If more people washed their hands properly - or at all - while at airports, the spread of diseases like COVID-19 could be vastly reduced, a recent study has found.
Researchers at MIT looked at data on how often people wash their hands and whether they do it properly, and simulated travel networks involving 2500 airports around the world to see what would happen.
They found at any one time, only 20 percent of people have clean hands.
Studies show 30 percent of people don't wash their hands at all after going to the loo, and of those who do, many either do it too quickly or don't bother using soap. And because we're not constantly washing our hands, eventually even clean hands get dirty.
Their calculations suggest if people at airports were encouraged to wash their hands properly and frequently up to a point where 60 percent of them had clean hands at any given moment, the worldwide spread of coronavirus could be reduced by 69 percent.
Vaccinlogist Helen Petousis-Harris of the University of Auckland said airports are "pretty good places for spreading".
"If you were to actually increase the hand sanitisation by a reasonable amount, you can actually limit the transmission by up to 70 percent, so it does make a difference," she told The AM Show on Thursday.
Some airports are busier than others. If the 60 percent clean-hands figure was achieved at just 10 key airports, transmission of the disease would be cut by 37 percent.
The most important airport to clean up is Heathrow, the study found, followed by LAX, Charles De Gaulle, Dubai, Frankfurt, Hong Kong, Beijing, San Francisco and Amsterdam. Some airports - like Narita International Airport in Tokyo and Honolulu International Airport don't serve as many passengers, but rank highly as transmission hubs because of their links to bigger airports and "they are located at geographically conjunctive points between the East and the West".
The best defence
COVID-19 is spread - the best of scientists' knowledge - through "respiratory secretions", says Dr Petousis-Harris - saliva and mucus, as well as in the eyes. If an infected person touches their face, there's a good chance they've transferred the virus onto their hands - which can then end up on surfaces or others' hands, and if they touch their face, the virus has potentially another victim.
Water and soap is the best defence. Health officials say it takes 20 seconds to ensure any potential diseases are eliminated.
"How many people do that?" asked Dr Petousis-Harris. "You push the tap and the water runs for six and you go 'oh, I'm done', and it turns off."
Alternative greeting suggestions to shaking hands have been suggested, such as tapping feet. Dr Petousis-Harris isn't sure it'll take off.
"We're gonna start falling over if we start doing that."
Instead, we should just wash our hands properly.
"It's a bit sad it takes something like a big epidemic like this to remind us we need to wash our hands a little bit more."
The researchers behind the airport study said even getting just a 10 percent improvement in hand hygiene at airports would dent the virus' spread by 24 percent.
"Eliciting an increase in hand-hygiene is a challenge," said Prof Christos Nicolaides, who co-authored the study, published in journal Risk Analysis.
"But new approaches in education, awareness, and social-media nudges have proven to be effective in hand-washing engagement."
