What does UV radiation mean?

What are UVB rays and what are their effects?

UVB rays are for the most part absorbed by the ozone layer and have a wave length of 280 - 320 nm. They do not penetrate as deep in the skin as the UVA rays. Due to a higher absorbing energy in the upper skin layer, the UVB rays are responsible for solar erythema (sunburn). The erythemal reaction normally follows three to six hours after sun exposure.

UVB rays have following effects:·

• slow but long lasting tan due to the increased production of melanin and provocation of the so called light induced callosity
• develop sunburn, with higher burning risk on the zones with thin skin (areas without hair, nose, shoulders etc.)
• through its high energy, the UVB rays can directly damage the DNA in the skin cells and in this way overstress the skin’s own repair mechanism.

What are UVA rays and what are their effects?

The UVA rays are long wave UV-rays (320 - 400 nm) with lower energy, but very high potential to penetrate deep into the skin. Approximately 90 - 95 % of the UV radiation reaching the surface of the earth are UVA rays. UVA cause an immediate pigmentation of the skin but does not enhance the production of melanin.


UVA rays have following effects:

• direct and fast tanning of the skin, not very long lasting (same sun-beds)
• the pigmentation by UVA does not increase the protection of the skin
• premature aging due to the deeper penetration into the skin. Damaging of the collagen and elastine structure with cumulative effect
• damage through the development of free radicals over a period of time the DNA directly, but without any repair possibility
• responsible for more than 80% of sun allergies