What is tan?
In ancient times people believed, that the sun is divine, and its impact on people is beneficial. For example, Hippocrates believed that sunbathing helps from rickets, and the Chinese believed that the sun - it's the drug of smallpox.
Now we perceive the sun as a source of radiation. Some types of radiation we do not see or feel, others take as heat and light. Only three types of UV radiation reach the Earth's surface. This are: a long-wave rays of type A, short-rays of type B and gamma rays of type C.
The most dangerous for the human body is gamma radiation, but it almost does not reach the Earth's surface, being scattered in the ozone layer of the atmosphere. Following gamma-radiation goes long-wave rays. This rays constitute only 3.5% from the entire solar flux. These rays penetrate our skin and affect the aging processes, unfortunately, accelerating them. But under the influence of short-wave rays, cells of the skin produce melanin.
Melanin - is the pigment produced by special skin cells (melanocytes), under the influence of sunlight. Intensity of the tan shade, exactly depends on the melanin and its quantity in the skin. Production of melanin - is a protective reaction of the body to a sunburn. The sun's rays in the big doses can cause cancer diseases and burns on the skin - erythemas, and in moderate amounts they are useful, contributing to the production of melanin. It is important to remember that melanin should not stand out more than be oxidized, and thus you can avoid unpleasant consequences, and get only pleasure from the sunbathing.
Just recently pale skin was considered the standard of beauty and wealth, but the changes have come into our world and everything changed. Now tan - is a symbol of prosperity. The workers spend all days long in the offices, and people with a prosperity, are carefree and have plenty of time to lie down in the sun.
Tan became fashionable in the second half of the 20th century with the submission of Coco Chanel, but the effect of tan on human health was found earlier, in the 1900s. Then people invented heliotherapy - a method of treatment with sun. Later was invented solarium. Despite the fact that at that time "artificial sun" was expensive pleasure, it was very popular.
The sun's rays in the right quantity has therapeutic properties in such diseases as: psoriasis, acne, eczema, atopic dermatitis, and others. Sun has also a positive effect on the production of vitamin D in the body, which is responsible for the absorption of calcium and phosphorus, positively affects the blood circulation, accelerates the healing process and increases the tone.
But there are contraindications to stay on the sun. Before planing a vacation in the warm countries where the sun is more active than usually, its desirable for people with such problems to consult a doctor. The reasons for limiting stay on the sun: taking medicines that increase the light sensitivity; the presence of numerous pigmented spots and birthmarks; hypertonia; tuberculosis; cardiac and liver dysfunction. In the presence of dermatitis, it is desirable to avoid direct sunlight, because already dry skin dries out even more, this will only worsening the disease.
The positive sides of tanning in solarium are the exclusion of the impact of gamma rays and the possibility of regulation of the dosage and the intensity of sun rays at influence on the human body. If you will correctly calculate the dosage, then tanning session will be completely safe.
A tan acquired in the sun, almost does not differ from tanning in solarium. Shade and duration of the result will be the same.