Air quality and plane toilets: Why flying can make you sick

The idea of aircraft as flying germ incubators where every surface is crawling with nasties, where you're breathing air that has just come from the lungs of the guy coughing and sneezing in the row behind is deeply troubling for some flyers, but is it really as bad as all that? Why do we stress about travelling on planes when most of us think nothing of commuting on a tram, bus or train? 

Leaving aside air-travel related conditions such as motion sickness, jet lag, dehydration from travelling for long periods in a low-humidity environment and deep vein thrombosis, and focusing on sickness resulting from bacterial or viral infections, what are the hazards that can  result in you spending your entire holiday lying in a hotel room with frequent bathroom visits, or worse?

See also: Dirtiest places on planes and in airports

Air quality is one issue. Unlike that commuter ride, you're trapped inside a sealed metal canister. The thought of breathing air that might be contaminated with airborne viruses worries some passengers, but the air you breathe in an aircraft cabin is scrubbed clean. What you're breathing is a mixture of fresh and recirculated air. The fresh air supply comes from the compressor stage of the jet engines. After it's cooled in air conditioning units it passes through a High Efficiency Particulate Air (HEPA) filter, which takes out all but a tiny fraction of airborne particulates, bacteria and viruses. This air is then ducted into the cabin via vents, louvres and those over-seat eyeball sockets. The air swirls around in the cabin until it exits via the lower fuselage where about half is vented overboard, The remainder is mixed with a fresh incoming supply from the compressors,  passed through the HEPA filter again and recirculated. It's also fast. Cabin air in a modern jet aircraft is completely refreshed every two to three minutes, much quicker than in a typical office, classroom or hospital, and way more frequently than in a bus or train carriage. Getting sick from an airborne pathogen is about the least of your inflight medical worries.

There are a couple of other major points of difference between an aircraft cabin and the train or bus carriage we might use every day. We're not likely to eat on our commuter ride, nor are we going to use a toilet since there probably isn't one. 

Aircraft toilets are where hygiene takes a holiday. On a long flight each toilet on an aircraft might see individual visits numbered in the hundreds. Aircraft toilets are typically small, they might be moving around in air turbulence and this limits the ability of passengers to deal with their waste in a thoroughly hygienic manner. Also, sinks are tiny, and the water supply more a sprinkle than a gush, making it difficult to wash your hands effectively. Even medical doctors as a whole are not great at hand hygiene, much worse than nurses according to the Medical Journal of Australia, so what hope for the rest of us? If the previous passenger was infected with norovirus, a virulent, highly infectious pathogen that can cause violent eruptions at both ends and if they failed to wash their hands thoroughly, just pushing the release mechanism on the toilet door might be enough to bring you undone. 

It's important to keep yourself well hydrated, and that makes toilet visits inevitable on a long flight but you're usually better off visiting the airport toilets close to flight time rather than those on the aircraft. On the same issue, shoes are the correct footwear for toilet visits, barefoot or socks only is a really bad idea. You wouldn't wade into a public toilet barefoot, and the same applies on an aircraft. 

See also: Travel health tips: 15 ways travellers get sick

Water from the aircraft tank is not guaranteed pure since there is a chance that the tank has been refilled at an airport where the water supply is not fit for human consumption. That's the reason there is a warning against drinking the water that comes from the tap inside the aircraft toilet. Tea and coffee served on board might be made using this water, and brewed at a temperature lower than the 75 degrees required to eliminate E.coli, that feisty gastrointestinal  gremlin. Stick to drinks from cans and bottles. If you're worried about the sugar content, or the alcohol, soda water is a zero calorie substitute, and you might want to specify no ice. 

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Eating on aircraft carries its own set of risks, not just from the overcooked veggies but from the bacteria and viruses that you might introduce via your mouth. 

Rhinovirus, the most common virus responsible for colds, as well as the 200-plus other strains of virus that cause colds, can survive for many hours in an aircraft environment. Methicillin-resistant Staphylococcus aureus  (MRSA) is a bacterium spread by contact and which can cause sores or boils, or more serious complications if it gets into the bloodstream, the lungs or the urinary tract. MRSA can survive for a week in an aircraft environment. E. coli can live for four days. Passengers carrying these bacteria and viruses might have been occupying the seat you're now sitting in, using your remote control for the video screen and eating from the same tray table that you've just flopped open. Even in passing they might grab armrests or seat backs, and that opens the possibility of transmitting whatever it is they're carrying. 

In order for MRSA, norovirus or any other pathogen to become active and start gnawing at your organism it has to get from your hands or via some other contaminated vector into your mouth. This is most likely to happen when you're eating or drinking, and this is where you can introduce a circuit breaker. The solution is to use a hand sanitiser gel with at least 60 per cent alcohol. 

Some of the more diligent flyers advocate swabbing your tray table, your armrest and anything else you touch with antiseptic wipes. While that will help keep you safe it also creates a problem. The antibacterial agents triclosan and triclocarban commonly used in these wipes and also in antibacterial soaps are the ones that result in beefier bacteria, the antibiotic resistant superbugs. In the long term these products are doing us more harm than good. An alcohol-based gel is a much better solution if you want to keep your hands absolutely clean, and your travel plans intact.

See also: How to avoid germs on planes

See also: What happens when there's a medical emergency on a flight?

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