Ultraviolet light is a type of electromagnetic radiation, as are radio waves, infrared radiation, X-rays and gamma-rays. UV light, which comes from the sun, is invisible to the human eye. It makes black-light posters glow, and is responsible for in our case summer tans but also sunburns too.
UV light can be categories like this:
- UVC (200-280nm) – is considered to be potentially more capable of burning the skin and is almost completely absorbed by the atmospheric ozone layer.
- UVB (280-320nm) – most efficient wavelength for stimulation of melanin (pigment) production; overexposure causes erythema (sunburn); produced in small amounts in low pressure tanning equipment.
- UVA (320~00nm) – most efficient wavelength for pigment oxidation; can penetrate deeply into the skin to potentially damage underlying tissue; its longer wavelength reduces UVA’s ability to cause erythema (sunburn) by a factor of up to 1000; UVA is produced by all indoor tanning equipment and is considered to be the primary cause of premature aging of the skin (photoaging).UVB and UVA rays can affect the skin in a positive or negative way, depending on the dosage and scheduling of exposure.