Отрицательное влияние ультрафиолетового излучения

The light from the Sun that reaches Earth consists of 50% infrared (>700 nm), 40% visible (400-700 nm), and 10% ultraviolet (200-400 nm).

 UV FEATURES 

Ultraviolet radiation comprises the most harmful radiation of the spectrum emitted by the sun. It is divided in three areas UVA, UVB and UVC.  The smaller the wavelength is , the more harmful UV radiation is. The smaller the wavelength of the UV radiation is, the less it goes into the skin and it only stays on the surface. 

UVA-UVB

From the ultraviolet radiation that reaches Earth 95% is UVA ,  5% is  UVB.UVC  is fully filtered by the atmosphere and doesn’t reach the surface of the earth. 

UVA area (320-400nm): It is constant and stable throughout the year. The radiation percentage of this area increases during summer months and reaches its peak during midday times.

UVΒ area (290-320nm): The biggest part of  UVB sun radiation is absorbed by the atmosphere. UVB radiation is toxic for the cells and causes DNA mutation.

Negative effects of  UV radiation

• Sunburn. 
• Damage to the skin collagen and elastin.
• Skin aging and wrinkles.
• Roughness, dryness, thread veins, unequal pigmentation.
• Immunosuppression damage in they eyes (cataract).
• Development of skin cancer and damage in the DNA (alterations ,precancerous or malignant).

Positive effects of UV when exposure is in moderation

• Vitamin D3 production (bones, immune system) 
• Psoriosis, vitiligo.

CONCLUSION  

It is necessary to use sunscreen products which protect from all the negative effects of  UV (not only from different types of skin cancer but also  photoaging, sunburn etc.