce your concentration,” explained Paul Muller, regional supervisor for the Department of Air Quality. 

Individual states must have plans in place for how to handle areas that don’t meet the ozone standards, and the EPA has to approve their approach. That’s where environment often intersects with industry. 

“Typically what we’ve seen in areas like Charlotte that’s been non-attaining for a while is we see smaller projects going in that are below the thresholds, but we don’t see many bigger projects going in,” Holman said. “So it does have economic repercussions.” 

Challenges to reducing 

Ozone levels aren’t solely a product of industry, though, and they’re not solely local. In the coming years, environmental agencies will have to work together to manage air pollution that travels across state lines. 

That’s a necessity especially pertinent to the highest-elevation areas of the Smokies, where ozone follows a different pattern than in valleys and urban areas. The Division of Air Quality is still trying to determine the best way to deal with mountain ozone, because spikes in ozone there point to air transport rather than to local pollution sources. 

“Part of our challenge is trying to understand what air is impacting those mountain sites,” Holman said.  

The Smokies get wafting ozone from sources such as coal-fired power plants in Tennessee and traffic in Atlanta. After cleaning up its own emissions through the Clean Smokestacks Act, the state of North Carolina sued in federal court to force coal-fired plants in neighboring states to install modern pollution controls, successfully proving that the mountains of WNC were suffering from air pollution due to laxer controls on some coal plants to the west.

Statewide, local leadership will have to address ozone ingredients produced through vehicle emissions. The greater Asheville area is going through a growth spurt, and more people means more of everything else, too. 

“We’re going to have a lot of growth, and that’s a good thing,” Eaker said. “It will help our economies. But we’re going to have a lot more people, a lot more vehicles, a lot more homes to heat, so we have to work with these people to reduce our emissions sources.” 

That’s where Holman’s call for help from volunteer groups and organizations will come into play. Even simple lifestyle choices like reducing vehicle use by carpooling, telecommuting, combining errands, walking or biking to work and reducing idling can help reduce nitrogen oxide emissions. Keeping engines tuned up and buying fuel-efficient vehicles are other ways to contribute. 

Movement in the auto industry 

And when it comes to fuel-efficient vehicles, the auto industry is giving consumers some help. With each passing year, vehicles become cleaner, burning less fuel and emitting less pollution.

That’s partly due to consumer demand driven by a desire for cheaper per-mile transportation and for alternatives to gasoline-powered cars. 

It’s also partly a result of heightening standards for the auto industry. Between 2017 and 2025, new regulations will be phased in for new cars and trucks.

The requirements are expected to reduce emissions of volatile organic compounds and nitrogen oxide — the two ingredients for ozone — by 80 percent compared to today’s average.

“As the fleets turn over, we’ll continue to see emissions decline,” Holman said.

But will they decline enough to keep up with the standard? That will depend on what threshold the EPA decides on, on what kind of emission reduction technology becomes available — and how cheaply — and on how much individuals buy in to create a cumulative reduction.

The variables are many, but North Carolina’s outlook for air quality in general and ozone in particular seems positive, Holman said. And that’s a trend she’s optimistic will continue. 

“There’s lots happening,” Holman said, “And that I think will help keep North Carolina’s trend going downwards.” 

What is ozone? 

There’s the good ozone we all know about: the ozone layer high in the atmosphere that protects Earth from harmful ultraviolent rays.

But ground ozone, is a different story. High ozone levels can cause symptoms such as coughing, throat irritation and chest pain. It can worsen bronchitis, asthma and emphysema, and lung scarring can occur from repeated exposure.

Plants also suffer. High ozone can cause tan flecks, red spots and stipples between the veins of the leaves, and it can keep plants from producing as much seed or fruit as they otherwise would. 

Without any help from humans, ozone would naturally make up about 35 parts per billion of the air, but emissions from vehicles and industry cause ozone levels to shoot far above that.

The compound — three oxygen atoms bound together — forms when nitrogen oxide and volatile organic compounds react in the presence of sunlight, making ozone mostly a summertime issue. In recent decades, state and federal organizations have been trying to reduce emissions of ozone ingredients.