High Country maintains excellent air quality

Dylan LightfootStaff

January 30, 2013

Ashe County has its share of woes and worries, but at least we can breathe the air.

Tom Mathers, spokesperson for the N.C. Department of Environment and Natural Resources (DENR), said “air quality in the mountains is the best in the state,” based on standards for airborne particulate matter and ozone levels.

“Generally, the mountains and the coast maintain better air quality (due to) more wind and rain, and fewer people, less traffic and less industry,” he said.

Standards for various air pollutants set by the Environmental Protection Agency (EPA) are used by the DENS to determine whether pollution levels pose health risks for populations, Mathers said. Air quality is tested at monitoring stations across the state.

Because air quality is a regional condition, and because stations require staff and expensive equipment, the DENR operates only about 40 of them throughout the 100 counties, he said. Ashe County has no monitoring stations.

The nearest station measuring particulate matter (PM) is in Watauga County. Defined by the EPA as “a mixture of solid particles and liquid droplets found in the air,” PM has a safe level standard of 15 mg per cubic meter.

Watauga has the lowest PM in the state, with an average 8.5 mg per cubic meter. The highest in the state on Tuesday was the Greenville area, which had 60 mg, with air quality listed as “unhealthy for sensitive groups” by the DENS.

“Particulate matter is very fine particles which, when you breathe them in, get very deep in your lungs and can enter your bloodstream,” Mathers said. High PM pollution causes air to appear hazy, although, at 2.5 microns across — about one-fourth the diameter of a pollen grain — the particles themselves are too small to be seen.

The DENR standard for ozone pollution is 75 parts per billion (ppb), based on an EPA formula for a three-year average.

Area ground-level ozone is measured in Avery County, Mathers said, which most recently registered 62 ppb. In contrast, Charlotte is ranked as one of the 25 most ozone-polluted metropolitan areas in the U.S. by the American Lung Association.

Ozone is formed by photochemical reactions between two other air pollutants: volatile organic compounds (from paint, pesticides, etc.) and nitrogen oxides. These reactions typically depend upon the presence of heat and sunlight, resulting in higher ozone concentrations in summer months, according to the EPA.

Stations monitoring other pollutants like sulfur dioxide and carbon monoxide are located in areas with higher populations, more traffic and industry, Mathers said. Levels of these pollutants tend to be very low in the mountains, he said.

The link between elevated air pollution and compromised health is well documented. Negative effects of ambient air pollution especially PM and ozone include decreased lung function, chronic bronchitis, asthma, and other adverse pulmonary effects, according to the County Health Rankings and Roadmaps (CHRR) project.

In 2012, Ashe County had zero PM days, defined by CHHR as the “annual number of unhealthy air quality days due to fine particulate matter.” Statewide, the county average was one PM day for 2012, putting N.C. in the 90th percentile nationwide.

Ashe also had zero unhealthy air quality days from ozone in 2012.

As there are effectively no air quality alerts for the High Country.

Mathers said Asheville’s status should be taken as the best, closest indicator for air quality forecasts, especially when wildfires are present in the region.

One air quality concern specific to the High Country comes from wood smoke gathering under inversions — pools of cold air collecting low lying areas. “You can get high concentrations of particulate matter in the a.m.,” he said.