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These two changes combine to allow the 253.7 nm ultraviolet light produced by the mercury arc to pass out of the lamp unmodified (whereas, in common fluorescent lamps, it causes the phosphor to fluoresce, producing visible light). Germicidal lamps still produce a small amount of visible light due to other mercury radiation bands.
A low-pressure mercury-vapor discharge tube floods the inside of a biosafety cabinet with shortwave UV light when not in use, killing microbes on irradiated surfaces. Ultraviolet germicidal irradiation (UVGI) is a disinfection technique employing ultraviolet (UV) light, particularly UV-C (180–280 nm), to kill or inactivate microorganisms ...
Occupational exposures to UV light occur in welding and brazing operations, for example. Excessive exposure to natural or artificial UV-radiation means immediate (acute) and long-term (chronic) damage to the eye and skin. Occupational exposure limits may be one of two types: rate limited or dose limited.
These lamps emit ultraviolet light with two peaks in the UVC band at 253.7 nm and 185 nm due to the mercury within the lamp, as well as some visible light. From 85% to 90% of the UV produced by these lamps is at 253.7 nm, whereas only 5–10% is at 185 nm. [39] The fused quartz tube passes the 253.7 nm radiation but blocks the 185 nm wavelength.
UVC or Ultraviolet Germicidal Irradiation is a function used in modern air conditioners which reduces airborne viruses, bacteria, and fungi, through the use of a built-in LED UV light that emits a gentle glow across the evaporator. As the cross-flow fan circulates the room air, any viruses are guided through the sterilization module’s ...
The UV-B flux is 2–4 times greater during the middle 4–6 hours of the day, and is not significantly absorbed by cloud cover or up to a meter of water. [47] Ultraviolet light, specifically UV-B, has been shown to cause cataracts and there is some evidence that sunglasses worn at an early age can slow its development in later life. [18]
A biosafety cabinet (BSC)—also called a biological safety cabinet or microbiological safety cabinet—is an enclosed, ventilated laboratory workspace for safely working with materials contaminated with (or potentially contaminated with) pathogens requiring a defined biosafety level.
The Health Protection Agency of the United Kingdom recommend that in situations requiring close proximity to the light source, open (single envelope) CFLs be replaced with encapsulated (double envelope) CFLs. [13] In 2009, Natural Resources Canada released a report [14] describing the possible UV exposure from several types of lamps. The report ...