The Different Types Of UV Radiation

There are different types of UV Radiation and they affect the skin in different ways.

 UV-A radiation has the longest wavelength. The earth receives UV-A rays all year, round and it is not filtered at all by the ozone layer. It is responsible for aging, and can penetrate the skin right down beneath the four layers of the epidermis to the dermis.  It also is the type of rays that tanning lamps emit and can cause sunburns. UV-B is another type of radiation that is filtered by the ozone layer, and will penetrate the skin to the bottom of the epidermis. This is where the basal cells are produced, and is responsible for breaking the molecular bonds thereby altering the structure of the cells by dividing them.  

UVB is present during the summer between 10 am to 4 pm, and is higher closer to the equator.  It is the cause for most DNA damage and is the cause of most sunburn. A sunburn is erythema, a dilation of capillaries, with the result of reddened skin.  At high altitudes, where the air is cleaner and thinner, there is more UV-B radiation. 

UV-C has the shortest wavelength and is usually filtered by the ozone. It has the most intensity, and is used to kill bacteria and sterilize hospital equipment. When it hits the ozone, up to 85% is reflected from surfaces, and is thrown off in all directions.