Recent research confirms that the ozone levels in your backyard are comparable to those around interstates and businesses.
The Center for the Environment’s summer air monitoring program, conducted in partnership with Davidson College, showed ozone levels to be fairly consistent in residential areas of seven Piedmont counties. “We know we have high ozone levels in counties where the North Carolina Division of Air Quality has monitors,” says Dr. John Wear, Center director. “But we wanted to know if the levels are also high in the counties that presently have no monitors.”

The study’s intent was to show what the air quality is like in residents’ backyards in Rowan, Cabarrus, Iredell, Davidson, Mecklenburg and Gaston counties in North Carolina and York County in South Carolina. ?
Shelia Armstrong, the Center’s Campaign for Clean Air outreach coordinator, says the results provide confirmation that the ozone levels appear to be consistent throughout the region. “Those counties that don’t have a monitor are able to know for sure that the ozone is the same,” she says.

Ozone levels in the monitored counties averaged around 40 parts per billion (ppb), according to Dr. Cindy Hauser, associate professor of chemistry at Davidson. These levels fluctuated depending on the temperature, she says, but remained on average the same throughout the counties.

Hauser, who analyzed the data with undergraduate research students Alexandra Buckley and Juliana Porter, says the levels were based on seven-day averages, which are different from the averages reported by EPA approved continuous gas phase ozone monitors.
Rowan and Mecklenburg are the only two counties in the program presently monitored by the North Carolina EPA for ozone levels. The 2011 State of the Air Report by the American Lung Association for the years 2007 thru 2009 ranked Rowan as the 17th worst county in the nation (of those monitored) for ozone levels, while Mecklenburg tied with two other counties for the 21st ranking.
The N.C. Division of Air Quality has two monitors in Rowan County. The Mecklenburg County Program has three monitors, one on the Cabarrus County line.
Hauser, who analyzed the data from the program which started May 31 and ended July 27, says she was not surprised by the consistency. “Regional air masses seem to be consistent in terms of secondary air pollutants,” she says. “Perhaps the Gastonia and York county results, which I thought were downwind of Charlotte, were a little surprising, but a lot of traffic flows through those areas.”
Results to be Used to Educate Residents
Results of the study will be used to educate residents on the danger that high ozone levels pose to children, senior citizens and people with respiratory diseases or compromised immune systems. Center staff will also provide information on what citizens can do to reduce the levels. “Vehicle pollution is a primary cause of ozone formation,” Hauser says, adding that residents can help to lower levels by minimizing driving and time spent idling.
Campaign for Clean Air Intern June McDowell trained volunteers in the seven counties on how to put out collectors with tubes and filters to measure ozone and nitrogen oxide (NOx) levels in the air. The Center purchased the equipment for the program with Campaign for Clean Air funds.
Hauser says the volunteers were an essential part of the program. “It would be difficult to have the scale of monitoring without people on the ground in the various counties,” she says. “It is also reassuring to see residents invested in hearing about their air quality.”
Carolyn Glasgow, volunteer for Rowan County, says she was surprised by the consistency of the ozone levels. “I thought Mecklenburg would be higher as far as pollution levels,” she says. The Rowan monitor was placed on a dogwood tree in Glasgow’s back yard in the northeastern section of the county.
Other volunteers for the program were Becca Kirlin of Gaston County, Andrew Plummer of Davidson, Dawn Grant of Cabarrus, Dr. Karen Bernd of Iredell, DeeDee Petronis of Mecklenburg and Steve Pin of York.
Plummer, a 2010 graduate of Catawba College’s environmental science program, says he was pleased not only to see the Center collaborating with Davidson College, but also to see citizens of the seven counties working together on such an important project. “If we could get more folks on board, we could get more data and be able to see how things really are,” he says.
NOx Levels Vary
While ozone levels were constant, Hauser says nitrogen oxide (NOx) levels tended to vary from county to county, demonstrating minimal variations from one week to the next at a specific sampling site.
Hauser says nitrogen oxides are a primary pollutant, a component of vehicle emissions and precursor to ozone formation. “NOx concentrations act as an indicator of pollution levels in an area and are locally specific,” she says. “NOx concentrations were measured in this study to compare the presence of emission sources at each of the sites and to explore their impact on local concentrations of ozone.”
Rowan, Mecklenburg and Davidson counties averaged about 10 parts per billion (ppb) – based on seven-day averages – while the other four counties averaged 13-to-15 parts per billion (ppb).
“I might have expected Mecklenburg to be higher if the monitor was in downtown Charlotte,” Hauser says, “but it wasn’t. It was also at a residential site.”
The York and Gaston sampling sites demonstrated statistically greater NOx concentrations than the other sites, according to Hauser. “This is not unexpected as each of these sites was within a mile of the interstate,” she says. “The sampling sites in Iredell and Cabarrus demonstrated the next highest concentrations and were located in residential areas with a higher density of housing than the samplers in Mecklenburg, Rowan and Davidson counties, which had the lowest concentrations of NOx.
Hauser says she was very pleased with the partnership with the Center for the Environment. “We never could have completed a project of this magnitude without the partnership,” she says.
Pending further analysis of the data from the summer air monitoring program, Armstrong says Campaign staff will release that data to the public to increase understanding about the high ozone levels. “It’s not just along the interstates or at businesses, she says. “It’s everywhere.”