• UV lights must be turned off whenever the room is occupied.
• Post a warning sign on the front of the BSC indicating the presence of UV light hazards.
• The sign must say CAUTION: Turn off UV light before working.
• Turn the UV light off after 15 minutes. If UV lights will be used overnight or for extended periods of time while staff are not present, the sign should be posted on the  outside of the closed door of the room.
• For biological safety cabinets with sashes that close, the light must only be used when the sash is fully closed. Sash alarms or mechanisms ensuring this feature may not  be disabled.
• All items to be removed from the BSC and surfaces of the BSC must be decontaminated prior to UV light use.

• Painful eye and skin burns
• Prolonged exposure to UV light may cause cancer
• Damaging exposure levels exist well after the output of the lamp bulb has dropped below the biocidal level.
• Deterioration of some plastics, including tubing in a BSC
• This can be dangerous if you are using a touchplate microburner (Touch-Matic) with natural gas

Never rely on UV irradiation alone to disinfect a contaminated work area. UV is:

• • Not effective on porous materials that are opaque to the light such as wood or foam.
  • Ineffective if a microbe is protected by dust, dirt, or organic matter.
  • Affected by the accumulation of dust and dirt on the bulb surface.
  • Effective only in direct line of sight.
  • UV does not work in shadowed areas, penetrate into cracks or through the grill work of a BSC.
  • The spill area under the work surface of a BSC is a favorite hide out for fungal spore and hardy
    bacteria.

• Humidity – above 70 percent germicidal activity is drastically reduced.
• Optimum temperature for output is 77-80°F. Temperatures below this optimum temperature result in reduced  output of the germicidal wavelength. Moving air tends to cool the lamp below its optimum operating temperature and therefore results in reduced output.
• Age – effective UV radiation emitted from the lamps decreases with age. The UV lamp bulb remains lit long after the germicidal effectiveness is gone. Ultraviolet light intensity should be checked or replaced annually to ensure the emitted intensity is sufficient for germicidal activity.

• Turn off UV lamps while the lab is occupied. The stainless steel interior of the BSC can reflect potentially hazardous illumination out of the opening of the cabinet.
• Never have the UV lamp on while an operator is working in the cabinet.

• Decontaminate all work surfaces with an approved disinfectant, such as a freshly prepared 1:10 dilution of bleach.
• Turn the fan off and close the sash, if possible, when the UV lamp is on.

• Clean UV lamp bulbs weekly by turning off the UV lamp then wiping off the surface of the room temperature lamp bulb with 70% alcohol. This will remove dust and  dirt that can block the germicidal effectiveness of the light.
• Before replacing bulbs, clear the BSC of equipment and material, and disinfect it with a freshly prepared 1:10 dilution of bleach (20 minute contact time) and then  remove the bleach residue with 70% ethanol.
• Install the bulb with gloved hands to prevent oil build up.
• Disinfect lamp bulbs before disposal. Lamps must be disposed as hazardous waste because they contain mercury. A waste pickup can be arranged through the OEHS LMS.