Today, in case you didn’t know, is Global Handwashing Day. An initiative launched by UNICEF and a number of other organisations, Global Handwashing Day has a simple goal: to promote handwashing with soap, and thereby prevent germ-transmitted diseases and infections from claiming millions of lives every year.

It is a great initiative, and highly necessary – but judging from history, it also faces very tough odds. We have known about the importance of handwashing since 1847, when the Hungarian physician Ignaz Semmelweis discovered it in a maternity clinic in Vienna. And yet, lack of handwashing remains one of the leading killers in today’s world, not just in developing countries, but also in fully developed ones.

The issue of handwashing illustrates one of the most intransigent problems of innovation: the Practicality Gap. By its very nature, innovation requires people to change their behavior, and this is exceedingly difficult to do. Worse, when the behavior we need to change is a well-established daily habit, it is nearly impossible. This is the Practicality Gap: if a new behavior cannot be effortlessly integrated into your working life, chances are that it won’t get done unless somebody literally forces you to do it.

What, if anything, is needed to bridge the Practicality Gap?

Information campaigns, while nice, are certainly not enough. We have long known about the so-called knowing-doing gap: being informed about the benefits of a particular behavior doesn’t necessarily make a difference, as witnessed by anyone trying to (take your pick): eat less french fries, smoke fewer cigarettes or visit the dentist regularly. We also need to make the desired behavior easy to indulge in; with handwashing, for instance, you need to make sure that people have access to soap and clean water when they need it.

But to make it worse, having the right tools at the right time is not enough either. A case in point is hospitals: doctors know better than anyone that handwashing saves lives, they have received training in how to do it, and in many hospitals, they have easy access to handwashing stations during their normal work. And yet, the lack of systematic handwashing continues to be a huge problem.

The issue is quite simply that handwashing is not practical to do as part of your normal working life. Handwashing, if it is to be done properly, is rather cumbersome and time-consuming. It brings no immediate experience of benefit, unlike the way you get an immediate experience of pleasure from eating something tasty. Nor does omitting it bring any immediate punishments – and the longer-term punishments, if they occur, often occur to somebody else (the patient) and not the doctor. In the busy everyday working life of a doctor, it is tempting to skip it.

Tellingly, some of the biggest progress in promoting handwashing has happened in British hospitals where the medical teams include a specialist job: a nurse who monitors the doctors directly and gives them hell if they don’t wash hands. This is fairly effective, but of course also rather expensive and is in many ways an inelegant solution. The world is still looking for a better and more elegant way to make it happen, but so far, it has proved rather elusive.