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The New York Times

Radiation Exposure Seen as Posing Risk For Airplane Crews

 

By MATTHEW L. WALD

Correction Appended

Pilots and flight attendants on many airline routes are exposed to more radiation than most workers in nuclear power plants, new Government studies show. In power plants the Government imposes extensive safety requirements, including education, monitoring and procedures to minimize dose, but no such limits are applied for the flight crews.

Concern over radiation from the sun and the stars for both flight crews and passengers was stated more bluntly than ever in a report made public Monday by the Department of Transportation.

For airline personnel, the report likens the level of risk to that from working in cabins filled with cigarette smoke. The report also noted a higher risk to ''very frequent fliers'' on long trips and to women in early pregnancy.

Although scientists emphasize that the effects of low doses of radiation are uncertain and nearly impossible to measure in the population, several conclusions are clear from the report, as well as from the draft of a warning published late last year by the Federal Aviation Administration and from research by experts outside the Government.

Aviation officials have rejected requiring protective measures but may do so now. The new studies seem likely to spur further action, though airline employee unions are split on the importance of the issue.

The radiation doses received by the flight crews vary with the altitude and latitude: the higher the plane is flying and the closer to the poles, the higher the radiation doses. Experts say no shielding would stop the very-high-energy radiation to which air travelers are exposed, but monitoring devices in the cockpit could warn when it would be helpful to fly at a lower altitude to evade the radiation.

These devices would be useful because the sun's output of radiation varies widely, and a few times each decade the levels rise high enough to be of concern to women who fly just once during pregnancy.

But even for pilots and flight attendants, scientists say, the additional risk of cancer carried by the radiation exposures in flight is modest as against the overall cancer rate.

For instance, the Transportation Department study predicted that among 100,000 crew members who spent 20 years flying 960 hours a year on an east-west domestic route of more than three hours, 59 to 61 ''premature cancer deaths'' would occur. Among 100,000 passengers flying 480 hours a year on the same route, or about 9 hours a week, 29 or 30 additional cases of cancer would occur. The rate of cancer from all causes would be about 22,000 in that group. Pregnant Women Told To Avoid Some Trips Moreover, Dr. Michael E. Ginevan of Geomet Technologies Inc., of Germantown, Md., who made those calculations, said that since the report was completed in December, new findings based on cancer rates among survivors of Hiroshima and Nagasaki had tripled or quadrupled the expected incidence of cancer from low-level doses.

''If I were a woman in the critical period of pregnancy for retardation, I would tend to avoid flights to Europe,'' Dr. Ginevan said. Scientists say the most critical period is from the eighth week of pregnancy to the 15th week.

Dr. Andrew Horne of the F.A.A.'s Office of Aviation Medicine said in a telephone interview: ''We think it would be appropriate to educate people, particularly pregnant crew members who may be flying. It might be appropriate for some to consider alternate routes or leaves of absence.''

Although there is a mechanism the F.A.A. could use to warn the pilots to fly lower, during peak periods of solar activity, it has never been put in action. Exposure Can Be Higher Than at Nuclear Plants On some routes, the annual radiation doses for crews are higher than the averages for workers in a nuclear power plant, medical office or industrial setting where X-rays or radiation sources are used, the experts say.

Dr. Robert J. Barish of the division of radiation oncology at New York University Medical Center says radiation levels in a jetliner are occasionally so high that in a nuclear plant they would require signs warning of high radiation and instructing workers not to spend any longer in the area than necessary to do their jobs.

Concern among scientists is rising, because in the last few years researchers have doubled their estimate of the damage to cells caused by neutrons. These sub-atomic particles are prevalent at high altitudes.

In addition, planes today fly for longer periods at higher altitudes, with less of the atmosphere to shield them from cosmic sources of radiation, specialists say. The Concorde and corporate jets, which fly even higher than standard passenger planes, are especially vulnerable. More and more planes fly between North America and Asia or Europe over the North Pole, where radiation levels are four times those at the equator because of the effect of the Earth's magnetic field.

Dr. Barish said some sort of forecasting was needed, for example, to help pregnant women decide whether to fly on a particular day. Solar radiation peaks every 11 years, and at a handful of times in the cycle radiation fields are so high, he noted, that the dose on a single flight can exceed the recommended monthly maximum for a fetus.

