Ultraviolet (UV) radiation is the part of the invisible radiation spectrum created by the sun. UV radiation is made up of elementary particles known as photons, which are categorised into wavelengths. The wavelength varies inversely in accordance to its energy – the shorter the wavelength, the greater its energy. The skin reflects some UV radiation naturally, but care must be taken since that which penetrates the skin tends to damage the cells permanently.
There are three types of UV rays: UVA, UVB and UVC. The UV radiation wavelength range is 100-400nm, often referred to as the Broad Spectrum. These levels are not constant and are subject to change from seasons, atmosphere and even the time of day.
UVA wavelength range: 320 – 400nm
UVA accounts for the largest amount of UV radiation to reach the Earth’s surface and accounts for 10% of all solar rays – 90% of UV energy received by unprotected skin comes from teh UVA range (Osterwalder et al).
Although lower in energy than UVB, it is believed that UVA causes damage to the connective tissue and increases the chances of skin cancer. 80% of UVA rays penetrate to the dermal layer of the skin and a further 20% penetrate even further.
UVA radiation can travel through clear glass and is mainly responsible for the ageing effect, causing wrinkling of the skin.