International Scientific Manager, La Roche-Posay Pharmaceutical Laboratories, Asnières, France
- Page(s) : 164
- Published in: 2001
There is increasing awareness that exposure of skin to UVA radiation cannot be considered to be without risk.
The amount of UVA reaching the surface of the earth is approximately 20 times greater than that of UVB. Moreover, unlike UVB rays, UVA rays are not attenuated by the ozone layer, they pass through clouds and glass and are emitted at a constant rate throughout the day from the sunrise to the sunset. Finally while 90% of UVB radiation is blocked by the stratum corneum, over 50% of UVA radiation is capable of penetrating deep into the cutaneous structures as far as the papillary and reticular dermis.