There are about 3 million non-melanoma skin cancers, and 150,000 melanomas diagnosed each year around the world. There is overwhelming evidence that UV radiation is a major cause of precancers, skin cancers, and skin aging.
UV radiation consists of UVA, UVB and UVC. UVC does not penetrate the atmosphere, and thus doesn’t impact us.
What Is the Difference between UVA and UVB?
UVA penetrates the skin more deeply than UVB and is the dominant tanning radiation. Tanning, whether outdoors or in a salon, causes cumulative damage. Most of us are exposed to large amounts of UVA throughout our life, as UVA rays account for up to 95 percent of the ultraviolet radiation reaching Earth’s surface. UVA is less intense than UVB, but it is present with about equal intensity during all daylight hours throughout the year. UVA does penetrate clouds and glass.
UVB is the primary cause of skin reddening and sunburn. Because it tends to damage the skin’s more superficial epidermal layers, UVB plays a key role in the development of skin cancer and a contributory role in tanning and photo-aging. Its intensity varies by season, location, and time of day. The most significant amount of UVB hits the U.S. between 10 AM and 4 PM from April to October. However, UVB rays can burn and damage your skin year-round, especially at high altitudes and on reflective surfaces such as snow or ice. UVB rays do not significantly penetrate glass.
Studies consistently have shown significantly more pre-cancers, non-melanoma skin cancers and even melanomas on the left side of the face. Why is this? We are exposed to significant amounts of UVA rays when driving. While the amount of exposure might seem insignificant it really adds up over the years. Another theory is that the way people sunbathe may be involved. One researcher in Britain (where people drive on the right side of the car) suggested “If people sunbathing in the northern hemisphere tend to lie facing south in the morning, the left side of their body might be exposed and sunburned as the sun moves from east to west, making them more likely to cover up by afternoon,” they say.
We recommend daily application of a good quality sunscreen, protecting from both UVB and UVA. For information choosing a sunscreen see http://www.skin-vein.com/blog/how-to-choose-the-right-sunscreen and http://www.skin-vein.com/blog/sunscreen-101.