Getting out in the sunshine is one of the great pleasures of life. Like most things, sun exposure is good for us in moderation but can cause problems if we overdo it. So what are the facts, and how much sun is too much?
Fashions in sun exposure vary greatly around the world, and have also changed over the years. Many Europeans now want to be tanned, while Asians prize white skin. A suntan used to be the mark of the lower classes, until the advent of the ‘jet set’ in the 1950s changed it to be the badge of wealth and leisure. Now many Westerners are obsessed with getting their skin to darken, and warnings about the risks fall on deaf ears.
We all know about sunlight, but the relevant rays for our health are those that we can’t see – the ultraviolet (UV) rays. Two types penetrate the atmosphere, and are known as UVA and UVB. Both cause changes in the human body, both good and bad.
As well as lifting our mood, sunlight is essential for good health. The body uses sunlight to make vitamin D, which is also available from food. Vitamin D is essential for strong bones – deficiency causes the disease known as rickets in children, and contributes to osteoporosis in adults. Because reaction to sunlight varies so much between people, it is not possible to set a definite amount of time outside that will ensure sufficient vitamin D production. However most people who don’t spend the whole day shut in the house will get enough sunlight from a few minutes outside.
Winter UV levels in the UK are too weak to allow the body to make vitamin D. Most people will have enough stored in their bodies, as long as they have spent a reasonable time outside in the summer and eaten a healthy balanced diet. As usual, there is no need for healthy people to take dietary supplements.
So sunshine is good for us – in moderation. Problems begin when people expose themselves to excessive UV in the pursuit of a ‘healthy’ tan. There is of course no such thing - a tan is the sign that the skin is being damaged, and is reacting to protect itself. Widespread ignorance about UV strength and the effect on health leads to skin cancer and premature skin aging, as well as to the reddened and peeling skin that is seen all too often after a sunny weekend.
Some of the persistent myths must make teachers wonder if people paid any attention at all at school. ‘It’s not that hot even though it is June, I don’t need sun-cream.’ ‘A sunburn will turn into a tan as long as it doesn’t peel’. ‘If I wear sun-cream I will just stay white’. None of these are true.
The strength of the UV rays that we receive from the sun has absolutely nothing to do with the temperature of the air on the day. People do get more sunburnt on hot days, but that is because they are outside longer and wearing fewer clothes. Anyone who needs proof that temperature is not related to UV strength need only see what happens to skiers who go up mountains, in snow, and forget their sun-cream.
So what does control the strength of the UV rays? These are the main factors:
· Time of year; in the northern hemisphere, the sun’s rays are strongest around the summer solstice on June 21st.
· Time of day: a good rule is ‘short shadow? Seek shade!’ If your shadow is shorter than you are, which is usually between 11am and 3pm, it is time to find shade.
· Latitude and altitude: as you move nearer the equator, the sun will pass more directly overhead and there will be less atmosphere above you to filter the UV. If you move up a mountain, there will also be less atmosphere to protect you.
· Cloud cover: clouds do filter the UV, but not as much as most people think. It is perfectly possible to get sunburnt on a cloudy day in the UK.
Even if you are in the UK, if you are going to be outside for more than a few minutes you should use sun-cream. The best all-purpose choice is factor 30 cream or lotion, which means that you will be protected against UVB for 30 times longer than the time it would take your unprotected skin to burn. Also look for the star rating on the bottle, which shows levels of protection against UVA. Some rays will still pass through the cream, but levels will be much lower. Suncreams do rub off and wash off, so need to be reapplied regularly. Note that levels of sunscreen in moisturisers are generally too low to be effective.
If you are moving south on holiday, then the suncream needs to be applied more frequently, and possibly in a higher factor. Think twice before deliberate sunbathing – you will get all the sun you need and more simply by being outside in that lovely weather. Seek shade in the middle of the day, cover up if you are in direct sun for long periods, and take particular care to ensure that children are protected.
Everybody should make the most of sunny days – but treat those rays with respect. Aside from the skin cancer risk, consider what you are doing to your skin. Enjoy the sun – but remember that tanning is the process used to make leather.