photo source: www.geneplanet.com
Sunscreens are for topical preparations containing substances that partially or completely block light radiation. They appeared in the 1940s for photoprotection of American soldiers in the Pacific during World War II, since then its use has spread universally.
They are classified into two groups: partial or total chemical and or physical. The degree of protection from attempts to quantify a filter through so-called sun protection factor (SPF), or simply more protection index (PI). It is expressed with a numeric index ranging from 4 to maximum of 35 or more. (more…)
After the filtered air and the environment, light reaching us is composed of UVB, UVA, visible light and infrared 