If you think your sunscreen is protecting you from skin cancer, you may well be correct. On the other hand, you may have to investigate your products of choice in order to be sure. Not all sunscreens are the same.
Research shows that while most brands of sunscreen do protect you from short-wave ultraviolet radiation, many do nothing at all to protect you from dangerous long-wave radiation. Not good news really.
So how can you tell if your brand provides the protection you need? Fortunately that's pretty simple. Just look on the label to make sure it contains the ingredient that has been proven to block long-wave UV rays (see below).
Let's consider the ABC's of the suns rays, that is, the different types of ultraviolet radiation to which we are exposed.
UVA: This is long-wave radiation between 320 and 400 nanometres. It is responsible for most photosensitivity reactions, and also contributes to chronic skin damage and sunburn. It penetrates deeper into our skin than UVB radiation. Its level is relatively constant during daylight hours.
UVB: The midrange of ultraviolet radiation (290 to 320 nm) is the major cause of sunburn and chronic skin injury, including aging and skin cancer. It is most intense between 11 am and 4 pm. It is able to penetrate through 1 metre of water, and is reflected 17% by water, 50% by sand, and up to 80% by snow.
UVC: This wavelength of radiation does not reach the earth's surface, as it is blocked by the ozone layer. However it is found in artificial light sources such as tanning beds. It may cause erythema, or sunburn.
Sunscreens work by "absorbing" the sun's rays so that they do not hit the skin. Their relative effectiveness is measured by the Sun Protection Factor (SPF). The higher the SPF, the more, or longer the protection you receive.
The various components of your sunscreen may include agents that protect against UVB radiation such as cinnamates, salicylates, and para-aminobenzoic acid (PABA) and its esters. Parsol should be a component of any sunscreen, as it is the only chemical which blocks UVA, the long-wave radiation.
True sunblocks include titanium dioxide and zinc oxide. They are particularly useful on the more exposed body parts, such as ears and noses.
People in the southern hemisphere are heading off to the beach in large numbers while northern hemisphere dwellers are heading into the snow. Both are in need of good quality sun protection. Take care out there.