SOS 99 In The News

Environmental News Network article

The following (linked above) is reproduced directly from the Environmental News Network:

Southern air pollution study under way
Friday, June 25, 1999

A P-3 aircraft, similar to these NOAA craft, will gather data during low-altitude flights over the major population and air traffic centers of Atlanta and Nashville.
Scientists are trying to develop tools to fight air pollution by studying hot and humid southern cities such as Atlanta, Ga., and Nashville, Tenn.

In the late 1980s, scientists realized that the South had unique air quality management problems caused by warm temperatures, high humidity, stagnant air and natural emissions of hydrocarbons from the region's large rural and urban forests.

"Large urban heat islands, such as Nashville or Atlanta, surrounded by lush vegetation and forests, cause a unique air pollution mix of human-caused and natural emissions," said James Meagher of the National Oceanic and Atmospheric Administration's Aeronomy Laboratory in Boulder, Colo.

Under the Southern Oxidants Study, government and university researchers will investigate the processes responsible for the formation of ozone pollution and fine particulate matter that is believed to damage crops and forests and affect human health and scenic visibility.

Using planes, helicopters and air monitoring stations located throughout the South, scientists will collect air samples to assess the physical and chemical characteristics of fine particulate matter and ozone.

"The combined activities of this study provide an unparalleled opportunity to describe the production and distribution of ozone and PM throughout the southeast with a level of detail that has hitherto not been possible," said Meagher.

In one such experiment, a P-3 aircraft will gather data during low-altitude flights over the major population and air traffic centers of Atlanta and Nashville. This will give scientists a way to assess the similarities and differences in the air quality of the two cities and allow policy makers to determine the appropriate response to air quality management.

"We're expecting to develop a really good database from these experiments that will provide the sound science needed to find solutions to the special air pollution problems facing this region," said Meagher.

The Bureau of National Affairs article

The following is reproduced from the The Bureau of National Affairs, Inc., Washington D.C.:

Air Pollution, Wednesday, July 7, 1999

Heat Wave Launches Intensive Phase Of Study on Ozone Formation in South

ATLANTA--While residents of Eastern states endured high temperatures over the July 4th weekend, a team of 170 scientists in Nashville were happy to see the weather finally heat up.

The scientists are participating in the Southern Oxidant Study, begun in 1990 and the nation's most comprehensive look at how and why ground-level ozone forms. This summer, researchers are trying to figure out the physical and chemical characteristics of fine particulate matter and ozone, which may be a factor in health-related problems as well as crop and forest damage.

But until the holiday weekend, the unseasonably cool and rainy weather for the last two weeks of June, along with problems with some of the airplanes they are using to take measurements, had restricted researchers to a handful of flights to collect air samples. But that does not mean they are disappointed so far.

"We don't just want to look at high pollution days. We want to be able to understand what happens on days that are clean and, in fact, why they're clean, as much as we want to understand on days that are polluted, why they are polluted," said James Meagher, chief scientist for the project, in a July 2 telephone interview. Meagher is a research chemist at the National Oceanic and Atmospheric Administration's Aeronomy Laboratory in Boulder, Colo.

Rainy days are a problem, however, Meagher said. It is harder to fly on rainy days and the conditions are more difficult to understand and interpret afterwards, he explained.

Airborne scientific teams are conducting the regional research from bases in Atlanta and Nashville.

High Pressure Ridge

But the forecast for the weekend was for hot weather, and the scientists were excited. "We're on the edge now of what looks like a big high pressure ridge that's moving into this area so things are going to get hot and heavy pretty quickly here," Meagher said.

The Southern Oxidant Study is a research effort involving numerous universities and state and federal environmental agencies, with the goal of learning more about air pollution in the South. Here, warm temperatures, high humidity, stagnant air, and natural emissions of hydrocarbons from the region's large rural and urban forests give the region unique air quality management problems.

So far, scientists have learned that instead of the large-scale mixing of the precursors of ozone--nitrogen oxides and volatile organic compounds--it is more like a plate of spaghetti, where plumes twist and turn around each other and mix much more slowly.

According to William Chameides, an atmospheric scientist at the Georgia Institute of Technology, researchers have learned that electric power plant plumes contribute to ozone formation, and "there is a very interesting interaction between power plants and urban plumes in producing ozone."

They have also found that, for reasons that are not entirely understood, the number of ozone molecules produced per molecule of NOx emitted is smaller than scientists originally thought. This means that more NOx reduction is needed, Chameides said in a July 2 telephone interview, to get the region "where we need to be."

Scientists have learned that NOx emitted by large power plants produces less ozone that the NOx emitted by smaller power plants. That might have implications "if you wanted to go to a bunch of small power generators," he said.

