Sun and UV rays
The sun provides many positive effects for each of us. The general well-being is increased, immune defences are strengthened, blood pressure and cholesterol levels are lowered and blood circulation and metabolism are stimulated. The body needs a minimum amount of sunlight in order to produce vitamin D, which the body needs for an intact calcium balance.
However, excessive sun exposure can have negative effects on the body. Acute sun damages can occur immediately, after hours or days. Sunburn, sun allergies (light dermatosis), other phototoxic reactions, but also sunstroke and head stroke can occur. Fortunately, for some time now people have also become more and more aware of chronic sun damages. The danger to suffer from black or white skin cancer, but also the accelerated skin aging or the formation of pigment spots caused by excessive exposure to the sun, is meanwhile know by broad public.
Repeated sunburns in childhood are the main reason for chronic sun damages!
Sun rays are electromagnetic waves with different wavelengths. From the solar spectrum shown above, only UVA and UVB rays, visible light and infrared rays reach the earth’s surface. Even if UV rays only make up 4.3% of the total solar spectrum, they have a great impact on the skin. UV rays differ regarding:
- Their biological effects on the skin
- The depth to which they penetrate the skin
- Their energy
UVA rays penetrate into the dermis with the connective tissue and blood vessels. There they act on the tear-resistant collagen fibres and elastic fibres. The latter are responsible for the suppleness and adaptability of the skin. If excessive exposure to UV-A radiation occurs, the resilience of the elastic fibres is impaired and the connective tissue weakened. The consequence: The skin ages faster, becomes limp and wrinkled.
It is also proven that UVA rays are responsible for the formation of free radicals, which increase the risk of certain types of skin cancer.
Additionally, UV radiation is responsible for the development of pigment disorders, the increase in light sensitivity after taking certain drugs, as well as polymorphic light dermatosis, commonly known as “sun allergy” or “Mallorca acne”.