what are the active ingredients in sunscreen that make it work?
There are two major types of sunscreen: chemical and physical. Although the terms “sunscreen” and “sunblock” are often used interchangeably, chemical sunscreens absorb UV rays while physical sunscreens, or sunblocks, reflect them. Chemical sunscreens contain UVB or UVA absorbing ingredients and create a thin film on the skin that reduces ultraviolet radiation (UVR) penetration to the skin. These ingredients include chemicals like avobenzone and benzophenone, which absorb UVR [source: Environmental Protection Agency]. Chemical sunscreens often contain UVB-absorbing chemicals only; however, there are some chemical sunscreens that contain both UVB and UVA absorbers [source: American Melanoma Foundation]. Because they contain ingredients that physically block UVR, sunblocks provide broader protection against both UVA and UVB light [source: American Melanoma Foundation]. Physical sunblocks reflect UV radiation back into the atmosphere using ingredients such as titanium dioxide and zinc oxid
