Dear Sherief

(Uv from the sun) They are many, but mainly: skin cancers, premature ageing, sunburn, free radicals generation, skin darkening and vitamin D synthesis

Dear Sherief,

UV-A is lower than UV-B in energy, but it penetrates our skin deeper to the superficial dermis (causes deep burns with UV-B), while UV-B do not reach the dermis but compensate for this by a greater harmfulness because of their higher energy (causes burns and skin cancer among others). UV-C are also very harmful, they are also the most dangerous, but they are absorbed by the ozone layer. The effect of these radiations is cumulative: the rate of mutation increases according to the dose of radiation received.

cordially

Good question. Among other things, UVB causes Thymine dimers to form within DNA strands. Two adjacent Thymine base pairs become chemically bonded due to ionization by UVB. This disrupts DNA replication, because the coding enzymes cannnot ”read” these dimers correctly. Hope this helps.

Of course, the cells which are exposed to UV become senescence. It already has been proved.

UV (ultraviolet radiation) is a dangerous from the sun or sunbeds can damage the genetic material (the DNA) in our skin cells. If enough DNA damage builds up over time, it can cause cells to start growing out of control, which can lead to skin cancer.

Today, the general guidelines are to a reduction of sun exposition. Some damages are listed in the previous answers....I am a meteorologist and I want underly that the UV Index is an internationally adopted Index to quantify the risk of human to sun exposition. The UV Index represente the maximum UV radiation level expected for a day. The UV risk exposure is important for all people; particular precautions have to be taken by outdoor workers, being exposed to the sun for several hours. World Health Organization (WHO) estabilish the rules for a correct sun exposition. In particular the precaution increases with the increasing of predicted UV Index. Only UV Indec lower than 2 can be considered safe (at least for the majority of population), for all other values it is suggested the use of shade, clothing, sunglasses, sunscreen... In addition it is always suggested to be exposed the less possible. I want remember you that solar UV radiation is however positively involved in the vitamin D synthesis (in some areas of the world where the solar UV radiation is low) were recorded some deficiencies in vitamin D.