Adjusting Cabin Pressure Eases Air Passenger Discomfort

WEDNESDAY, July 4 (HealthDay News) -- The discomfort some passengers feel on airplanes could be due to the air pressure settings inside cabins, a new study finds.

Most aircraft cabins are pressurized to 8,000 feet above sea level, an altitude that lowers the amount of oxygen in the blood by about 4 percentage points, researchers say.

This decrease in oxygen saturation isn't enough to bring on acute mountain sickness, but pressurizing the cabin to 6,000 feet could help some passengers feel better when flying, concludes a study in the July 5 issue of theNew England Journal of Medicine.

"We found that the altitudes did not affect the occurrence of acute mountain sickness syndrome, but it did affect discomfort," said the study's lead author, Dr. J. Michael Muhm, senior occupation physician for Boeing Commercial Airplanes in Seattle, which funded the study. "There was no difference in the likelihood of discomfort at ground level and 6,000 feet, but the likelihood increased between 6,000 and 8,000 feet."

He added, "We concluded that passenger and crew comfort would be enhanced" if the cabin was pressurized to 6,000 feet during long-duration flights.

Most commercial aircraft are pressurized to 6,000 to 8,000 feet, not sea level.

"In order to pressurize at ground level, we would have to increase the weight of the aircraft tremendously, because the material as it exists right now couldn't tolerate pressure at ground level," explained Dr. Claude Thibeault, medical director of the International Air Transport Association in Montreal. "We would have to increase fuel, decrease passengers. So, it's an operational sort of factor."

And 8,000 feet, the maximum allowed, is also physiologically acceptable for "normal" people, he added.

"The average Joe in good condition could tolerate 8,000 feet without health effects," Thibeault said. But he noted, "They didn't say without discomfort."

Short-haul flights are usually pressurized at 5,000 to 6,000 feet while long-haul flights are closer to 8,000 feet, according to Thibeault.

But acute mountain sickness, which can involve headache, nausea and vomiting, can occur at altitudes of 6,500 feet and higher.

The authors of the study wanted to see, among other things, if airplane travelers were prone to mountain sickness.