Up in
the Air: New Worries About ‘Fume Events’ on Planes By SARAH
NASSAUER
The Wall Street Journal
Any frequent flier knows that air on a plane can get
pretty foul. But can it be toxic?
Flight crews and travelers are increasingly concerned
with that question, amid growing attention to a
particular aspect of the air pumped into planes. Air
travelers breathe a combination of recycled cabin air
and outside fresh air that has been compressed by the
aircraft’s engines - known as "bleed air." But when the
system malfunctions, chemical contaminants can
occasionally end up circulating through the airplane,
creating a so-called fume event.
Airline companies and jet manufacturers say that fume
events are rare, and that when they do occur, air
quality still exceeds safety standards. But unions
representing pilots and flight attendants say the
chemicals entering the aircraft cabin can endanger the
health of flight crews and passengers.
Some unions have begun warning their members of
potential respiratory and neurological dangers. At least
two lawsuits have been filed in the U.S. by passengers
and airline workers claiming contaminated cabin air made
them sick. And investigations by the Federal Aviation
Administration and other regulators around the world are
seeking to determine what chemicals might be introduced,
and what the health effects might be, when compressed
engine air becomes contaminated with residues of engine
oil, hydraulic fluid or other substances.
Some small studies already completed have generally been
inconclusive, largely because of the difficulty of
monitoring contamination events that occur so
infrequently.
One such incident is suspected of having taken place on
US Airways flight 1231 from Philadelphia to Tampa in
March. When an unidentifiable smell floated through the
cabin during the flight, one flight attendant thought it
smelled like vomit, while the plane’s first officer
believed "it didn’t smell toxic, just very unpleasant,"
according to Judith Murawski, a health-hazards
researcher at the Association of Flight Attendants who
spoke to some of the crew after the incident.
By the time the Airbus 319 plane landed in Tampa around
9 p.m., some of the crew and passengers complained of
feeling sick with headaches, itchy eyes, sore throats
and nausea, Ms. Murawski said. Many of the crew spent
the night at a local hospital having blood drawn and
getting chest X-rays, she said.
According to US Airways maintenance records, which were
reviewed by The Wall Street Journal, the airline’s
maintenance crew determined that the strange smell
occurred because of an oil leak in the plane’s auxiliary
power unit, a small engine that powers an airplane’s
ventilation and other systems while the craft is still
on the ground.
Oil leaks in the auxiliary power unit have "been known
to cause an unpleasant smell in the aircraft," said
Morgan Durrant, a US Airways Group Inc. spokesman. But
the airline doesn’t believe it’s a hazard to anyone’s
health, he says. Still, after some crew of the
Tampa-bound flight sought medical attention, the airline
investigated the cause in line with company policy. "In
this case, we changed the auxiliary power unit the next
day," he said. He said the airline had no record that
passengers sought medical assistance after the flight.
A spokeswoman for Airbus, a unit of European Aeronautic
Defense & Space Co., said: "Airbus aircraft are designed
to avoid air contamination in normal operating
conditions."
Aircraft rely on engine bleed air to pressurize cabins,
provide ventilation and other uses. Once compressed, the
air is cooled and sent into the cabin and cockpit. About
50% of the air in a plane’s cabin is bleed air, and the
rest is filtered recirculated air. Cockpits sometimes
use 100% bleed air.
Leaking Engine Seals
Bleed air can get contaminated from engine oils and
fluids when seals leak or when maintenance crews
overfill fluid reservoirs. One contaminant that has
raised concerns among airline unions and some scientists
is tricresyl phosphate, an antiwear additive found in
the engine oil of commercial jet liners that has been
linked to neurological damage when ingested.
Terry Williams, a 40-year-old flight attendant with
American Airlines, recently sued Boeing Co. and its
McDonnell Douglas subsidiary after she started to feel
sick during an April 2007 flight. After the plane
touched down in Dallas, she observed "a smoky mist
spewing from the ventilation system," according to the
complaint. Since then, Ms. Williams said, she has
experienced tremors, vision problems and headaches.
"It’s been a complete life change. I’m a mother of a 3-
and a 5-year-old," said Ms. Williams, who is currently
on disability leave.
AMR Corp.’s American Airlines, which wasn’t named in the
lawsuit, declined to comment on the incident.
Boeing also faces a lawsuit filed by a group of 20
passengers who flew on a charter flight from London to
Orlando, Fla., in February 2007. The group says bleed
air contaminated by an oil leak made them sick on a
Boeing 767, according to the complaint. Since then,
passengers say they have had respiratory problems,
severe headaches, vomiting, bowel problems and extreme
fatigue, the complaint says.
