Jane Powerson sunshine
As we Irish are only too aware, sunshine is one of the best antidepressants around - albeit scarcer than ever in the gloomy summer we've just had. It zings through our retinas and into the hypothalamus, boosting our mood, stimulating activity and appetite, and increasing our zest for life. Everything is better when the sun comes out to play.
Sunlight is not just a strong antidote to the blues, it's also a potent force against some serious pathogens. For thousands of years mankind has used the power of the sun for purification and disinfection. In 1877 a research paper by two Shropshire men, Thomas P Blunt and Arthur Downes, presented scientific evidence of its effectiveness. The paper, Researches on the Effect of Light upon Bacteria and other Organisms, proved that several hours of direct sunlight on test tubes killed off or inhibited bacteria within them, and rendered them bacteria-free for months. Blunt and Downes also showed that the wavelength with the most germicidal properties was the invisible one beyond violet: ultraviolet.
Their research was built on by legions of later scientists, who explored the uses of sunlight and UV in both high-tech and low-tech projects. It's the latter that interest this column most, because they're low impact (and, it must be said, because they're uncomplicated enough for its writer to understand).
One of the most appealing is Sodis - or solar water disinfection; see www.sodis.ch - a method for providing clean drinking water in areas where water sources are contaminated with pathogenic micro-organisms.
It couldn't be simpler: water is poured into clear plastic (PET) bottles, which are laid on their sides, and exposed to full sunlight for six hours (or, if it's a cloudy sky, two days). After that, the water is safe to drink. Regions between the latitudes of 35 degrees north and 35 degrees south are best suited for this treatment - in other words, places where clean water is often hard to find.
Although Sodis is not ideal for our more northerly island, let us not forget that it was its high-tech cousin, a UV disinfection system, that helped to lay the Galway beast of cryptosporidium to rest. And there are plenty of low-tech uses of sunlight that do work very well here - and which our mothers and grandmothers employed regularly.
They knew that sunlight was the best thing for bleaching and disinfecting bedlinen, tea towels, tablecloths and nappies. And that smells, moulds and other nasties could be banished from mattresses, bedding and rugs after a few hours in the open air on a fine day. They knew what we sometimes forget: that the simplest solutions are often the best and that, in the case of sunshine and oxygen, they are also free.