"It's very clear that these plumes keep their characteristics for a long, long time and are sort of mixing in a complicated way. We can track power plant plumes way downwind of where they are emitted, which is somewhat of a surprise," Chameides said.

Aircraft at Work

During this summer's part of the study, airplanes and helicopters will take a series of coordinated chemical and meteorological measurements during the day and the night. The samples will be collected over a wide range of the Southeastern and Midwestern United States to assess to what degree the problem is regional or local. Similar experiments are slated for Atlanta later this summer.

The study is in its ninth year, but the 1999 experiments are "bigger" and "more complex" than those conducted four years ago, Meagher said, and represent the most extensive sampling to date for the study. The team had more aircraft in 1995, but much more extensive ground monitoring in 1999.

The sampling instruments, both on the chemical measurement side and the particle measurement side, are greatly improved, Meagher said. They include "a really nice array of meteorological instrumentation" that allows them to look at the dynamics of the meteorology in greater detail, he said.

For example, they have learned that outflows from some of the gust fronts that are created when small thunderstorms go by produce low-level cold winds from high in the atmosphere virtually down into the city of Nashville. "It's really interesting to see some of those kinds of things," Meagher said.

The last flight for the Nashville portion is scheduled for July 17.

The scientists participating in the Southern Oxidant Study will publish papers on the results in scientific literature over the next two or three years, Meagher said. Concurrently, the team will put out "more user-friendly information" for the policymaking community, he added.

By Barney Tumey

Christian Science Monitor article

The following (linked above) is reproduced directly from the Christian Science Monitor:

THURSDAY, AUGUST 5, 1999

Clearing our view of smog

Scientists help Sun Belt cities find regional solutions to air-pollution problems

Peter N. Spotts
Staff writer of The Christian Science Monitor

NASHVILLE, TENN.

Fred Fehsenfeld looks out a window aboard Miss Piggy, a federal hurricane-research plane, and nods at the gray-brown haze staining the popcorn clouds rising in the midday heat.

"You know, people move to Nashville thinking the air will be clean," the courtly atmospheric chemist drawls. "But it's anything but clean."

Flying for hours at altitudes low enough to count cows at the watering hole, Miss Piggy will log 1,500 miles on this run. The researchers hunched over consoles down her cabin are part of a small army of scientists who converged on Nashville, Tenn., this summer to solve the puzzle of smog in the Southern United States and how best to battle it.

It has become increasingly clear, researchers say, that air-pollution control strategies based on conditions in Los Angeles or the Boston-to-Washington corridor may not help burgeoning Sun Belt cities such as Atlanta or Nashville meet tighter federal air-quality standards.

ILLUSTRATION BY ARI DENISON

The Environmental Protection Agency adopted more-stringent ozone rules and tighter regulations for dust particles, which can come from natural and man-made sources. Both standards, adopted two years ago, are tied up in federal court.

"Air-quality management in this country is a remarkable success," notes Dr. Fehsenfeld, of the National Oceanic and Atmospheric Administration's Aeronomy Laboratory in Boulder, Colo., who is an associate director at the University of Colorado's Cooperative Institute for Research in Environmental Sciences. "Cities would almost be unbearable without it. But air quality management is not one size fits all."

"We've been struggling in the US since 1990 to manage ozone and air quality," adds Ellis Cowling, a forest biologist at North Carolina State University in Raleigh, and director of the Southern Oxidants Study (SOS), the program conducting the Nashville experiment. "We've made some progress. The peaks in ozone concentrations are down. But average ozone concentrations have been growing at the same time." This is despite billions of dollars spent on air-pollution control efforts during the past decade.

Since 1988, the SOS project - a cooperative program involving some university scientists, state and federal agencies, and private companies - has been conducting field experiments to get a better handle on the factors contributing to the South's smog problem. The Nashville field campaign represents the most ambitious effort the project has yet undertaken.

The first Nashville campaigns were conducted during the summers of 1994 and 1995. Results from those studies yielded such surprises that the project targeted the city for a six-week effort this year.

Two broad factors separate the Southern US from much of the rest of the country in the battle against urban smog, Dr. Cowling says: weather and trees.

Summer-like weather lingers far longer in the South, where scorching daytime temperatures and stagnant air turn the first several thousand feet of atmosphere here into a solar-powered chemical factory. In urban areas, sunlight provides the energy for reactions that combine oxygen molecules with carbon monoxide, or with hydrocarbons from sources such as auto exhaust, to form ozone.

But since the late 1980s, researchers have grown increasingly attuned to the role tree-made hydrocarbons play in forming ozone over rural areas. Either the hydrocarbons or the ozone itself can carry to cities, compounding urban ozone woes.

