A few tips for your next flight

By KAREN HOLDOM

Many travellers believe airline cabins are fetid places, swarming with viruses and bacteria.

But Marc Shaw, medical director of Auckland's Worldwise Travellers and Vaccination Centre, says constant recirculating and efficient filtering actually makes cabin air relatively sterile.

So why do so many people suffer colds and flus after long flights? The most likely, but not scientifically proven, explanation is that the stress, fatigue, temperature and time zone changes which go hand in hand with travel temporarily weaken your immune system — making you more vulnerable to any bug which crosses your path.

To reduce your risk, says Shaw, try to be well-rested in the days leading up to a flight, and be as organised as possible to prevent last-minute stress.

Regular exercise and a nutritious diet will improve your general health, and going to bed an hour earlier for a few days before changing time zones can help your body clock to prepare for the upheaval ahead.

Dressing warmly for the flight can protect you against the cool temperatures at maximum altitude.

The most serious health risk from flying comes if you've had major surgery or certain types of dental treatment in the fortnight leading up to your flight. The cabin pressure can be dangerous. Check with the doc first.

Another risk, although relatively low, is deep vein thrombosis — potentially lethal blood clots which form in your cramped lower legs.

Those most vulnerable are people with existing thrombosis, varicose veins and heart conditions.

Travelling business class, where there is more leg-room, will reduce the risk but a simple pair of support stockings is a far cheaper if more embarrassing option. Your doctor may also recommend you take half an aspirin before flying to thin the blood.

Fluid replacement is the health issue affecting all passengers. People don't actually get dehydrated on flights but fluid pools in the legs and feet, starving the organs and blood vessels and causing symptoms like disorientation. To prevent this, Shaw recommends a fluid intake of 750ml to one litre for every eight hours of flying.

While others preach on the evils of alcohol at altitude, he's refreshingly realistic.

"Alcohol is essential for any flight because it's free," he says with a grin.

"Provided people remember that, firstly, it's two to three times more potent at altitude and secondly, they follow it up with glasses of water every hour."