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A germicidal lamp (also known as disinfection lamp or sterilizer lamp) is an electric light that produces ultraviolet C (UVC) light. This short-wave ultraviolet light disrupts DNA base pairing , causing formation of pyrimidine dimers , and leads to the inactivation of bacteria , viruses , and protozoans .
The location of 'far-UVC' radiation (200-235 nm) in the electromagnetic spectrum. Far-UVC is a type of ultraviolet germicidal irradiation being studied and commercially developed for its combination of pathogen inactivation properties and reduced negative effects on human health when used within exposure guidelines.
Lamp age or fouling or outages (reduction in UV intensity) Bulbs require periodic cleaning and replacement to ensure effectiveness. The lifetime of germicidal UV bulbs varies depending on design. Also, the material that the bulb is made of can absorb some of the germicidal rays. Lamp cooling under airflow can also lower UV output.
Germicidal lamps are simple low-pressure mercury vapor discharges in a fused quartz envelope. Gas-discharge lamps are a family of artificial light sources that generate light by sending an electric discharge through an ionized gas, a plasma. Typically, such lamps use a noble gas (argon, neon, krypton, and xenon) or a mixture of these gases.
The lamp's electrodes are typically made of coiled tungsten and are coated with a mixture of barium, strontium and calcium oxides to improve thermionic emission. A germicidal lamp uses a low-pressure mercury-vapor glow discharge identical to that in a fluorescent lamp, but the uncoated fused quartz envelope allows ultraviolet radiation to transmit.
Unfiltered light from a high-pressure lamp is rich in UVC used in germicidal lamps, for water purification, but it damages human skin. The contents of a high-pressure lamp are inert gas (such as argon) and mercury. [2] There are no phosphors used, and the mercury is clearly visible if it is not in a gaseous state.
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The diseases UV-B lamps treat are psoriasis, [2] vitiligo, lichen planus, atopic dermatitis (eczema), and other skin diseases. Thousands of dermatology clinics around the world treat skin ailments using UV-B lamps. Many people who suffer from psoriasis or other skin diseases have their own UV-B lamp at home.