While there are no statistics demonstrating a link between exposure to such low levels of radiation and illness and death, the Federal radiation standards are based on the theory that any dose of radiation is harmful - that there is no quantity so small that it is harmless. Doses Exceed the Limits Set by the Government Scientists say the radiation doses are far too low to cause acute illness even for crews flying the most vulnerable routes. But figures compiled by the F.A.A. show that over a year, the doses accumulated by airline crews on some routes exceed the guidelines set by the Government that call for employers to warn workers of a potential hazard and keep doses ''as low as reasonably achievable.''

Dr. Edward T. Bramlitt, a Defense Department health physicist who has argued for regulation, said workers whom the Government considered to be occupationally exposed are informed of the risks, and their employers required to keep records of workers' exposures.

Some airline unions have raised concerns about exposure to radiation. ''The cancer risk they're describing is not an insignificant risk,'' said Matthew H. Finucane, director of air safety and health at the Association of Flight Attendants. ''They need to regulate this area.''

Each airline sets its own rules on how long pregnant crew members can work, but Mr. Finucane said that none refer to radiation exposure.

But officials of major airlines and their trade association say they do not believe that radiation should be a priority issue, and some employees' representatives agree.

''In terms of actual known risk, the F.A.A. has a lot more pressing problems than this one,'' said Dr. Donald E. Hudson, of the Air Line Pilots Association's aeromedical office, in Denver, Colo., citing aircraft maintenance and crowded flight patterns.

Dr. Hudson said radiation risks are not the biggest health problems for pilots; he ranked heart disease higher.

Dr. Barish wrote and published a book on the subject and has developed an instrument for measuring radiation aloft, which he is seeking to sell. He said that the Government should force airlines to monitor radiation doses and provide information on the risks, as is done with nuclear power plant workers. F.A.A. Is Reviewing Precautions for Crews But the Federal Aviation Administration decided in March 1986 not to classify members of cabin crews as radiation workers, the agency said, because the agency said at that time that few crew members would receive a dose higher than the amount that Federal standards say the public should be exposed to.

That limit is stated in a unit called millirem. The recommended limit for people in non-nuclear fields is 500 millirem a person a year.

But the aviation agency acted before scientists made public their most recent findings about neutrons, greatly increasing the estimated doses encountered by flight crews. With the new estimates, many cabin workers exceed 500 millirem a year in the air, the agency now acknowledges. According to Dr. Jon L. Jordan, the Deputy Federal Air Surgeon, the agency is reviewing its position as to precautions for people who work aloft and whose doses exceed 500 millerem.

And the Federal standard may soon be lowered. The National Council on Radiation Protection and Measurements recommended to the Federal Government in 1987 that the maximum allowable dose to the general public be lowered to 100 millirem a year. Jobs that bring exposure above the limit for the general public are supposed to be governed by occupational rules.

The aviation agency's draft warning said that crew members would accumulate 910 millirem a year working the Athens-New York route, a flight lasting more than nine hours, with altitudes up to 41,000 feet.

Doses for flights at lower altitudes and latitudes closer to the equator were lower; from New York to Minneapolis, for example, the figure was 500 millirem, and from Houston to Austin, 20 millirem.

In contrast, the Environmental Protection Agency says nuclear plant workers get an average of 650 millirem a year. The average dose to residents of the United States from natural and man-made sources is about 315 millirem a year; a chest X-ray is 10 millirem. Planes Could Fly Lower During Solar Outbursts The warning counts only radiation from the stars, which is constant. A more variable source, and one that is at times more important, is solar storms linked to sunspots. These release streams of protons, sub-atomic particles that can produce doses thousands of times the usual, Dr. Barish said.

On Sept. 29, 1989, a storm briefly produced a dose at 65,000 feet near the poles of 110 millirem an hour, he said in a paper being reviewed for publication in the journal Health Physics. Yet Government guidelines for pregnant women limit exposure to 50 millirem a month. The standards are based on studies showing damage at higher levels and scientific projections about the effects at lower levels.

The National Oceanographic and Atmospheric Administration, which monitors solar flares by satellite and issues a daily forecast, warned the Federal Aviation Administration of the radiation at the time of the Sept. 29 storm. But the event ended before the agency passed the warning along, and most experts say pilots would not have known what to do with the information anyway.

For intense solar outbursts, scientists say, the solution is to fly lower. Dr. Barish said the effect varies by latitude, but usually flying 6,000 feet lower would halve the dose.

