Q: Is there UVGI that can kill the virus? What is the best way to apply UVGI in a recirculating airstream?
A: UVGI bulb fixtures are available for easy retrofit to duct systems and have been shown to be effective at killing the virus. Duct mounted UVGI in a large scale, blind study conducted over 1 year with alternating periods of operation showed significant improvement in building occupant health (especially among people with respiratory sensitivities). Installing UVGI fixtures after the return filter and before heating/cooling coils will also provide coil drain pan sanitation that has been shown to provide relief for respiratory-sensitive building occupants (e.g., asthma, allergenic rhinitis, etc.). Installing UVGI just downstream of AC coils is also good, especially if the light can "see" upstream to the cooling coils and drain pan. See this white paper from UV Resources for a description of UVGI in ducts and duct placement instructions.
Q: Can you provide examples of facilities that have used UVGI airstream treatment?
A: UVGI is very common in hospital HVAC units and laboratory AHUs that test microbes.
Q: Should we be considering UVGI surface sanitization in addition to disinfectants to clean surfaces?
A: There are UVGI lamp fixtures that can be mounted on ceilings and walls to sanitize surfaces in a room. In one study exploring UVGI surface sanitation, microbial contamination on surfaces was reduced from 30% to 3%. Some UVGI lamp fixtures are even portable. These systems are often used in medical facilities, but could also be considered in places that frequently serve large groups of people.
Q: Should we be considering needle point bipolar ionization products (no ozone), such as GPS, PlasmaAir?
A: While ASHRAE has investigated UVGI (ultraviolet germicidal irradiation) for air sanitation, limited research is available on ionization effectiveness and ionization design principles, to our knowledge.
Filtration & air cleaning
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