It's almost summer and those long, wonderful days at the beach or out in the park soaking up the rays of the sun. Be sure, however, to wear your sunscreen to protect against those dangerous UVB rays.

We once thought that all we had to worry about was UVB, but the latest edition of the Harvard Women;'s Health Watch, (Sorry. This requires a subscription.) UVB is neither the only worry nor the worst worry when it comes to your skin:

Unfortunately, sunburn protection doesn't equal skin cancer prevention. UVB was once regarded as the main culprit in skin cancer as well as in sunburn, but experts now think that light waves in the ultraviolet A (UVA) part of the spectrum are no less important in contributing to skin cancer. UVA, which penetrates the skin more deeply than UVB, also contributes to skin aging.

The Ohio State University Fact Sheet has this to say on the topic:

Two types of ultraviolet rays (UV) from the sun exist: UVA and UVB. UVB cause burning of the skin or the red associated with sunburn, skin cancer, and premature aging of skin. UVA rays stimulate tanning but are also linked to other problems such as impaired vision, skin rashes, and allergic or other reactions to drugs.

Many sunscreens don't guard against UVA rays and there are no regulations, even for the ones that claim they do. The FDA's working on it. In the meantime, as ever, caution is the word.