But doing so would reduce speed and fuel efficiency.

Counting only the radiation from the stars but not from the sun, the F.A.A. warned that if 1,000 crew members spent 20 years flying between New York and Minneapolis, the radiation dose would be expected to cause three fatal cases of cancer. The draft is being revised, said Dr. Wallace Friedberg, who led the team that wrote the warning, to take into account the study issued in December by the National Academy of Sciences that says the cancer risk from low levels of radiation may be three to four times what had been believed.

Scientists note that even if the number of cancer cases predicted in the warning was multiplied by 3 or 4, to 9 to 12 cases among 1,000 crew members after 20 years, the number would still be modest as against cancer incidence due to other sources.

Dr. Anthony B. Wolbarst of the Environmental Protection Agency said that accepting the idea that there is no safe dose is prudent in the face of uncertainty.

Of the dose estimated for the New York-to-Athens route, Dr. Wolbarst said: ''I think the risks are relatively small compared to the kinds of risks one faces in the world, and it is not horrifically unconscionable. But if they are occupationally exposed, they should be treated as such.''

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TIME MAGAZINE

Skin Cancer Risk Is Higher For Flight Attendants and Pilots

Justin Worland

Sep 03, 2014

 

TIME Health

For more, visit TIME Health.

Pilots and flight attendants are twice as likely to suffer from the skin cancer melanoma when compared to the general population, according to a new Journal of the American Medical Association study.

Looking at data compiled from more than 260,000 people in 19 previous studies, the paper expanded upon past research that has suggested that flight crews are at a heightened risk for melanoma. The cancer, which kills nearly 10,000 Americans each year, is the most deadly variety of skin cancer in the United States.

The study suggests that occupational hazards like getting more exposure to UV radiation may contribute to the increased incidence of melanoma. The intensity of UV radiation increases by 15% for about every 3,000 feet above sea level, and planes regularly fly at 35,000 feet above sea level or higher.

For years, federal authorities have kept close track of ionizing radiation that could cause other cancers, but there has been little consideration of UV radiation. The study notes "important implications" for flight crew members, but doesn't provide recommendations for policymakers.

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Sports Illustrated

Why Chris Bosh could miss the rest of the NBA season with blood clots

DR. PETER C. VITANZO, DR. BARRY E. KENNEALLY

Miami Heat forward Chris Bosh is currently being evaluated to see if he has blood clots in his lungs that may cause him to miss the remainder of the NBA season, Joseph Goodman of the Miami Herald reports.

 

Bosh was sent to the hospital after reporting for practice Thursday feeling "under the weather," according to head coach Erik Spoelstra. The team didn't reveal the nature of the testing, but the Herald reported that initial tests focused on Bosh's lungs. A Heat spokesman said initial testing was inconclusive.

 

Blood clots in the lungs can be dangerous and even deadly. These clots typically form in the legs as a deep venous thrombosis (DVT). Our blood naturally forms clots to allow our bodies to heal and stop bleeding after injuries. However, they can form unexpectedly and without any type of notice. This typically occurs in veins in the legs or arms as DVT. Often patients with this condition can develop leg swelling (sometimes painful), warmth, and a reddish or bluish discoloration.

 

The major fear with this kind of condition is the possibility that a piece of the blood clots may break off and travel through the bloodstream and lodge themselves in the lungs, which can result in pulmonary embolism (PE). Symptoms associated with PE can include chest and/or back pain, acute shortness of breath, exhaustion or unexplained fatigue, dizziness, and even fainting. More troublesome are the patients that don't exhibit any symptoms with this condition, which means tragedy can strike without warning.

 

Pulmonary embolism is very common, affecting about 300,000 Americans each year. The condition is more common in people who are inactive but can often occur in athletes as well. Many people actually have genetic traits that predispose them to forming these types of clots. In addition to Bosh, several other professional athletes are known to have dealt with PE including the NHL's Kimmo Timonen, Jed Ortmeyer and Pascal Dupuis, the NFL's Jason Pinkston, Serena Williams, while Anderson Varejao and Mirza Teletovic have both been diagnosed with the condition in recent years.

