uvstraling

UVstraling, or ultraviolet radiation, is electromagnetic radiation with wavelengths shorter than visible light and longer than X-rays. The spectrum is commonly divided into three bands: UV-A (315–400 nm), UV-B (280–315 nm), and UV-C (100–280 nm). Most UV-C is absorbed by the stratospheric ozone layer; UV-B is partially absorbed; UV-A reaches the surface with little attenuation.

Sunlight is the primary natural source of UV radiation. Artificial sources include tanning devices, mercury lamps, and certain industrial processes. The intensity of UV at the surface depends on latitude, season, time of day, cloud cover, and ozone concentration.

Health effects and protection: Short-term exposure to UV-B can cause sunburn and DNA damage in skin cells. UV-A contributes to skin aging and oxidative stress; long-term exposure increases the risk of skin cancers and eye damage, such as cataracts. UV exposure also promotes vitamin D production in the skin, which has health benefits in moderation. Protective measures include broad-spectrum sunscreen, protective clothing, sunglasses with UV protection, hats, and seeking shade during peak sun hours. The UV index is used to forecast outdoor exposure risk.

Applications and regulation: In medicine and industry, UV-C is used for disinfection and sterilization. Monitoring and public guidance rely on UV indices and related standards to manage exposure.

Environmental and historical context: Stratospheric ozone depletion raises surface UV-B, with potential impacts on ecosystems and human health. Ultraviolet light was discovered in 1801 by Johann Wilhelm Ritter.