by Peter Lavelle
Longer flights, bigger aircraft and fewer stopovers increase the health risks of long-haul flights, say US researchers.
Given that almost two billion people travel aboard commercial airlines every year it’s amazing more people don’t get sick on planes. In fact, air travel on per kilometre basis is the safest way to travel.
Being cramped in a seat for up to 20 hours, 10,000 metres in the air, probably wasn’t what evolution had in mind for the human body.
But being airborne for hours at a time can be a physical challenge for some people and it’s likely to become more of an issue in the future. That’s because our population is ageing and many of these people have chronic conditions that may be aggravated by air travel. Also flights are getting longer (especially from Australia), with the introduction of new long-haul aircrafts that fly 18 – 20 hours non-stop.
More than 95 per cent of people with health problems who fly say they’re not getting enough information about the risks (it’s also an area most doctors don’t know much about).
With this is mind frequent flyers and other travellers might be interested in an article published in the latest Lancet. Researchers from Georgetown University Hospital and Washington Hospital Center, Washington DC, USA, reviewed the existing medical literature on the health dangers of long-haul flights.
Jet lag
Of all air travel’s curses jet lag is the most common curse of frequent flyers.
Jet lag is a mismatch between your body’s internal night/day clock and a new day/night cycle in another time zone. Symptoms of jet lag include daytime fatigue, insomnia, decreased appetite, constipation, as well as poor physical coordination and cognitive skills.
The severity of your jet lag depends on which direction you flew in and the number of time zones crossed. Travelling westward lengthens your day (you’re keeping ahead of the sun), whereas eastward travel shortens the day (you’re travelling towards the sun). Eastward travel is harder on your body because it has to shorten its cycle to take into account reduced day time (so people travelling east find it harder to get to sleep at night). Travel westward is easier, as the body hasn’t lost any hours and can more easily adjust.
Getting used to a new time zone typically takes one day for every time zone crossed westward or 1.5 days for every time zone crossed eastward.
If you’re travelling west, researchers suggest, go to sleep one hour later and wake one hour later than usual for the three days prior to travelling. When travelling east, you should go to sleep one hour earlier and wake one hour earlier than usual for the three days before travelling.
Another way to try to avoid it is to take melatonin (0.5 –5 mg) for a few days, at bedtime at your new destination, this can help chemically re-set your body clock. A Cochrane meta-analysis of 10 clinical trials concludes it works, say the researchers. But phototherapy, intentional exposure or avoidance to bright light before you fly doesn’t work.
Cramped conditions
When you’re in a plane, most of the time you’re sitting still, in the same seat, with a limited opportunity to move around. Immobility can cause blood to pool in the deep leg veins and form a blood clot (called a deep vein thrombosis or DVT). This clot can travel to the lungs and cause breathing problems or a heart attack. Dehydration and the lack of oxygen in the cabin make it more likely.
Statistics suggest you are four times more likely to suffer a DVT on a long-haul flight than anywhere else. DVT is more likely if your flight is longer than four hours and the risk peaks if your flight is longer than eight hours. It makes no difference if you fly business or economy class, but it is more likely if you’re sitting in a non-aisle seating, passengers in these seats tend to move around less.
Your risk of DVT increases if you have cancer, a blood disorder that causes clotting or are obese. Other risk factors include a recent surgery and taking the oral contraceptive pill (this increases the risk by at least 14 times).
So what can you do? The standard advice (which is based more on common sense than science, the researchers say) is to:
- Stay well hydrated
- Reduce alcohol and caffeine consumption
- Change positions or walk throughout the cabin
- Do calf-muscle exercises during the flight;
If you’re prone to immobility use graduated compression stockings with an ankle pressure of 17 – 30 mm Hg.
If you’re in a high risk category for DVT see your doctor before you fly, they may give you an anticoagulant for the trip (such as heparin injection or aspirin tablets) although once again, there’s debate about how effective this is, say the researchers.
Less oxygen
The air at 10,000 metres above sea level (the cruising altitude of most long-haul carriers) is too thin to breathe, so cabins are pressurised at a level equivalent to 1524 – 2438 metres.
But because the cabin pressure is still significantly lower than atmospheric pressure, we breathe less oxygen than you would on the ground, this can lead to a drop in oxygen concentration in your blood of up to 5 per cent.
The longer the flight, the more your blood oxygen level drops, as oxygen breathed in isn’t replaced (extra is added to the cabin, but not enough to maintain the original oxygen level).
Most healthy people can handle this slight drop in blood oxygen concentration, though they may get altitude sickness symptoms (fatigue, headache, light-headedness, and nausea) after the flight. But if you have a pre-existing heart, lung or blood condition you may already have low blood oxygen and may not get enough oxygen throughout the flight. This is why people with certain chronic health conditions need to talk to their doctor before flying, as they may need additional oxygen or other medications for the flight.
Rule of thumb; if you can walk a distance of 50 metres and climb one flight of stairs without chest pain or severe breathlessness, you are probably okay, say the researchers. If in doubt, see your doctor.
Catching illness
Air travellers spend long periods of time in enclosed spaces with other passengers; this makes it easier for infectious diseases to spread. Colds, influenza, gastroenteritis, food poisoning, and more serious conditions like tuberculosis and SARS have all been spread during flights. But the researchers argue this danger has probably been overstated. In many cases people think they’ve picked up an infection during the flight, but in truth they caught the disease prior to getting on the plane.
The research suggests sitting next to someone on a plane puts you at the same level of risk as sitting next to someone with a cold or flu on a bus, train, or a car for the same period of time.
Air travel is not without its risks, especially if you have a chronic health condition, but there’s no need to hang up your wings. If you are a frequent flyer try to secure yourself an aisle seat, be sure to move to around during your flight and if you have a chronic health condition speak to your doctor long before you board the plane. Have a nice flight!
Source: ABC Health & Wellbeing
