What Is UV

What is Ultraviolet (UV) Light

Ultraviolet Light

Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV. It is named because the spectrum consists of electromagnetic waves with frequencies higher than those that humans identify as the color violet.

Although ultraviolet radiation is invisible to the human eye, most people are aware of the effects of UV through sunburn,and in tanning beds. The UV spectrum has many other effects, including a germicidal effect on micro-organisms preventing their build up.

UV light is found in sunlight and is emitted by electric arcs and specialized lights such as black lights. It can cause chemical reactions, and causes many substances to glow or fluoresce. Most ultraviolet light is classified as non-ionizing radiation. The higher energies of the ultraviolet spectrum from about 150 nm (‘vacuum’ ultraviolet) are ionizing, but this type of ultraviolet is not very penetrating and is blocked by air.

UVC Diagram

UV-A (Ultraviolet A, UVA, long wave, or black light)

Most of us are exposed to large amounts of UVA throughout our lifetime. UVA rays have a wave length of 320 – 400 nm and account for up to 95 percent of the UV radiation reaching the Earth’s surface. Although they are less intense than UVB, UVA rays are 30 to 50 times more prevalent. They are present with relatively equal intensity during all daylight hours throughout the year, and can penetrate clouds and glass.

UVA is the dominant tanning ray, and we now know that tanning, whether outdoors or in a salon, causes cumulative damage over time. A tan results from injury to the skin’s DNA; the skin darkens in an imperfect attempt to prevent further DNA damage. These imperfections, or mutations, can lead to skin cancer.

UV-B (Ultraviolet B, UVB or medium wave)

UVB has a wave length of 290 – 320nm and affects the outer layer of skin, the epidermis, and is the primary agent responsible for sunburns. It is the most intense between the hours of 10:00 am and 2:00 pm when the sunlight is brightest. It is also more intense in the summer months accounting for 70% of a person’s yearly UVB dose. UVB does not penetrate glass

UV-C (Ultraviolet C, UVC, short wave, or germicidal)

UV-C radiation is light at a wavelength of between 280 and 100nm. The wavelength that is primarily responsible for destroying micro-organisms is 253.7nm. This has the greatest effect on the genetic make-up of the micro-organism’s nucleus. Our UV-C emitters are designed to emit light on a spectral line of exactly 253.7 nm, whilst at the same time preventing the unwanted formation of ozone, which occurs in other units. The desired effect is achieved by using low-pressure mercury vapour lamps.

Furthermore, special glass is used which prevents the emission of wavelengths below 200nm that are responsible for the formation of irritant ozone gas. Radiation traps in the system casings ensure that no radiation can escape outside. This means that UV-C radiation can be used without any health risk to people or impairment of food products.