What really happens to your body on a flight

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From oxygen deprivation and cosmic radiation to loss of taste, your body can suffer some worrying effects during air travel. But how can they be avoided?

You’re nearly 100 times more likely to catch a cold

There’s nothing more discomforting than sitting alongside a sneezing, wheezing traveller in cramped quarters for hours on end. Recent studies might have you believe that these fears are well founded.

Researched compiled by Comparetravelinsurance.com.au recently claimed that the likelihood of catching a cold is more than 100 times higher during a flight.

Dr Richard Dawood, Telegraph Travel’s travel health expert, says the “virtually moisture-free” conditions inside a plane cabin increase your vulnerability to airborne infection . You’re more susceptible to colds and respiratory infection, and viruses which are known to thrive in conditions of low-humidity.

“Coughing passengers can spread infection to those immediately around them, and in a small number of cases of more severe illnesses – such as TB [tuberculosis] – are known to have spread in this way,” said Dr Dawood.

The total volume of air on a plane is said to be refreshed every two to three minutes, which – according to the Civil Aviation Authority – is more frequent than in most air-conditioned buildings, where the air is changed every five to ten minutes.

Airlines, of course, tout their cleanliness. British Airways told Telegraph Travel it has “extremely high standards” with its planes being “thoroughly cleaned after each and every flight, including the seats, tray tables and aircraft toilets”.

Contamination

The findings of Auburn University in Alabama in 2014 revealed that disease-causing bacteria can survive for up to a week inside plane cabins, on surfaces such as seat pockets, tray tables, window shades and armrests. Staphylococcus aureus (MRSA), a bacteria that could cause infections, skin disease, pneumonia and sepsis, lived the longest (168 hours). Escherichia coli (E. coli), which can cause urinary tract infection, respiratory illness and diarrhoea, was found to survive for 96 hours.

Water stored on planes has been found to contain traces of E. coli and other harmful bacteria, according to recent research .

CNN, back in 2010, highlighted six key “germ zones”, perhaps the most surprising of which was the on-board water. It cites a 2004 study that saw water samples taken on board 327 different domestic and international aircraft. Some were found to have contained E. coli. Coffee and tea are brewed using this water, it said, but don’t typically reach hot enough temperatures to kill E. coli.

More worrying still, it claimed that when bottled water runs out, some crew members have been known to fill passengers’ glasses from the tank. Some planes were also said to sometimes refill their water tanks at foreign airports, where the water quality may not be so reliable.

Lavatories, it will come as no surprise, were also highlighted as areas of concern (or “smorgasbords of threat”, to be precise). The US Centre for Disease Control (CDC) named the lavatory as one of the crucial “hot zones” for spreading diseases during the outbreak of the H1N1 and severe acute respiratory syndrome (SARS) viruses. The “thunderous volcanic” flushing action of the toilet exacerbates the health risk by launching germs from the toilet in all directions.

A report by The Wall Street Journal, back in 2007, claimed that airlines washed their blankets only every five to 30 days.

Oxygen deprivation

Aircraft cabins are pressurised to 75 per cent of the normal atmospheric pressure, a recent study claimed . Lower levels of oxygen in your blood can lead to hypoxia, which can leave you feeling dizzy, fatigued and with headaches.

Aircraft manufacturer Boeing is adamant that cabin air is safe to breathe. “Research has consistently shown that cabin air meets health and safety standards and that contaminant levels are generally low,” Matt Knowles, a spokesperson for Boeing, told Telegraph Travel.

“High efficiency particulate air (HEPA) filters are used to remove particulate matter from the recirculated air including bacteria and viruses. The HEPA filters are used to filter about 50 per cent of the air in the cabin and this reduces the concentration of germs by about 50 per cent,” he said.

Perhaps the biggest health risk on a plane is when a flight is delayed and ventilation systems are turned off.

“Some of the best-known instances have occurred on the ground – such as a large flu outbreak following a prolonged delay on the ground – with ventilation systems switched off,” Dr Dawood told Telegraph Travel.

Loss of the ability to taste and hear

A third of your taste buds are said to become numb at high altitudes, while dryness and cabin air pressure also affect your ears, sinuses and sense of taste, according to the latest research .

Cold temperatures, grey cabin lighting and high stress levels were also found to dull passengers’ tastes of food, according to a previous study carried out by British Airways and the Leatherhead Food Research .

Bland airline food comes from the result of dry cabin conditions and high-altitude pressure that appear to suck the flavours out of food.

To counter this, British Airways looked to Japan, which has long extolled the virtues of umami, known as the “fifth basic sense” alongside sweet, sour, salty and bitter. Discovered in 1908, the distinct taste was found to be the key savoury factor in foods such as tomatoes, meat and other foods, prompting the airline to source more umami-rich dishes in its meals.

Cosmic radiation

Passengers are exposed to nearly the same dosage of radiation as an X-ray on a seven-hour flight from New York to London, recent research claims .

Last year, the Government feared long-haul air passengers could be at risk from dangerous cosmic rays coming from the sun and issued an “urgent” investigation into the effects of increased solar radiation huge amounts of magnetically charged particles are thrown out into space, in what is known as a Coronal Mass Ejection .

The report by Public Health England (PHE) warned that a solar storm was “most likely to affect the general public if they are travelling by air on trans-oceanic routes.”

The investigation came as new Nasa-funded research found that solar storms could trigger showers of harmful radiation which could cause health problems not just in the air, but also at ground level.

Dehydration

Your body is said to be deprived of up to 1.5 litres of water on a three-hour flight, according to the latest research, and humidity levels as low as four per cent has the potential to cause the mucous membranes of your nose, mouth and throat to dry out.

Bloating and swelling

Air pressure changes cause a build-up of gas in your body, which leads to bloating, constipation and other related gastrointestinal issues. Meanwhile, the lack of movement during a flight could cause the build-up of blood around the legs, heightening the risk of getting deep vein thrombosis.