Thursday, May 19, 2011

What should I look for in sunglasses?

What do I need to know about sunglasses?

The most important things to look for when choosing a pair of sunglasses is the amount of UV light that is blocked by the sunglasses and a proper fit. Lenses should be large enough to shield your eyes from most angles. It is important to note that darker lenses in sunglasses do not necessarily offer better UV protection. Sunglasses have many features, not all of which are related to the amount of sun protection they provide:
  • Blocks 99% of UV light:
    This is a very important thing to look for when purchasing sunglasses. This claim tells you that the sunglasses block 99 percent of harmful UV rays. The tag may also say "UV absorption up to 400 nm".
  • Wrap-around:
    This is another important thing to look for when purchasing sunglasses. These types of sunglasses wrap around the face and protect eyes from all angles.
  • Polycarbonate lenses:
    This type of lens is the most impact-resistant lens on the market today. (This type of lens does not necessarily offer better UV protection than other types of lenses.)
  • Blocks 90 percent of infrared rays:
    The amount of infrared rays sunglasses block does not effect the UV protectiveness of sunglasses. (Infrared rays are not harmful to eyes.)
  • Polarized:
    This type of lens does not help protect your eyes from damaging UV rays. However, this type of lens can improve eyesight by reducing distracting surface glare, most notably from water and snow.
In early 2000, the American Society for Testing and Materials (ASTM) has published new national standards for the preparation and labeling of fabrics and garments intended to protect humans from the sun's UVA and UVB radiation. The American Sun Protection Association (ASPA), a member of the ASTM standard drafting committee, is leading a national effort to encourage the sun protective clothing industry to adopt and promote the new standards in the U.S. marketplace.

The new ASTM standards D6544 and D6603 combine with AATCC 183 to form the most stringent UV-protective clothing standard in the world. "This is the credibility boost the U.S. sun protective clothing industry has been waiting for," said Mary Buller, ASPA Executive Director. "Finally, consumers will know what UPF is and will come to trust that the garment they buy will provide the same level of UV protection during its use-Iife as it did on the day it was purchased."

UPF Values Allowed
on Labels
Approximate % UV
Good UV Protection 15-24 15 and 20 93.3% - 95.8%
Very Good UV Protection 25-39 25, 30 and 35 96.0% - 97.4%
Excellent UV Protection 40-50+ 40, 45, 50 and 50+ 97.5% - 98.0%

D6544 requires fabrics making a claim of sun protectiveness to (a) undergo 40 simulated launderings, (b) be exposed to 100 fading units of simulated sunlight, and if intended for swimsuits, and (c) be exposed to chlorinated water prior to UV- transmission testing. The standards are currently voluntary, but could become mandatory if not adopted by the industry in a timely manner. Sun protection claims will be monitored by the FTC.