"The events alleged in these two lawsuits occurred more
than two years ago," said Dick Schleh, a Boeing
spokesman. "We don’t yet know anything about the facts
and circumstances surrounding the flights at issue in
these lawsuits because the operators of the subject
aircraft never reported anything unusual to Boeing."
The suit involving the charter flight also names as
defendants aerospace concerns Hamilton Sundstrand Corp.
and its parent, United Technologies Corp., and AAR Parts
Trading Inc., a subsidiary of AAR Corp.
"As a matter of policy, we do not comment on pending
litigation," said Matthew Perra, a United Technologies
spokesman. A spokesman for AAR Corp. said the company
doesn’t comment on pending litigation. The charter
flight was operated by XL Airways, a unit of XL Leisure
Group PLC, which ceased operating last year. A
representative for the company, which wasn’t named in
the suit, couldn’t be reached for comment.
Mr. Schleh, the Boeing spokesman, said that, in general,
when bleed-air contamination occurs, "levels of these
compounds of contaminants are low."
He added that air on planes is healthy, safe and exceeds
air-quality standards. Still, Mr. Schleh said, "Boeing
is supportive of additional research" into bleed-air
contamination.
How often bleed-air contamination occurs is unclear. A
British government committee studying the matter
estimated that fume events happen on 1% of flights,
based on pilot reports. But it found a much lower rate
of incidence '0.05% of flights' from studying airline
maintenance reports. Those data suggest that between 14
and 279 flights that take off in the U.S. each day might
experience a fume event.
Between 1999 and 2008, the FAA recorded over 900 fume
events. But some airline-worker unions believe that
contamination events are underreported by airlines and
pilots. The event on the US Airways flight in March, for
example, wasn’t reported to the FAA.
Mr. Durrant, the US Airways spokesman, said the airline
believes "an unpleasant smell in the aircraft does not
warrant reporting to the FAA. If it was smoke, we
would."
There is no reporting system in place to track people
with symptoms they suspect stem from contaminated
airplane air.
In 2003, Congress asked the FAA to fund research on
bleed-air contamination. The research team, made up of
academic scientists and union officials, collected air
samples from 63 flights and collected health
questionnaires from about 4,000 flight attendants.
The group recently turned its findings over to the FAA
for review before they are released publicly.
Researchers found low levels of tricresyl phosphates in
some of the air samples taken, but generally the results
were inconclusive, largely because of the small number
of samples gathered, says Steve Hecker, a director in
the department of environmental and occupational health
sciences at the University of Washington and principal
investigator for the study.
The FAA says other research it is conducting includes
analyzing contaminants in aircraft filters and
developing sensor technology that could be used to
monitor onboard air.
Inconclusive Evidence
British regulators studied cabin air quality following
complaints from a pilots union. In a 2007 report, the
Committee on Toxicity of Chemicals in Food, Consumer
Products and the Environment said that "it was not
possible on the basis of the available evidence?...to
conclude that there is a causal association between
cabin air exposures and ill health in commercial
aircraft crews."
But the report said "that an association was plausible"
based on the timing of contamination exposures and
reports of acute health symptoms. Another study in
Britain and one in Australia are under way, with results
due out next year.
While scientific data don’t conclude that bleed-air
contamination has negative health effects, flight crew
representatives say evidence is sufficiently compelling
to warrant companies taking action. It is "more probable
than not that inhaling engine fumes is making people
sick," says Tristan Loraine, a former British Airways
captain who co-chairs a London-based committee that
represents airline workers on cabin air-quality issues.
Mike Holland, an American Airlines pilot and deputy
chairman for radiation and environmental issues at the
Allied Pilots Association, says the union recently began
alerting members to the possible dangers of contaminated
bleed air. He makes a point, for instance, of contacting
American Airlines crew that he thinks might have been
exposed to contamination based on pilot’s logs and
maintenance records. He advises them of what symptoms to
look for, including dizziness or difficulty breathing,
and hands out a guide aimed at familiarizing medical
providers with bleed-air contamination.
There isn’t much passengers can do if they are concerned
about bleed-air contamination. The drop-down oxygen
masks on a plane provide, in part, recirculated cabin
air, although pilots and flight attendants have access
to pure oxygen.
Airline-worker unions have suggested putting carbon or
other filters into bleed-air systems to trap
contaminants before they enter the cabin. But technical
experts say that adding filters would require major
engine adjustments to keep the correct amount of air
flowing into the cabin and maintain fuel efficiency.
There are "many, many things you would have to think
about before doing something like that," says Andreas
Halske, an engine expert and propulsion system engineer
at Lufthansa Technik AG.
