Ultravioettisäteily

Ultravioettisäteily (ultraviolet radiation) is a part of the electromagnetic spectrum with wavelengths between about 10 nanometre and 400 nanometre. It is divided into three main bands: UVA (320–400 nm), UVB (280–320 nm), and UVC (100–280 nm). UV rays are emitted by the Sun, fluorescent lamps and other artificial sources. The amount of UV reaching the Earth’s surface depends on factors such as solar angle, atmospheric composition, altitude, and cloud cover.

Exposure to UV radiation can have both beneficial and harmful effects. In small doses, UVB stimulates the production of vitamin D in human skin, which is essential for bone health and immune function. However, UV rays also damage DNA in cells, accelerate skin aging, cause sunburn, and increase the risk of skin cancers such as basal cell carcinoma, squamous cell carcinoma and melanoma. UVA contributes to photoaging and can also cause DNA damage. UVC is mostly absorbed by the Earth’s atmosphere and does not normally reach the surface, but laboratory studies show it is highly hazardous to skin and eyes.

In addition to biological impacts, UV radiation is used in industrial and medical applications. It sterilizes medical equipment and water by killing microorganisms, diagnoses skin lesions, and polishes organic polymers. Protective measures include wearing clothing with a high UV protective factor, applying broad‑spectrum sunscreens, seeking shade during peak sun intensity, and using sunglasses that block UVA and UVB. Monitoring devices called UV indices give public agencies and individuals an easy way to gauge present UV levels and plan exposure accordingly.