There are several risk factors that are unique to professional athletes in regards to blood clots.1–3 Strenuous exercise or trauma can cause damage to blood vessels and clots can form at those damage points. Immobilization after a strenuous workout or injury can allow blood to pool and form clots. Dehydration after exercise thickens blood and can allow clots to form. Air travel (especially prolonged flights) has long been known as a risk factor for blood clots. Part of this is due to the immobilization of sitting still for the flight and the blood pooling in the legs and not getting pumped back to the heart as easily because the leg muscles are not being used. Since professional athletes are forced to fly (often long flights) more than most of us during their respective seasons, this is a significant risk for them.

 

In addition, athletes often suffer higher rates of injuries that require immobilization and/or surgery that can also increase their risk of blood clots and possible PE. Athletes may face a slightly increased risk of forming blood clots but this is mainly a problem for those rare athletes who have a genetic predisposition to forming clots.

There are medications that can be used to thin the blood in people who form DVTs or PEs. These are typically taken for several months after a clot is diagnosed, which is why Bosh's season could be in jeopardy if he's found to have the condition. When taking blood thinners, patients tend to bleed more when injured, which can be problematic for athletes in contact sports, like basketball. That's why you'll see athletes sidelined up to six months or more while they're being treated—arm or leg injuries tend to be more severe, but injuries to the head, chest, or abdomen can be fatal.

 

Dr. Peter C. Vitanzo is a sports medicine physician at the Rothman Institute who also works with the Phillies, 76ers and several collegiate sports teams in the Philadelphia area.​ Dr. Barry E. Kenneally, also a sports medicine physician at the Rothman Institute, treats a wide variety orthopedic problems in athletes and non-athletes.

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FAST COMPANY

Why Frequent Business Travel Is So Bad For You

Those frequent business trips are slowly killing you. Here’s why and what you can do about it.

We all have them. Heck, maybe you are one of them. Those Facebook friends who get to travel all over the country or the world for their jobs. Instead of being stuck in the same office day after day, frequent business travelers are taking three or four business trips a month. While you’re annoyed by Kim from accounting’s smelly lunch, your frequent business traveler friends are checking in at LAX, PEK, DXB, and LHR. They’re posting Instagram snaps of the view of the cherry blossoms from their hotel room in Tokyo or of that excellent escargot from that little cafe along the Champs-Élysées, all on their company’s dime. They really are living the life, it seems–or are they?

According to Scott Cohen, deputy director of research of the School of Hospitality and Tourism Management at the University of Surrey, it’s time to send your envy packing. Cohen recently published a paper titled A Darker Side of Hypermobility, in which he aggregated the data from 15 years of major studies on frequent travel. His findings are nothing short of disturbing if you’re one of what Cohen calls the “hypermobile”: “a mobile elite who are often well connected to global networks, with their lifestyles closely but not exclusively linked to the practice of business travel.”

In Cohen’s review of the literature, he found that this mobile elite, instead of bragging about their exciting lifestyles, should be very concerned about their health. “[Business travel] has a wide range of physiological, psychological and emotional, and social consequences that are often overlooked, because being a ‘road warrior’ tends to get glamorized through marketing and social media,” says Cohen. He argues that this glamorization of hypermobility–used to sell flights, frequent-flyer memberships, and hotel rooms–has silenced the negative health effects frequent business travelers expose themselves to. Specifically:

FREQUENT BUSINESS TRAVELERS AGE FASTER

Scientists now understand that specific genes can affect how quickly we age–and it appears the more someone travels, the faster they age.

“Frequent flying can lead to chronic jet lag, which can cause memory impairment and has been linked in studies to disrupting gene expression that influences aging and the immune system, and increased risk of heart attack or stroke,” says Cohen.

 

THEY’RE EXPOSED TO MORE RADIATION THAN IS CONSIDERED HEALTHY

If aging faster isn’t scary enough, it turns out that frequent business travelers are exposed to more radiation than is considered healthy. “Radiation exposure is hundreds of times higher at high altitude than at ground,” says Cohen.

Matter of fact, it’s so high that “there have been calls to classify frequent business travelers as ‘radiation workers,’” he says, and notes that just seven round-trip flights a year from New York to Tokyo (about 85,000 miles) exceeds the limit for public exposure to radiation. As Cohen notes in his paper, “radiation exposure amongst commercial aircrew even exceeds that of nuclear power workers.”

