Answer to Question #1206 Submitted to "Ask the Experts"

Q

What material will sufficiently block ultraviolet-A (UVA) and ultraviolet-B (UVB) radiation while outside? What "film" is used to coat sunglasses to deem the UVA and UVB safe?

A

The answer to the coating question is a trade secret and is generally not available from the manufacturers of sunglasses. While outdoors one needs to know that different fabrics have different protection levels, the tighter the weave the greater the protection level. In addition, dark colors of the same material tend to absorb/block more ultraviolet (UV) radiation than light colors. Many fabrics tend to have a lower protection factor when wet. UV absorbers can be added to materials by clothing manufactures to enhance UV protection, but now we are back to the trade secret answer. Another avenue to go down would be to ask the manufacturers for a Material Safety Data Sheet (supplied by the chemical or product manufacturer and lists chemical physical properties and health and safety information) which would give information about the coatings. Ken Barat Laser Safety Officer/Nonionizing Radiation Officer Lawrence Berkeley National Laboratory