The light from the sun contains several kinds of ultra-violet (UV) radiation:
- UVA: Long wave radiation which has the strongest tanning effect but is also capable of burning the skin.
- UVB: Medium wave radiation which easily burns your skin and has a damaging effect on the elastin in your skin; it therefore causes the skin to wrinkle. It can be a cause of skin cancer.
- UVC: Short wave radiation which is the most dangerous kind of ultra-violet radiation to living cells. However, most UVC radiation is filtered by aqueous vapour in the ozone layer and atmosphere.
UVA and UVB radiation affects the skin in several ways. First, it makes the small vessels in the skin dilate which makes the skin redden. The sunlight also stimulates cells in the epidermis to produce pigment. In this way, the skin will gradually become tanned and tolerate more sunlight. However, the radiation also forms many free radicals upon reaching the skin and prolonged exposure to sunlight will cause the elasticity of the skin to be reduced. In the long term, this will result in wrinkles. People with delicate skin who are often sunburned could develop keratosis; a thickening of the most superficial horny layer of the skin. Finally, people who are eager sunbathers have an increased risk of developing skin cancer or malignant melanoma.
The sun provides its most damaging radiation in the summer period from April to October and the most intense hours of the day are between noon and 3 pm. You will also be exposed to UV radiation to some degree when it is cloudy, when you sit under an umbrella, or when you wear clothes that let some light pass through it. For this reason you can actually get tanned in the shadow - it only takes longer. However, if you stay behind glass, the heat radiation will penetrate the glass, but the tanning UV radiation will be kept back and you will avoid being burned.
Sunlight also dries out the skin.
Sunburns appear 2 - 6 hours after the skin having been affected by too much sunlight. The degree of the sunburn very much depends on how much pigment the skin contains - i.e. how tanned your are, your age, your skin's content of antioxidants, and which type of skin you have. Typically, blondes, redheads, and freckled people will be less tolerant of sunlight compared to others and they should therefore be extra careful. Some people cannot tolerate more than 15 minutes of strong sunlight - that is how delicate their skin is. When exposed to strong sunburn, the skin will form fluid-filled blisters. The skin will then require 3 - 6 months of healing before it is back to normal. The newly formed skin under the peeling is extra sensitive to sunlight.
Symptoms
The symptoms of sunburn is reddening of the skin with a feeling of soreness and warmth. A mild sunburn will have disappeared within 24 hours. A moderate sunburn which lasts for a couple of days will involve stronger symptoms; your skin will itch, be sore, and more swollen. In case of a severe sunburn, the skin can form blisters and accompanying fever with shivers and nausea might supervene.
Sunrash
A sunrash is a pruritic rash consisting of small, pale, pruritic spots and red stains. It can show up on the chest and arms - and sometimes the legs - anywhere from 1 hour to a couple of days after the skin having been exposed to sunlight. The worst cases can be seen in the spring when the skin has not become used to the sun. The rash is harmless and disappears after a couple of weeks. It is most common in girls and women between the ages of 5 and 40.
The shadow rule
In 2002, two Danish doctors presented a so-called shadow rule with the advantage of being very easy to administer. In short, it states that you should protect your skin from direct sunlight as long as your shadow is shorter than you, yourself.
Sunscreen
Two different types of UV filters or a combination of both can be used in sunscreen: chemical and physical ones. The active substances in the chemical filters penetrate the skin and provides protection whereas the physical filters reflect the UV light from the surface of the skin. There is no difference as to the effectiveness of the two types of sunscreen. However, research indicates that sunscreens do not offer sufficient protection against UVA radiation causing the skin to be exposed to damage from free radicals produced by the radiation.
In general, sunbathing is not unhealthy as long as you do not overdo it, are not deficient in antioxidants, and make sure to have a good balance between Omega 3- and -6 fatty acids in your diet. For most people, in order to meet these requirements, this means taking a daily fish oil supplement.
