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Jun
30

Upper room ultraviolet germicidal irradiation (UVGI) systems

Upper room ultraviolet germicidal irradiation (UVGI) systems kill viruses and other microbes in indoor air using low-wavelength ultraviolet light above people.

Upper-room UVGI diagram displaying a disinfection zone of UV energy that is located above people in the rooms they occupy.

Image source: Centers for Disease Control and Prevention (CDC)

These systems are UV light fixtures that kill or inactive germs in the air in the upper part of a room. They do not remove particles from the air, and so aren’t effective at cleaning pollutants like exhaust, dust, or smoke.

Upper room UVGI is not recommended for every facility. Consult a UVGI expert from a reputable UVGI vendor (contact a local HVAC company for assistance) before installing an upper room UVGI system and review the considerations below.

Direct exposure to UV light can be dangerous. Do not attempt to self-design or use a homemade upper room UVGI system. Placing and installing an upper room UVGI unit should always be done in consultation with the manufacturer and your building engineer to ensure safety.

Is upper room UVGI right for your facility?

  • Upper room UVGI systems are best for spaces where there is little to no option for ventilation or air filtration.
  • Ceilings should be at least 8 feet tall, though some units may be effective at 7 feet. Depending on the size of the space, you may need more than one system.

Maintaining your upper room UVGI system

  • Replace UV lights every 1-2 years. Schedule regular bulb cleanings and replacement.
  • Follow the manufacturer's instructions when cleaning and replacing bulbs to avoid accidental UV exposures.
  • UV bulbs contain mercury and should be handled with care. Staff should be informed of what to do if a UV light bulb breaks on site and how to safely dispose of used lamps. EPA provides guidance on how to clean up a broken bulb.
  • You may need to make seasonal adjustments to maintain relative humidity (RH) at 60% or less and room temperature between 68°F to 75°F (20°C to 24°C), which are the optimal conditions for low-pressure mercury lamps used in upper room UVGI systems.

Upper room UVGI safety

  • Only use upper room UVGI systems. Other UV devices are not recommended for cleaning the air.
  • Installation should be done by your building engineer, a certified electrician, and/or a qualified contractor.
  • As an added safety measure, building maintenance staff should use a radiometer or UV dosimeter indicator cards every few months to ensure UV light intensity in the upper and lower room spaces is correct and that the UV lamp is performing as it should.
  • Consult a professional who is knowledgeable about upper room UVGI systems and system installation before procuring and installing the system. There are a limited number of people properly trained in the design of upper room UVGI systems. Companies that manufacture, supply, and install units will recommend unit placement and provide experts who can install units in your area. Be prepared to provide companies with the following information:
    • "As-builts" (diagrams) of the building.
    • Square footage per room.
    • Ceiling heights per room.
    • Number of people and activities per room (e.g., number of beds in sleeping spaces, are there bunk beds, etc.).

Additional resources

For more information see the CDC's guidance on the use of upper room UVGI, which discusses its utility for limiting the spread of COVID-19.

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