Trees as culprit

The key forest-based hydrocarbon in the South is isoprene, which is produced in copious amounts by oaks and members of the poplar family, according to Russell Monson, a professor of environmental biology at the University of Colorado. Research in the region has shown that even forests dominated by pine, which emits its own brand of hydrocarbon, produce vast amounts of isoprene. It comes from plants that make up the pine forest's ground cover.

"Why plants produce isoprene remains a bit of a mystery," Dr. Monson says. One notion holds that the compound stabilizes membranes in plants struggling to sustain photosynthesis during hot weather. This explanation, he adds, is controversial; recent experiments have cast doubt on it.

IT'S MIDDAY. CAN YOU SEE CITY HALL? Los Angeles has cleaned up its act considerably since this photo was taken in 1953.
AP PHOTOS/LOS ANGELES TIMES

Isoprene's contribution to ozone production in the presence of a stew of other man-made gases became apparent after strict controls on auto hydrocarbon emissions did little to reduce urban ozone in the South.

"The problem is that forests around many Southern cities have so many oaks, and isoprene is many times more reactive with the atmosphere than man-made hydrocarbons," Monson explains. "This meant that although monitoring programs showed a significant decline in hydrocarbon emissions from autos, ozone didn't go away."

Faced with that conundrum, researchers took to the field. And nowhere, researchers say, do air-pollution conditions unique to the South appear as tidily as they do here at the home of the Grand Ole Opry - a growing urban island surrounded by a sea of woods, whose region includes several coal-fired power plants owned by the Tennessee Valley Authority, one of the participants in the Nashville studies.

Headquartered on the second floor of a nondescript two-story building at Nashville International Airport, the research effort includes ground stations in downtown Nashville and throughout central Tennessee. One site, on a farm within the city limits, has the look of a high-tech Woodstock camp.

As Miss Piggy bumps and sways her way through the unstable air along today's research track, Fehsenfeld reflects on key 1994-1995 results that brought him and his colleagues back to Nashville. The first involves nitrogen oxides, byproducts of combustion without which ozone would not form, he says. Large "point sources" for nitrogen oxides, such as big power plants, turn out to be less efficient at producing ozone than smaller sources, because the rate of ozone production is sensitive to concentrations of nitrogen oxides. He likens it to burning fuel in a car's engine; the fuel burns most efficiently when air and fuel mix in the right proportions.

From a policy standpoint, he continues, the results imply that targeting big power plants for nitrogen-oxide reductions may provide "less bang for the buck" than going after smaller point sources or dispersed sources such as automobiles. Likewise, dealing with emissions of nitrogen oxides by building lots of small power plants instead of one big one could aggravate ozone problems, he notes.

In another key result, he says, scientists were surprised to find that on a regional basis, "isoprene dominates photochemical reactions" forming ozone. Isoprene continues to baffle the research team this year.

"For the first time, we've seen very high concentrations of isoprene at night, and we don't understand it," says Nashville study director James Meagher, also from NOAA's Aeronomy Laboratory. "We know that plants do not produce isoprene at night."

Perhaps it blows in from somewhere else, such as the Great Smoky Mountains, he speculates. Regardless of its source, nighttime concentrations provide a ready reservoir of hydrocarbons to begin the next day's ozone production.

This year marks the first time the project has included particulate studies. The effort is a response to the new EPA regulations, which cite health and aesthetic reasons for wanting to reduce dust haze, as well as to uncertainties about the role particulates play in atmospheric chemistry.

Although researchers often see tiny particles as necessary "platforms" on which chemical reactions take place in the atmosphere, "particulates are a big unknown," says University of Denver atmospheric chemist Charles Brock. "They are something to throw in as answers to holes in our understanding of chemical reactions. But it's equally likely that the holes result from measurement errors."

Dust from Africa

Regardless of the role particulates play, controlling them could be challenging. A 23-year study of dust over Miami indicates that during some summers, up to 50 percent of the fine particles present comes from Africa, not from local sources, according to Joseph Prospero, an atmospheric chemist at the University of Miami. The dust is transported by the same circulation patterns that steer hurricanes across the Atlantic.

His study, published in the July 20 issue of the Journal of Geophysical Research, plus evidence from satellites and more-limited studies elsewhere in the Southeast, led him to conclude that the problem is not limited to Miami, but could well embrace much of the Southeast.

Moreover, those concentrations can reach levels that "could put a city over the top" for dust regulations, even though dust from local sources alone wouldn't constitute a violation.

"Air-quality people need to be aware that African dust is a pretty substantial component" of the Southeast's summertime dust problem, Dr. Prospero says.

Indeed, researchers say, the message that SOS studies, as well as others, continue to drive home is that pollution, or the precursor chemicals that lead to it, know no boundaries.

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