There is a deep-rooted idea in the Western world that fresh air and sunshine are good for us. Going back to medieval times, the spread of disease was often blamed on bad or malodorous air.

The idea that fresh air could cure has been current right up until our recent history. During the 19th century even medical and health professionals such as Florence Nightingale encouraged patients to take fresh air. Fresh air and sunshine were regarded as the cure for all that ails.

We may be tempted to look back on these notions, armed with our ‘thoroughly modern medical ideas‘ and smile knowingly at the quaintness of such a concept. For while we understand that sunshine is essential for manufacture of vitamin D within our bodies, the idea that sunshine and fresh air are part of a hospital treatment seems, frankly, backward.

Well, it looks as though all those medics of yesteryear may have been on to something after all…


In the case of sunshine, we now know that ultraviolet light is rather effective at killing bacteria. In particular, ultraviolet light at the specific wavelength of 207 nanometres is fully absorbed by teeny bacteria, but causes minimal damage to much larger human cells . All that absorbed ultraviolet energy causes damage to bacterial DNA and kills them stone dead.

Fresh Air

More intriguing is the effect of fresh air in hospitals.

It’s not really surprising that hospitals are full of nasty bacteria which are, of course, full of poorly patients, many of whom are harbouring pathogenic bacteria.

What is more surprising is that if you open a window, many of these nasty bacteria are not present. it is only recently that we have begun to appreciate how rich and diverse and ubiquitous the bacterial ecosystem that surrounds us really is. Unfiltered, un-air-conditioned, fresh air is full of a huge variety of bacteria floating about on dust and in tiny water droplets. If a surface is exposed to this air, then these bacteria will settle and where suitable resources are available they will grow and flourish. Most of the bacteria are harmless. Those few bacteria that potentially cause disease or infection have to compete with a whole range of other bacteria; consequently, they cannot predominate and are less of a risk to us. If you open a window in a hospital room, whose surfaces are regularly disinfected, those surfaces will be recolonized by a vibrant ecosystem of bacteria containing far fewer of the nasty variety. This seems to imply that we should stop cleaning hospital rooms and just open the window, but it is not that simple. Regularly cleaned hospital rooms still have fewer bacteria overall, which is a good thing when vulnerable people are using the room . But if the windows are opened between the cleaning, the bacteria that are present will be less likely to cause a disease or an infection.

Florence Nightingale became a household name after her brilliant nursing work during the Crimean War. One of her most significant innovations was the rigorous application of cleanliness within her hospital wards, including a constant supply of fresh air. On her return to the United Kingdom she carried on her pioneering work, and is largely credited with the founding of the modern nursing profession. While many of her principles have remained in current practice, her ideas on fresh air have fallen out of vogue. Perhaps it is time to revisit this idea. As she put it, over a hundred years ago in 1898:

‘Never be afraid to open windows.’