And yet, it is still so hard to stop touching our faces. Much of the time it is spontaneous, and we are not even aware of it. One study caught medical students in class touching their faces 23 times per hour on average. “It’s human nature to want to touch your face,” says Dr Otto Yang, an infectious diseases expert at University of California, Los Angeles (UCLA).

There’s a reason for that. Touching our faces may be related to negative feelings – a feeling when we have failed to achieve a goal or are not satisfied, according to a research article published in the journal PLoS One.

Face touching can help us deal with anxiety and discomfort, and may be comforting, the report says. We might think we want to touch our faces because of a perceived itch or to groom ourselves, but research suggests we are actually doing it because we are somehow uneasy or unsettled, according to the research.

Touching our faces is also thought to be a way we might try to avoid being distracted. In a study of face touching, researchers concocted ways of trying to distract study participants during a difficult mental task, and found that the human test subjects increasingly touched their faces when their attention was distracted and they needed to refocus.

Unfortunately, the things we touch the most often can often be filthy, such as our smartphones – which we probably touch as soon as we wash our hands.

Colonies of bacteria were discovered on the vast majority of health care workers’ cellphones in one study; 93 per cent of the phones studied were found to be crawling with germs. Most non-health care workers’ phones were also dirty, with 58 per cent of them home to microbes, according to the study, published in the Iranian Journal of Microbiology.

“Mobile phones are not only capable of transferring messages but also are disease-producing microbes,” the study found.

While many people fear being sneezed or coughed on, there is plenty of convincing evidence that shows just how easy it is for a virus to enter through face touching.

Some viruses can survive for days on hard surfaces, just waiting to be picked up by a new fingertip. One study in the Journal of Hospital Infection found flu virus persisting on hard surfaces in flu patients’ hospital rooms. The virus was found on a computer mouse, bed rail, wall, sofa and clothes.

Sometimes, it may not be the droplets in the sneezes and coughs that are most infectious. Instead, the virus is in the snot, and the infected mucus is probably what helps it spread from person to person, and hand to hand, according to a number of studies.

And those seeking safety in masks should realise that they do not keep you from touching your face. Surgical masks do not cover the eyes. And people wearing masks can sometimes get an itch on their nose, and if they rub their nose through their mask, they are likely to rub their eyes, says Dr James Cherry, a UCLA infectious diseases expert.

“Viruses are very happy infecting through the eyes as well as through nose and mouth,” Cherry says.

So what can people do to break the habit? It is not going to be easy, and some of these ideas will probably sound weird. Nonetheless, people have kicked other habits commonly now seen as gross.

Start being mindful when you do touch your face, catching yourself when – and, preferably, before – you do it. If you catch yourself before touching your face, consider folding your hands or doing something else with them, suggests one skin beauty care website.

Got an itch? Try to ignore it. If that’s bothersome, wash your hands, then scratch it, then wash your hands again. Or buy sterile wooden tongue depressors to use as a tool to scratch itches.

Perhaps consider wearing gloves. The latest food safety gloves can also be used on smartphone screens, and gloves might make you more conscious about touching your face.

Do not get discouraged if it seems hard to learn how to not touch your face.

“Politicians, for example, learn through extensive training to restrain from touching their face during public speaking,” says Martin Grunwald, author of a book on face touching, and an expert on the subject at the University of Leipzig in Germany. He also co-wrote the study published in PLoS One on face touching. Still, he notes, “this behaviour requires extreme self-control and is extremely trying”.