Human skin can’t resist negative effects of sunlight by itself. The well-known kinds of ultra violet light are divided into three wavelength ranges: UVA (320-400 nm), UVB (280-320 nm) and UVC (100-280 nm)
As sunlight passes atmosphere, all UVC and 90% of UVB light is absorbed by ozone, water vapor and carbon dioxide. UVA light is less absorbed by atmosphere so that the light receiving to earth contains UVA and residual UVB lights.
UVA light causes disease like progeria or freckles through forming free radicals and disorder in skin refreshment process. UVB light has less diffusion and causes direct effects like inflammation, skin burn or in case of long time contact increases the possibility of different kinds of cancer.
Some people have more sensitive skin due to different factors. Skin irritability in these people is more common and inflammation or skin burn can perform faster on their skin. Generally, both chemical and physical absorbents are used to absorb UV lights.
Organic and natural reflective materials like Titanium dioxide are used in the formulation of this sunscreen. Also organic pigments are used in order to make a more natural layer on the surface of the skin.
Colored sunscreen suitable for dry and sensitive skins
Titanium dioxide Nano particles are used in this sunscreen. A parameter named “Solar protection factor (SPF)” is used in sunscreen data sheet which is used to determine the value of harmful lights absorbance.
The SPF value for sunscreen containing Titanium dioxide Nano and micro particles is presented in the following table. According to results the sunscreen containing Nano particles performs better in absorbance of harmful lights.
Sample | Micro particled sunscreen | Nano particled sunscreen |
Solar protection factor (SPF) | 7.31 | 60.33 |