While the Covid-19 pandemic continues to ebb and flow, I have been working on return to work plans and the various strategies and technologies that will allow companies to do it safely. One such technology being considered is UV disinfection and a question I have been hearing often is:
A dizzying array of applications and products are available both now and in the near future. This article documents relevant resources so that it can be shared and used by other facilities professionals currently in the thick of reconfiguring and renovating the offices, labs and work spaces under their charge.
About GUV Lamps
Even prior to the pandemic, Germicidal UV (GUV) lamps have been used for disinfection. However, due to its potential harmful effects on the human body, particularly the skin and eyes, its use has been limited to controlled conditions like within water purification equipment or biosafety cabinets where operators are trained and follow protocols when working around UV energy.
If this technology is to be extended to the wider work space, careful consideration and effective engineering and administrative controls (e.g. door interlocks,occupancy sensors, signage, training) need to be employed to prevent accidental exposure. See further recommendations on safe use in the resources section below.
GUV lamps emit UV radiation which can kill bacteria, spores and inactivates viruses. Note however, that not all UV light have these properties. Only specific wavelengths, applied at the right dosages, are able to have these effects.
To irradiate a space, GUV lamps can be installed in a variety of ways: as a lighting fixture in the ceiling, installed as part of the ventilation system to disinfect the air supply or be introduced into a room as mobile systems that are either manually or robotically moved into place.
The following are examples of the various ways in which GUV can be used to disinfect work places:
Mobile Sterilization Systems
These “light towers” consist of UV lamps mounted vertically atop a wheeled base. Units can either be wheeled manually into the space or run on a handsfree system that is either remotely controlled or moves autonomously. The UV light is turned on and disinfects surfaces that are in direct line of sight.
When these are in operation, the room should be empty so the technology should be used in conjunction with controls such as occupancy detection, door interlocks and controlled access procedures and signage.
In this technique, the UV light disinfects the room air rather than surfaces directly. This has the benefit of lowering the risk of UV irradiation on room occupants but it is a more indirect method and would not disinfect surface contamination.
Variations in this category include:
- Upper Air UV Fixtures – installed high on the ceiling or on a wall, the UV light disinfects supply air coming out of ceiling registers and also as air circulates towards the top of the room thereby continuously disinfecting the space. The high mounting position and louvers in the fixtures that direct the light upwards minimizes the risk of UV exposure to room occupants.
- UV Air Movers – these are air recirculating units that utilize a blower to pull room air into the unit where the air is then irradiated and then blown back out into the room. The fixture can be mounted on the ceiling, floor or wall.
- HVAC UV Fixtures – UV lamps are installed within the air handling system to disinfect the air within the ventilation system. As the UV lamps are within the HVAC system, there is a reduced risk of exposure. Maintenance personnel will need to be trained and follow appropriate safety procedures when servicing equipment.
UV light fixtures are installed in the ceiling and disinfect the surfaces in direct line of sight. Like mobile systems, these lights should only be turned on when the room is empty of people. As such its use should be in conjunction with controls such as occupancy detection, door interlocks and controlled access procedures and signage.
Source: Cooper Lighting
Promising new studies from Columbia University are suggesting that lamps that emit “Far-UVC” could be more safely used around humans. The light emitted in this wavelength is posited to be able to harm viruses and bacteria but not penetrate the skin and eyes.
More studies need to be done to confirm this but this technology could be a gamechanger and enable wide areas to be disinfected continuously. No commercial product is available currently but Ushio is currently working on a product slated for late 2020 release.
Each technique has its pros and cons and the optimum implementation will depend on the unique features and conditions of each space. Still, the relative strengths and weaknesses of each technique can be summarized in the table below
The mobile systems are quickest to implement as they do not require any changes to the room or systems whereas the air supply or fixture applications will require some modification to the HVAC or room lighting systems.
Because the supply air methodology irradiates the air rather than directly at surfaces, it is relatively lower risk (in terms of exposure to skin and eyes) than the other 2 methods.
The supply air methodology also has the potential to be the lowest cost application especially when applied to the HVAC system as the UV disinfection system is centrally located in one or a few locations while the fixtures will need to be installed in every room while UV robots cost $80,000-$90,000 per robot.
One might then conclude that supply air is the way to go however it does not directly disinfect surfaces only the air in the room. Also, it does it at the rate of exchange of the room air so its action is more delayed.
In the era of Covid-19, building managers are looking to UV disinfection as one of the measures to enable return of the workforce. There are a variety of options from mobile light towers to built in fixtures that can be employed.
Which technique or combination of techniques that is ultimately used will depend on the use case, degree of retrofit countenanced, availability, schedule and budget for each particular space.
If you would like to have a conversation on return to work planning for your specific case, please get in touch.
Note that the products listed here are informational only and do not constitute an endorsement or an approval by Crew Universal of any of the products.
- IUVA Fact Sheet on UV Disinfection for COVID-19
- Safety Tips for Using Germicidal Lamps – Lawrence Berkeley Labs Lessons Learned
- Germicidal UltraViolet Disinfection in the Days of Covid-19 – Illuminating Engineering Society
- Advice for the selection and operation of equipment for the UV disinfection of air and surfaces – IUVA
- Cooper Lighting Solutions GUV Technology Primer
- Dental practices consider using UV light tech to safely reopen – CNBC
- Far-UVC Light Safely Kills Airborne Coronaviruses – Columbia University
- Are UltraViolet Sanitizing Lights Safe for Humans? – Discover Magazine
- Back to Normal: An Old Physics Route to Reduce SARS-CoV-2 Transmission in Indoor Spaces