USA:Air pollution from other countries drifts intoUSA
By Traci Watson, USA TODAY
WASHINGTON, 14 March 2004 Americans drive imported cars, wear imported clothes and chug imported beers.Now scientists are discovering another, less welcome import into the USA: airpollution.
Mercury from China, dust from Africa, smog from Mexico all of it drifts freely across U.S. borders and contaminates the air millions ofAmericans breathe, according to recent research from Harvard University, theUniversity of Washington and many other institutions where scientists arestudying air pollution. There are no boundaries in the sky to stop suchpollution, no Border Patrol agents to capture it.
Pollution wafting into the USA accounts for 30% of thenation’s ozone, an important component of smog, says researcher David Parrish ofthe National Oceanic and Atmospheric Administration. By the year 2020, HarvardUniversity’s Daniel Jacob says, imported pollution will be the primary factordegrading visibility in our national parks.
While the United States is cutting its own emissions, somenations, especially China, are belching out more and more dirty air. As a result,overseas pollution could partly cancel out improvements in U.S. air quality thathave cost billions of dollars.
Among the efforts that could be undermined: theEnvironmental Protection Agency’s new drive to cut power plants’ emissions ofozone-forming chemicals and particle pollution, specks of chemicals that damagehealth. The EPA finalized the rule Thursday.
The EPA will announce limits Tuesday on mercury emitted byU.S. power plants. But the agency estimates that 40% of the mercury that sinksout of the air and lands in the USA comes from overseas.
“A number of things are getting here that we’reworried about,” says David Streets, an environmental scientist at ArgonneNational Laboratory in Chicago. “Some of these (pollutants) are not easy tocontrol. … I don’t expect things to get better in the next 10 years or so, andsome things will get worse.”
Almost every place in the USA has suffered from theeffects of imported air pollution, at least occasionally. Some of the mostserious impacts:
Mercury emitted by power plants and factories inChina, Korea and other parts of Asia wafts over to the USA and settles into thenation’s lakes and streams, where it contributes to pollution that makes fishunsafe to eat.
Dust from Africa’s Sahara Desert blows west across theAtlantic Ocean and helps raise particle levels above federal health standards inMiami and other Southern cities.
Haze and ozone from factories, power plants and firesin Asia and Mexico infiltrate wilderness spots such as California’s SequoiaNational Park and Texas’ Big Bend National Park, clouding views and making theair less healthy.
Scientists who study air quality have long known that airpollution seeps into the USA from abroad. But only recently have they realizedthat the problem has an enormous reach an idea that at first met withresistance.
“A lot of scientists were skeptical,” saysDaniel Jaffe of the University of Washington at Bothell, recalling the reactionto his early findings. “There was a lot of, ‘Oh, come on now.’ “
But aerial and ground-based sensors that detected thechemical fingerprints of pollutants floating across oceans helped erase doubts.So did new satellites that in the last 10 years gave scientists a bird’s-eyeview of clouds of pollution drifting from continent to continent.
From Africa to Alabama
When dust from the Gobi Desert in China and Mongoliaheaded for North America in 1998, “you could actually see it like yellowink snaking across the Pacific,” says Rudolf Husar, who studies atmosphericchemistry at Washington University in St. Louis.
The dust cloud was so thick that when it reached the USA,officials in Washington and Oregon issued warnings about unhealthful air quality,Husar says. Other Asian dust storms have polluted the skies in Savannah, Ga.,and Maine.
African dust doesn’t migrate as far into the USA as itsAsian cousin. But it can get to places such as northern Alabama and southernTennessee, which suffer from significant homegrown emissions. The combination oflocal and imported pollution causes particle levels to soar above federal healthlimits, Husar says.
Human health suffers when dust plumes drift into town.Clouds of dust or smoke contain microscopic particles that, when inhaled,penetrate deep into the lungs. Studies in publications such as The NewEngland Journal of Medicine have found that cities with chronically highlevels of particles have higher death rates, mostly from heart and lung disease.And emergency-room visits and death rates rise in the days following a spike inparticle pollution.
In 1998, a plume of smoke drifted north from fires thathad been set by farmers in Central America to clear fields. It blanketed citiesfrom Austin, Texas, to Altoona, Pa., and “undoubtedly increased mortality”there, says John Bachmann, a science and policy director for the EPA. The plumewas so thick that it caused partial closure of the main airport in St. Louis.
