Wall Street Journal

WALL STREET JOURNAL

Polar Flights to Asia Raise Health Concerns

By ZACH COLEMAN  Staff Reporter of THE WALL STREET JOURNAL

The start of two nonstop flights between Hong Kong and New York over the next two months will shave about two hours off that long, grueling journey.

That is something I am looking forward to after making the trip myself via Chicago last month. The new flights, operated by Continental Airlines and United Airlines of the U.S., have become possible after Russia this month opened up commercial routes over the North Pole. Because of the Earth's shape, flying over the pole is significantly shorter than the traditional trans-Pacific routes. 

But the way may not be as clear. Cosmic radiation, of little concern on the ground, is much stronger at high altitudes over the poles. And because these flights will be the longest commercial routes in operation, they also raise the issue of deep-vein thrombosis, or "economy-class syndrome," which has sprung to world-wide notice following the death of a young British woman who collapsed and died in London following a Qantas Airways flight from Sydney in October.

Cosmic radiation is made up of high-energy subatomic particles bombarding the Earth from the sun and other stars. Although many researchers minimize the significance of in-flight radiation as compared with other cancer-causing agents in the environment, some studies have found higher incidences of cancer among pilots and flight attendants. A number of governments in fact classify flight crews as radiation workers, and in May, the European Union put in rules requiring airlines to track and limit radiation exposure. 

Because of the way the Earth's shielding magnetic fields are shaped, radiation levels over the poles are up to three times greater than levels at the equator, according to researchers. And 11 kilometers up, about where jumbo jets cruise on long-haul flights, cosmic radiation is 117 times more intense than at sea level at Hong Kong's latitude. Those radiation levels can soar far higher during solar flares. 

With all that, the radiation exposure on the New York-Hong Kong flight would add up to the equivalent of close to four full chest X-rays. Robert J. Barish, a medical physicist in New York who wrote a book titled "The Invisible Passenger: Radiation Risks For People Who Fly," calculates the exposure on a flight over the North Pole at about 0.18 millisievert (mSv) each way. That is just under one-fifth of the one-mSv limit on exposure a year for the general public in the U.S. The limit for radiation workers, presumed to be aware of, and consenting to their exposure, is 50 mSv. But because of potential dangers to a developing fetus, the International Commission on Radiological Protection limit for pregnant radiation personnel is two mSv, equivalent to 5.5 round trips on a polar route. 

"This is certainly an issue for pregnant flight attendants and pilots, and it may be so for other pregnant frequent flyers if they must make a trip like this every few weeks," says Dr. Barish. But generally, he believes the shorter flight time will balance out the greater intensity of the polar radiation on the new flights. 

Northwest Airlines, which has been operating polar flights on a test basis from Detroit to Beijing and Shanghai since 1998, checks solar radiation levels measured by the U.S. National Oceanic and Atmospheric Administration, reported daily on the agency's Web site, according to a spokesman. Northwest has twice rerouted flights because of excessive radiation levels during increased solar activity. United, which has also been operating test polar flights, says it provides general exposure information to its crew. But a spokeswoman for Continental, which will inaugurate polar routes March 3, takes the surprising stand that passengers and crew can seek out their own information about the potential health risks of in-flight radiation exposure.

Continental takes the same stance with regard to deep-vein thrombosis, or DVT, which occurs when a blood clot forms in the legs during a long period of inactivity, such as during a long flight or car trip. The clot can be fatal if it reaches the lungs or other vital organs. News reports out of Japan, Australia and the U.K. have suggested that the death toll in recent years from DVT -- not necessarily related to long flights -- ranges from dozens to the thousands. Hundreds of Australians have signed up with a firm there that has filed a lawsuit against a large group of international airlines.

 Several airlines have been spurred to action. Singapore Airlines has started putting information about DVT on a seat-back card, along with tips on in-seat exercises to keep the blood flowing through the legs; United and Qantas have put similar information in their in-flight magazines. Australian and New Zealand carriers plan to provide information upon ticketing as well. The International Air Transport Association issued "precautionary guidelines" Thursday to its member airlines, suggesting that "At the time of reservation, travelers should be informed of the risks of DVT." 

General advice on avoiding DVT on long flights includes wearing loose-fitting clothing, drinking plenty of nonalcoholic beverages and doing leg exercises. One issue of contention is whether passengers should walk around the cabin, seemingly the easiest form of leg exercise; United, Singapore and Qantas are recommending regular walks but IATA says passengers shouldn't be encouraged to walk around "as this could compromise safety in the event of unexpected turbulence."