 

THEIR IMMUNE SYSTEM IS WEAKER

No matter if you’re in economy or first class, everyone on a long-haul transatlantic flight is breathing the same recirculated air. Not only does this expose frequent business travelers to germs more often, the jet lag and general tiredness from running to and from airports “can even switch off genes that are linked to the immune system,” Cohen notes in his paper. This means frequent travelers are not as well equipped to fight off disease as people who travel less frequently.

THEY’RE MORE OUT OF SHAPE AND AT RISK FOR OBESITY

Unsurprisingly, those who travel a lot generally don’t have the chance to eat meals prepared with fresh, healthy foods. Airline foods are packed with salt and sugar so they can retain their taste at higher altitudes during long journeys. But that salt and sugar will wreak havoc on your body over the long term. Cohen says the poor diet, combined with a general increase in alcohol and the lack of exercise opportunities while traveling, means frequent travelers have higher risk of obesity.

 

THEY HAVE HIGHER RISK OF MENTAL HEALTH ISSUES, TOO

“The disruption of the circadian rhythm from jet lag affects mood, judgment, and concentration for up to six days,” says Cohen. In his review of the literature, he found that the cumulative effect of the stress from preparing for a trip and the jet lag from those trips can lead to “travel disorientation.”

“There is the stress of preparing for a trip, the fact that the time spent traveling is rarely offset through a reduced workload, and the anxieties of ‘inbox overload,’” says Cohen. “Stress is compounded through weather delays, technical failures, increased security checks, and rising anxieties over terrorism and safety.”

Frequent business travelers often also feel lonely and isolated–as well as guilty for leaving family members behind. Their spouses, in turn, often feel resentment and anger. When you combine the stress with the isolation and guilt, it can lead to serious mental health issues, notes Cohen. “One study found that employees of the World Bank who travel frequently for work have a threefold increase in psychological claims on medical insurance as opposed to nontravelers.”

HOW TO COMBAT BUSINESS TRAVEL’S BAD EFFECTS

Before you cut up your frequent-flyer card, it’s important to note that if you take only a short business trip once or twice every few months, you’re likely to be less exposed to the risks mentioned above, says Catherine Richards, a staff scientist at the Hutchinson Institute for Cancer Outcomes Research and adjunct assistant professor at the Department of Epidemiology of Columbia University who has studied the health risks linked to business travel.

“In our study, our most robust findings were for heavy business travel–14 days or more of travel a month,” says Richards. “We found that heavy travel was bad for self-reported health, obesity, and BMI. When I say robust, I mean that there was a significant increasing trend for these health outcomes with increasing nights spent away from home.”

While that’s good news for people who travel fewer than two weeks a month, many employees don’t have that option in the increasingly globalized business world. It’s either you travel for your job or you look for a new one. But if you have no choice, Richards says there are some things both you and your employer can do to reduce the negative effects of frequent business travel.

Richards says that companies should look into employee education programs on stress management and strategies to improve diet and activity while traveling. She also says companies could offer reimbursement rates for food on the road based on the quality of the food consumed. “Either reimburse high–energy-density food meals at a below-cost rate, or reimburse healthy meals at an above-cost rate,” she says. She adds that companies could book rooms only with hotel chains that have gyms, and provide financial incentives to employees to exercise while traveling.

As for proactive steps the employee can take, Richards says the frequent business traveler should stand or walk as much as possible in the airport, avoid moving walkways and escalators, and go for a quick walk while waiting for the flight to take off instead of sitting in a chair. If your hotel doesn’t have a gym, Richards says you can also always do pushups, sit-ups, squats, and other types of workouts within the comfort of your hotel room–and be sure to pack a pair of workout clothes and go for a run or walk outside if the hotel doesn’t have a gym. Finally, she says, “Pack healthy snacks. If you leave your food choices to what you find on the road, you may be stuck with limited to no health options.”

As for Cohen, he suggests frequent business travelers explore alternative modes of transportation–such as taking the train instead of flying. “If you must fly, try to fly direct instead of taking connecting flights that will contribute more to exhaustion,” he says, adding, “feel out whether there might be an opportunity to substitute a face-to-face visit with teleconferencing–often it is necessary to meet someone for the first time in person, but after that, teleconferencing can often get the job done.”

ABOUT THE AUTHOR

Michael Grothaus is a novelist, freelance journalist, and former screenwriter represented worldwide by The Hanbury Literary Agency. His debut novel EPIPHANY JONES is out now from Orenda Books.

====================================================================

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."

 

Write to Zach Coleman at zach.coleman@awsj.com