Ozone that comes ashore in the USA isn’t as easy to spotas dust, because satellites can’t see it. It’s a colorless gas that burns thelungs and exacerbates heart disease. It forms in the presence of sunlight whenemissions from the burning of fossil fuels mix with vapors from substances suchas paint, solvents and even fingernail polish. Ozone is the main ingredient insmog.
Though ozone is hard to trace, scientists have learnedenough to realize that every gust of air that blows into the USA has more ozonein it now than it did 20 years ago.
Some of the ozone in that air originated in the USA andreturns here after circling the globe. But U.S. emissions did not cause therecent rise in global ozone U.S. air pollution restrictions have decreasedthe emissions that produce ozone. Debate continues on what did cause theworldwide increase. It could be higher emissions from Asian industries. Or itcould be from commercial ships, which lack pollution controls.
Whatever the cause, the higher ozone level affects airquality, especially in cities often hit by air currents from overseas.
The EPA’s Bachmann says the base-line ozone content of theworld’s air has at least doubled since the Industrial Revolution. That meansbase-line ozone alone gets U.S. air uncomfortably close to being unhealthy.”That’s pretty spooky,” he says.
‘You don’t see anything’
The outlook for the future is even spookier. Asianpollution, scientists say, has the potential to help negate the United States’work to clean up its air.
Asked if he’s concerned about the rising emissions fromAsia’s growing industry, the EPA’s Bachmann answers, “You bet.”
He cites Los Angles as an example of a potential problemspot. The city has some of the worst ozone in the nation, and it’s not clear howto make the air healthy.
Los Angeles may get as much as 50 parts per billion of itsozone from overseas, on top of the ozone created by local vehicles. A “CodeOrange” alert warning indicating the air is unhealthy for sensitivepeople is issued when ozone levels average 80 parts per billion
Growth in imported pollution could also undermine a newrule to limit power-plant emissions. Issued Thursday, it’s intended to forcepower plants in the eastern USA to eliminate 61% of the emissions ofozone-forming chemicals by 2015.
Streets estimates that Asian emissions of those chemicalsdoubled from 1985 to 2000 and are still rising. That will reduce the benefit ofthe new power plant rule.
Jacob also worries about foreign pollution’s effect onviews in U.S. national parks. U.S. law requires the restoration of naturalvisibility in places such as Arizona’s Glen Canyon National Recreation Area. Buthaze caused by Asian dust storms sometimes obscures the landscape in the parks.The haze could make it difficult, if not impossible, to reach visibility goalsand also is bad for people’s health.
Even today, “if you go to the Western national parksduring the springtime, you’re very likely to have your visibility decreased byAsian dust,” Jacob says. “In a big (dust) storm, you don’t seeanything.”
Despite the influx of dirty air from abroad, the bulk ofUSA’s air pollution comes from U.S. tailpipes and smokestacks. So scientistssuch as Jaffe say cleaning up domestic emissions is still the most importantstep the United States can take to clean up its air.
Europeans probably would approve of that advice, becauseair pollution from the USA crosses the Atlantic to choke the Old World.
In 2001, for example, a cloud of fumes from the easternUSA traveled far enough to cause high levels of ozone in the Alps, according toa study in the January issue of the Journal of Geophysical Research.
Aware that it gives as well as gets air pollution, theUnited States has taken steps to address the two-way flow. In 2000, Canada andthe United States signed a treaty requiring both nations to reduce ozone-forminggases. Air-quality managers from El Paso, and Juarez, Mexico, work on how tocontrol ozone and particle pollution that crosses the border both ways.
But at talks in the past year, the U.S. government opposeda stringent treaty to control mercury, which is emitted by coal-burning powerplants and factories. Several European countries support mandatory mercurylimits. The United States argued instead for technical aid to teach countrieshow to control their mercury emissions.
As for the national parks, Bachmann says the United Stateswants “to work with the international community” to clean up pollution.But no global binding treaties are in the works.
That will have to change, some scientists say. The recentresearch “really points to the need for global cooperation,” Jaffesays. “It’s only one planet, and we’ve got to learn to live on it.”