Industrial smokestacks directly emit particle pollution, but they also emit sulfur dioxide and nitrogen oxides, which react in the atmosphere to form fine particle pollution. Photo courtesy U.S. EPA
Industrial smokestacks directly emit particle pollution, but they also emit sulfur dioxide and nitrogen oxides, which react in the atmosphere to form fine particle pollution. Photo courtesy U.S. EPA

The entire state has complied with federal limits on fine particle pollution, though a landmark state law is not the only reason for pollution reductions.

By Gabe Rivin

North Carolina has met strict federal standards for an air pollutant that endangers human health, according to the state’s environmental regulators.

The N.C. Department of Environment and Natural Resources said the state has met federal limits on fine particles, microscopic airborne pollutants that are generated from power plant pollution and car exhaust. In an Aug. 19 letter to Gov. Pat McCrory, the U.S. Environmental Protection Agency said that the entire state had met the agency’s limits, which in 2012 the EPA lowered from 15 to 12 micrograms per cubic meter.

Particulate matter less than 2.5 micrometers in diameter can cause a variety of health ailments. Graphic courtesy U.S. EPA

The announcement is significant because fine particle pollution poses a considerable hazard to human health. According to the EPA, humans exposed to particle pollution are at a greater risk of heart disease, lung disease and asthma, among other ailments.

Health officials are most concerned about particles that measure less than 2.5 micrometers in diameter, or about one-thirtieth the size of a human hair, according to the EPA. Those particles can penetrate humans’ lungs and enter the bloodstream. Particle pollution can be particularly harmful for children and the elderly.

DENR said particle pollution is among the most widespread air issues in the state, and that from 2005-11 Catawba, Guilford and Davidson counties didn’t meet the EPA’s standards.

Although some of the pollution comes directly from industrial smokestacks and from fires, most of the fine particles form in a complicated atmospheric reaction between chemicals such as sulfur dioxide and nitrogen oxides, which are emitted from power plants and cars, among other sources.

Tom Mather, a public information officer with DENR, said North Carolina’s compliance with the EPA’s rules has much to do with the state’s 2002 Clean Smokestacks law. That law required the state’s coal-fired power plants to make drastic reductions in air pollution.

“To meet those goals, what they did was focus their efforts on the largest plants, and so they added scrubbers and other advanced pollution controls to their largest facilities,” Mather said. “A lot of their older, less efficient plants, they either shut them down or converted to natural gas.”

The drop in pollution has been large.

In 1998, for example, the state’s coal plants emitted 489,000 tons of sulfur dioxide and 245,000 tons of nitrogen oxides. But by 2012, coal plants had reduced their sulfur dioxide emissions to about 53,000 tons and their nitrogen oxide emissions to 41,000 tons.

The health benefits of the law have been considerable, according to one study, which found that North Carolina’s reduction in air pollution was associated with a decrease in respiratory-related deaths.

But Mather, like others, noted that North Carolina’s law wasn’t the only cause for the drop in emissions. The EPA’s air rules for mercury and other toxics, for example, reduced particle pollution, according to John Suttles, a senior attorney and litigation director with the Southern Environmental Law Center.

“Federal standards for vehicles and fuels for vehicles are reducing the amount of particulate emissions coming from cars and trucks,” he said. “All of these things are conspiring to reduce the amount of fine particle pollution in the air.”

The importance of monitoring air

North Carolina may be meeting the EPA’s rules, but it’s hardly the only state to do so.

Industrial smokestacks directly emit particle pollution, but they also emit sulfur dioxide and nitrogen oxides, which react in the atmosphere to form fine particle pollution. Photo courtesy U.S. EPA

In fact, few counties throughout the country will have trouble meeting the EPA’s requirements, according to an agency analysis.

Still, public health stands to benefit when the state complies with EPA’s standards, Suttles said.

“Fine particle pollution is probably, in terms of a class of pollutants, the most harmful pollutant that is emitted from big-industrial sources and also from mobile sources like cars and trucks,” he said

Suttles added that EPA’s revised standard came as health researchers have lowered what they consider to be a safe level of human exposure to particle pollution.

“Over time, we learned that fine particle pollution is more harmful to people at lower doses for shorter periods of exposure than we had previously thought,” he said.

In order to measure that exposure, North Carolina’s statewide network of air-quality monitors offers the state important tools to measure air pollution like fine particles.

But that network would have been diminished under a proposal this year in the General Assembly. The legislation, which didn’t pass in this year’s lengthy short session, would have required the state to remove any air monitors that the EPA doesn’t explicitly require.

DENR’s Mather said that this wouldn’t have hurt the state’s ability to measure particle pollution.

“What we’re measuring in the air is by and large not locally generated, but is regional in scale,” he said.

But the state’s understanding of other air pollution, including in less developed areas, could have been hurt, Mather said.

“A lot of air-quality work is computer modeling, where we’re trying to do projections of what could happen under different scenarios,” he said. “Having fewer monitors would make it difficult to make those kinds of predictions and to do air-quality forecasts.”

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Gabe Rivin

Gabe is our former environmental health reporter from 2014-2016. He is a former editor of The Cooperative Business Journal, and a former reporter for Inside Washington Publishers, where he covered federal...

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