CHICAGO -- One transportation-related industry remains a holdout in the decades-long push to eliminate leaded gasoline as a motor fuel in the United States.
While U.S. sales of leaded gasoline for automobiles was halted in the 1990s, piston-engine aircraft, which take off from airports large and small in every state, still run on leaded aviation fuel known as avgas.
As pollution from other sources has sharply declined, the general aviation fleet of 167,000 aircraft has become the nation's top source of airborne lead, emitting nearly 500 tons a year, according to the U.S. Environmental Protection Agency.
Lead particles from airplane exhaust tend to be concentrated close to airports, but they also fall widely during flight. About 16 million people live and 3 million children go to school within a half-mile of an airport where leaded avgas is sold, the EPA estimates.
"For years the federal government has been telling us there is no safe level of lead," said Marcie Keever, a lawyer for Friends of the Earth, a Washington, D.C.-based environmental group that petitioned the EPA last month to ban leaded aviation fuel. "We are well past the time for them to do something about this."
Four years ago, the EPA announced plans to phase out leaded aviation fuel with regulations similar to the ban on leaded gasoline. But the agency held back on filing rules after the aviation industry and members of Congress objected.
Representatives from aviation and oil companies say adding lead is a necessary safety measure because it boosts the octane of fuel high enough to prevent engine failure during flight. They say the government shouldn't ban avgas until a lead-free alternative is widely available.
Industry executives acknowledge that at least 75 percent of the piston-engine aircraft in the United States already can operate safely on high-octane gasoline made without ethanol, which is readily available and has the added benefit of being less expensive than avgas.
But the market is so small that most airports sell only two types of fuel: leaded avgas for piston-engine aircraft and jet fuel for everything else.
Airport executives and fuel suppliers say there isn't enough demand to merit installing extra fuel tanks for unleaded gas.
"Our avgas sales have been on the decline for about 20 years," said David Bird, executive director of DuPage County Airport in Illinois, which saw more than 40,000 general aviation takeoffs last year. "If there's a change in EPA rules, we will certainly comply."
The chief barrier to lead-free alternatives is the relatively small fleet of planes that can fly only on avgas. Industry groups estimate that up to 70 percent of the leaded fuel sold in the United States is used by 25 percent of the piston-engine aircraft, many of which are operated by charter airlines or companies that fly people and supplies to remote parts of Alaska.
"Premature regulation, before viable fuel alternatives are available, is simply untenable and irresponsible," the Alaska Air Carriers Association wrote in a 2011 letter urging EPA officials to give the aviation industry up to 30 years to phase out leaded fuel.
In another letter to the EPA, a bipartisan group of 27 U.S. senators led by Republican John Thune of South Dakota and Democrat Mark Begich of Alaska said banning avgas would result in an "incredible cost to aircraft owners, operators and the consumers who rely on their service."
An EPA spokesman declined to make someone available to answer questions. In an emailed statement, the agency said it intends to make a final decision about avgas regulations by mid-2015.
Fuel suppliers already have reduced the amount of lead added to aviation fuel, which combined with a decline in the number of piston-engine aircraft has steadily cut emissions during the past three decades. Aviation emitted 484 tons of lead in 2011, the last year for which figures are available, down from 74,000 tons in 1980.
The question is whether any continued use of lead is acceptable given its well-documented health hazards. Leaded automobile gasoline is still sold in only six countries: Afghanistan, Algeria, Iraq, Myanmar, North Korea and Yemen. Since the use of lead in gasoline was barred, the amount of lead churned into the air by cars and factories in the United States has declined by more than 90 percent compared with the 1970s.
Each of the 522,000 gallons of avgas sold daily in the United States last year contained 2 grams of tetraethyl lead, the same highly toxic substance added to automobile gasoline during most of the last century.
Unlike many other pollutants, lead doesn't break down over time and can linger for years in the top few inches of soil. Children are most commonly exposed when they ingest lead paint dust in older houses or dirt contaminated with the toxic metal.
Studies show that even tiny amounts in young children can trigger learning disabilities and aggression.
The EPA has been monitoring lead emissions at 17 airports, none of which are in the Chicago area. Two airports -- San Carlos and McClellan-Palomar in California -- have violated the federal lead limit of 1.5 micrograms per cubic centimeter of air, according to preliminary test results reported last year.
In 2000, the Illinois Environmental Protection Agency found that airborne lead pollution was significantly higher downwind from O'Hare than upwind.
More recently, Duke University researchers reported in 2011 that children had higher levels of lead in their blood if they lived downwind from airports in North Carolina. Lead levels were highest in kids who lived within a third of a mile of an airport, the peer-reviewed study found.
Aviation poses unique challenges, industry representatives say.
"Unlike the transition away from leaded gas in automobiles, performance issues in aircraft have life-and-death consequences for pilots and passengers," says the General Aviation Avgas Coalition, a trade group representing aircraft manufacturers, pilots, charter businesses and fuel suppliers.
For its part, the Federal Aviation Administration has created a task force of government and industry officials to study alternative fuels. After a decade of legal and political pressure from green groups, Congress earmarked $5 million a year for the program, which according to the FAA website is expected to certify lead-free aviation fuel in 2018.
In a statement, the FAA said it "may not be technically feasible" to develop an unleaded fuel that could be used without overhauling aircraft engines. Three companies have announced they intend to submit lead-free fuel for FAA review.
SundayMonday Business on 05/25/2014