Defining Ultraviolet (UV) Radiation
Ultraviolet (UV) radiation is a form of electromagnetic radiation with wavelengths shorter than visible light but longer than X-rays. It is invisible to the human eye and carries more energy than visible light, making it capable of causing chemical reactions and cellular damage. The UV spectrum typically ranges from 10 nanometers (nm) to 400 nm.
Types of UV Radiation: UVA, UVB, and UVC
UV radiation is categorized into three main types based on wavelength: UVA, UVB, and UVC. UVA (315-400 nm) has the longest wavelength and penetrates deepest into the skin. UVB (280-315 nm) has a medium wavelength and causes most sunburns. UVC (100-280 nm) has the shortest wavelength and highest energy, but it is almost entirely absorbed by Earth's atmosphere, primarily the ozone layer, and does not reach the ground.
Common Sources and Exposure
The most common natural source of UV radiation is the sun, with both UVA and UVB rays reaching the Earth's surface. Artificial sources include tanning beds, which primarily emit UVA, and specialized UV lamps used for sterilization, water purification, and industrial curing processes. Welders and germicidal lamps also produce significant UV radiation.
Impact and Applications of UV Radiation
UV radiation has both beneficial and harmful effects. Beneficial aspects include stimulating Vitamin D production in skin, which is crucial for bone health. Harmful effects range from sunburn and premature skin aging to DNA damage, which can lead to skin cancer, and cataracts. Industrially, UV light is used for disinfection, curing resins and inks, forensic analysis, and scientific research due to its ability to break chemical bonds and excite electrons.