UV radiation (ultraviolet radiation) is part of the electromagnetic spectrum. It is next to the visible spectrum but is invisible to the eye. The main source of ultraviolet radiation is the sun. There are 3 types of UV radiation namely:
- UVA: Most UVA radiation gets to the earth. Overexposure to this type of UV radiation can cause cataracts and may contribute to the development of macular degeneration.
- UVB: Most UVB radiation is absorbed by the ozone layer and only a small portion of it gets earth surface. Exposure to a low dose of it stimulates the production of melanin (the pigment that protects the skin from the harmful effect of sun rays). However, exposure to high dose UVB radiation can cause sunburns which can result in skin cancers. UVB radiation is absorbed by the cornea and can cause ocular growths like pingueculum and pterygium.
- UVC: This type of UV radiation is completely absorbed by the ozone layer and so does not get to the earth.