There are people in many countries of the world who are exposed to hours of sunshine each and every day because of where they live or because of the work they do (and the two are not mutually exclusive).
For example, there are many places where the sun is up from dawn until dusk for most of the year and yet the people are still expected to work in the fields each and every day.
Similarly, there are many popular holiday destinations where it is common to see local children playing football and other games on the beach from breakfast until dinnertime with the sun blazing down, and yet they never seem to suffer any significant burns or other skin damage from the sun.
Although it is impossible to generalize as to why this is the case, there are a couple of reasons to put forward to explain it.
Firstly, if you live in a place where the sun is an almost permanent daily feature in your life, it would be very difficult not to get used to it over time.
If you are exposed to regular long ‘sessions’ in the sun from a very early age and generation after generation of your ancestors have been in exactly the same situation, it seems reasonable to suggest that there has been a degree of ‘learned resistance’ to the worst effects of the sun over a long period of time.
Secondly, as previously suggested, it is a fact that fair skinned people, those who have light or red hair and/or blue or green eyed individuals are more likely to suffer physical harm as a result of overexposure to the sun.
To a large extent, this makes a great deal of sense because these physical characteristics are those that are most commonly attributed to individuals who are from or have roots in colder countries where the sun is not such a major factor.
The influence of geography is further emphasized by the fact that there are locations in the world where for long periods every day during the winter, there is no daylight, never mind sunshine. And even when the sun does come out, it does so with less intensity and people are therefore less well adjusted to the effects of the sun.
The intensity of sunlight also increases as you climb to higher altitudes although this does not necessarily mean that the temperature does the same. On the contrary, as anyone who has ever been in an airplane at 30,000 feet will be very well aware, the temperature as you climb higher falls dramatically, which is why even in the midst of summer, the highest mountains in the world will always be covered with snow nearer the summit.
The combination of snow and intense ultraviolet radiation at altitude is one of the reasons why mountaineers can suffer extreme sunburn when they are climbing. In this scenario, the climber has two problems.
Firstly, they are in a situation where the ultraviolet light coming directly from the sun is far more intense because they are closer to it and as a result of a far thinner layer of air above them.
Under normal sea level conditions, the dense layer of air above us filters many of the most harmful of the sun’s rays, whereas dirt and pollutants deflect or reflect more of those rays, ensuring that they never reach us. However, at altitude, the protective layer provided by the air is far thinner and as a consequence, far higher levels of potentially harmful UVA and UVB radiation gets through.
At the same time, the snow provides a perfect mirror for this radiation to bounce off which further intensifies the level of radiation, heat and light. This is one of the reasons why mountaineers and people who live at high altitudes are especially prone to sunburn.
Geography, ambient climactic conditions and other physical factors such as altitude all combine together to make some people more susceptible to skin damage caused by the sun, whereas there are other people who through a trick of fate are far more likely to suffer skin damage because of overexposure to ultraviolet light.
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