UV-B lamps are lamps that emit a

spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors ...

ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation ...

light with wavelengths ranging from 290–320 nanometers. This spectrum is also commonly called the biological spectrum due to the human body's sensitivity to light of such a wavelength. UV-B light does not tan the skin very much, compared to the UV-A lamps that are used in

tanning bed Indoor tanning involves using a device that emits ultraviolet radiation to produce a cosmetic tan. Typically found in tanning salons, gyms, spas, hotels, and sporting facilities, and less often in private residences, the most common device is a ho ...

Treating skin diseases

The main diseases that are treated with UV-B lamps are

psoriasis Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by raised areas of abnormal skin. These areas are red, pink, or purple, dry, itchy, and scaly. Psoriasis varies in severity from small, localized patches to complete ...

lichen planus Lichen planus (LP) is a chronic inflammatory and immune-mediated disease that affects the skin, nails, hair, and mucous membranes. It is not an actual lichen, and is only named that because it looks like one. It is characterized by polygonal, fla ...

and atopic dermatitis (eczema).,

vitiligo Vitiligo is a disorder that causes the skin to lose its color. Specific causes are unknown but studies suggest a link to immune system changes. Signs and symptoms The only sign of vitiligo is the presence of pale patchy areas of depigmen ...

(loss of skin color) and some other skin diseases. There are thousands of dermatology clinics around the world that treat skin ailments with UV-B lamps. Many people who suffer from psoriasis or other skin diseases have their own UV-B lamp for home treatment. A small lamp is used to treat limited areas of the skin, while full body cabins are available in clinics and hospitals. Overexposure to UV-B light can burn the skin, so the exposure time must be regulated by a timer that turns off the lamp.

Increasing vitamin D3

When the skin is exposed to UVB light of 297 nanometer, the cholesterol in the skin is transformed into

vitamin D3 Cholecalciferol, also known as vitamin D3 and colecalciferol, is a type of vitamin D that is made by the skin when exposed to sunlight; it is found in some foods and can be taken as a dietary supplement. Cholecalciferol is made in the skin f ...

. The skin needs only 50-100 mili joules of 297 nanometer light to generate vitamin D3. 15 minutes of strong sunshine every day is usually considered enough. In Northern European countries especially in the winter when sunlight is scarce, pregnant women may receive UVB light in clinics to assure that their babies have an adequate amount of vitamin D3 when born. Animals need UV-B light to produce vitamin D3 and strong bones. If the lamp does not produce exactly 297 nanometer it will not help. Fluorescent or filament lamps do not produce 297 nanometer and they are not beneficial for reptiles for vitamin D3, even that they generate UVA and some UVB that is not 297 nanometer. The skin does not need UVA light or any UVB light that is not 297 nanometer, and this light can harm the skin.

Cancer risks

UV-B treatments for treating skin diseases (psoriasis, vitiligo, atopic dermatitis, etc.) are given in a very low dosage. The treatments take only few minutes. The maximum dose of broadband UV-B is 0.5 Joules per treatment. The maximum dose for narrowband UV-B is 3 Joules per treatment. This low dosage does not increase the risk of skin cancer and UV-B phototherapy remains a very safe treatment. Research citing ten years of experience with phototherapy in Yonsei Medical Center has not revealed any cases of malignancy in the skin. Too much UV

radiation of an undesirable wavelength may lead to

direct DNA damage Direct may refer to: Mathematics * Directed set, in order theory * Direct limit of (pre), sheaves * Direct sum of modules, a construction in abstract algebra which combines several vector spaces Computing * Direct access (disambiguation), ...

, sunburn, and skin cancer. In contrast to exposure to UV-B light given at low dosage, it was found that UV-A light increases the risk of skin cancer because of the problematic wavelength and because it is given in a much higher dosage.

References

{{reflist Types of lamp Light therapy