Safety Tips for Using Germicidal Lamps
What are
Germicidal Lamps?
Germicidal lamps emit radiation in the UV-C portion of the
ultraviolet (UV) spectrum, which includes wavelengths between 100 and 280
nanometers (nm). The lamps are used in a
variety of applications where disinfection is the primary concern, including
air and water purification, food and beverage protection, and sterilization of
sensitive tools such as medical instruments.
Germicidal light destroys the ability of bacteria, viruses, and other
pathogens to multiply by deactivating their reproductive capabilities. The average bacteria may be killed in 10
seconds at a distance of 6 inches from the lamp. The wavelength with the greatest
effectiveness is 253.7 nm, which defines the germicidal lamp category with
optimized wavelength for maximum absorption by nucleic acids. Germicidal lamps that generate energy
wavelengths shorter than 250 nm (particularly 185 nm) are very effective in
producing ozone, which is required for certain applications to oxidize organic
compounds.
Hazard
and Risks from Germicidal Lamp UV Radiation
UV radiation (UVR) used in most germicidal bulbs is harmful
to both skin and eyes, and germicidal bulbs should not be used in any fixture
or application that was not designed specifically to prevent exposure to humans
and animals.
UVR is not felt immediately; in fact, the user may not
realize the danger until after exposure has caused damage. Symptoms typically occur 4 to 24 hours after
exposure.
The effects on skin are of two types: acute and
chronic. Acute effects appear within a
few hours of exposure, while chronic effects are long-lasting and cumulative
and may not appear for years. An acute
effect of UVR is redness of the skin called erythema (similar to sunburn). Chronic effects include accelerated skin
aging and skin cancer.
UVR is absorbed in the outer layers of the eye- the cornea
and conjunctiva. Acute overexposure
leads to a painful temporary inflammation, mainly of the cornea, known as
photokeratitis. Subsequent overexposure
to the UV is unlikely because of the pain involved. Chronic exposure leads to an increased risk
of certain types of ocular cataracts.
Working unprotected for even a few minutes can cause
injury. It is possible to calculate the
threshold for acute effects and to set exposure limits. It is not possible, however, to calculate
threshold for chronic effects; therefore, because no exposure level is safe,
exposure should be reduced as much as possible.