By Bryan Corliss
More research needs to be done to determine what causes airline passengers to complain about bad air, according to a report recently issued by the National Research Council.
One simple solution would be to increase the cabin pressure, something some airlines already have done, said a University of Washington researcher on the panel that wrote the report.
That’s possible, one of the Boeing Co.’s top environmental control systems engineers said, but all the options mean burning more fuel.
And just adjusting the air pressure alone isn’t likely to solve the problem, which could be caused by any number of factors, said Boeing’s Richard Johnson. "Really, all of them need to be looked at," he said. "There’s no silver bullet that takes care of everything."
The report was delivered to Congress last month. It calls for the Federal Aviation Administration to take a more active role in determining whether the air inside passenger jets meets public health standards.
The report notes that both passengers and flight crews frequently complain about unpleasant and unhealthy air.
Some critics say the problem lies with the fact that cabin air is partially recirculated — a fact that increases jet engine performance at the expense of allowing germs or contaminants to hang in the air longer.
That’s not the case, the report said. "The use of recirculation has no detrimental effect on cabin air quality … and when combined with effective HEPA filtration, does not contribute to the spread of infectious agents in the cabin."
But while the report states that recirculation isn’t the culprit, it doesn’t point out a clear reason for bad air.
The research report lists 11 factors that could cause bad-air complaints, from germs carried on board by sick passengers to oil or hydraulic fluids that could leak into the ventilation system from the engines, to dry air that irritates eyes and noses.
The two biggest concerns, said UW environmental health professor Mike Morgan, are cabin air pressure and ozone buildup.
The pressure issue may be the easiest to solve, said Morgan, part of the 13-person panel that spent nine months studying the issue last year.
Air gets thinner at higher altitudes, which makes it harder to breathe. Airplane cabins are pressurized to combat this. But the difference between the pressure inside the plane and outside can’t be too great or the plane will burst like an overinflated balloon.
So the pressure is adjusted on a sliding scale, decreasing the higher the plane gets. Current FAA regulations say that, at the least, the air inside a plane must be pressurized to the equivalent of 8,000 feet. While most people can breathe comfortably at that altitude, some passengers with heart and/or lung diseases cannot, Morgan said. He recommends higher air pressures, more like those at 6,000 feet.
"Nothing is simple when it comes to a commercial airliner, but it can be done," he said.
However, flying at a lower altitude burns more fuel because of drag.
High ozone levels can also cause problems, the report said, including irritated noses and throats and breathing trouble.
Both Morgan and Johnson said the next step should be an FAA-directed, congressionally funded study of all the factors.
But in the wake of Sept. 11, the relative importance of cabin air quality has fallen compared to issues like airline safety, Morgan said. "And rightly so," he added.
You can call Herald Writer Bryan Corliss at 425-339-3454
or send e-mail to firstname.lastname@example.org.