Skincare is concerned with three categories of light rays ultra-violet (UV), visible and infra-red rays. The three types of UV radiation are classified according to their wavelength including UVA, UVB and UVC. They differ in their biological activity and the extent to which they can penetrate the skin. UVA and UVB rays are well known to cause damage to our skin. UV rays are more harmful in certain locations and at certain times of the year, most intense during the summer and nearer the equator.
Understanding of exactly what kinds of damage each causes to the skin, a can help you pick out the best sunscreen for you and give you insight into just what each ray is responsible for.
What is Ultraviolet Radiation?
Ultraviolet or UV radiation is part of the electromagnetic (light) spectrum that reaches the earth from the sun. It has wavelengths shorter than visible light, making it invisible to the naked eye. These wavelengths are classified as UVA, UVB, or UVC. With even shorter rays, most UVC is absorbed by the ozone layer and does not reach the earth. Both UVA and UVB, however, penetrate the atmosphere and play an important role in conditions such as premature skin aging. By damaging the skin’s cellular DNA, excessive UV radiation produces genetic mutations that can lead to skin cancer.
UVA wavelength is the longest of the three at 320–400 nanometers (nm). UVA rays account for up to 95% of the UV radiation reaching the Earth’s surface. They pass through the ozone layer and reach the earth. They are present with relatively equal intensity during all daylight hours throughout the year. UVA rays are so powerful that they also penetrate some clothing, clouds and even glass. Also UVA rays contribute to skin ageing and wrinkling because they are able to penetrate deepest into the skin, damaging the cells beneath.
UVA is the dominant tanning ray, and we now know that tanning. A tan results from injury to the skin’s DNA; the skin darkens in an imperfect attempt to prevent further DNA damage. UVA may serve to initiate the most dangerous form of skin cancer. These include melanoma. According to recent research, first exposure to tanning beds before the age of 30 increases risk of skin cancer by 75%.Recently, studies have identified that this form of radiation affects the body’s immune system and acts as an immunosuppressive agent. Research has also shown that exposure to UVA actually causes a large fall in the body’s immune cells which in turn make it easier for malignant cells to grow.
UVB wavelength is 290-320 nm. UVB rays are intensity varies by season, location, and time of day. They are strongest in northern hemisphere summer months or when parts of the earth orbit closest to the sun. UVB rays, the chief cause of skin reddening and sunburn, tends to damage the skin’s more superficial epidermal layers. They can also lead to the development of skin cancers. It plays a contributory role in tanning and photoaging.
Unlike UVA rays, these rays aren’t always the same strength year round – They’re more prevalent in the summer months, however they are able to reflect off of water or snow, so it’s always important to protect yourself year-round. UVB rays are responsible for causing most skin cancers. While large doses of UVA rays can contribute to cancer, it’s the UVB rays that are commonly to blame.
UVC wavelength is 200-290 nm that have the shortest wavelength. They are the most dangerous among all the rays. However, these rays do not reach the earth’s surface as they are completely absorbed by the ozone layer.
UV rays present react with melanin. Melanin is an active defense against the sun, since melanin absorbs UV rays before they can hamper your skin. Melanin causes color of the skin. When melanin increases in response to sun exposure, the skin begins to tan.
As above, UV rays are part of how the energy from the sun reaches the earth (UVA, UVB). Risk factors associated with the development of skin cancer. Protect your skin by sunblocks or sunscreens which protect against UVA and UVB rays or “broad spectrum coverage” and you should avoid being in the sun between 10 am and 4 pm since that is the time when the sun is at peak.