Ultraviolet radiation is part of the electromagnetic (light) spectrum that reaches the earth from the sun. The wavelengths are shorter than visible light, which means that we can’t see them with the naked eye. These wavelengths are classified as UVA, UVB and UVC. Ultra Violet A is long wave and Ultra Violet B is shortwave. UVC radiation is the strongest, most dangerous form of UV light which is absorbed by the ozone layer and in theory doesn’t reach the earth, but as the ozone layer thins, more radiation reaches the earth. The ozone layer is in effect sunscreen for the earth, it blocks out damaging radiation. Both UVA and UVB penetrate the atmosphere, causing skin ageing, eye damage, including cataracts, and skin cancers. Exposure to ultraviolet radiation can suppress the immune system reducing our ability to fight off these problems.
It was once thought that only UVB rays would cause damage to the skin. UVB rays are responsible for skin burning which shows up as red, sore and blistered skin, which is an inflammatory reaction. More recent research shows that UVA rays cause long term damage to the skin, which isn’t immediately visible. The long wave UVA rays penetrate deeper into the subcutaneous layers below the dermis, causing damage to DNA and fibroblasts, as well as collagen degradation. UVA damages skin cells called keratinocytes in the basal layer of the epidermis where most skin cancers occur. The skin darkens when exposed to UV light in an attempt to prevent further DNA damage. During our lifetime we are exposed to large quantities of ultraviolet radiation causing cumulative damage.
UVA radiation penetrates deep into the skin and is responsible for premature ageing of the skin and skin cancer. Tanning beds can emit 2 to 5 times more UVA radiation than the sun.
UVB radiation is stronger than UVA radiation. It mainly affects the outer layers of the skin, causing sunburns, premature ageing of the skin, and skin cancer. These rays are strongest during the summer months – especially between 11 am and 4 pm.
Sunscreen should be used throughout the year with special attention given in Europe from April – October. Protect skin when traveling to high altitudes and when exposed to reflective surfaces, such as snow and water, which can bounce back 50% of the rays potentially damaging the skin twice.