Indoor Air Disinfection: Answering Questions About Germicidal Ultraviolet Lights

Occupational health professionals (OHPs) use the National Institute for Occupational Safety and Health’s (NIOSH) “Hierarchy of Controls” to prioritize efforts to reduce workplace hazards. Hazards that are eliminated or “engineered” out minimize the need for employees to remember safety behaviors such as standing 6 feet. away from co-workers. In practice, occupational hazard control incorporates layers of protection, including elimination, substitution, engineering and administrative controls, and personal protective equipment.

Engineering controls such as ventilation and air disinfection with germicidal ultraviolet (GUV) light have the potential to work in tandem to prevent transmission of SARS-CoV-2 in indoor areas, including workplaces (U.S. Environmental Protection Agency [EPA], 2022). NIOSH (2009) has guidelines for using GUV in hospitals to prevent transmission of tuberculosis. Key occupational/environmental health scientists and leaders have called for more attention to engineering controls such as GUV to prevent “super-spreader” events in indoor spaces (Milton et al., 2022).

Consequently, OHPs may get questions about GUV and other types of disinfection for inactivating infectious particles in indoor air. Employers who require employees to attend large gatherings such as meetings, retreats or conferences, or owners of large hotels or conference centers that hold meetings or banquets where food is served, and potentially other workplaces such as restaurants, long-term care, hospitals, schools, and entertainment venues may consider GUV light installations. Occupational health professionals should anticipate questions about effectiveness, safety, installation, maintenance, and cost. Several resources will assist OHPs to keep up with this rapidly evolving technology to participate in decisions about purchasing and using GUV in the workplace: for example, questions like, “Is anyone already using GUV?” The University of Utica recently decided to install upper room GUV in classrooms to protect the faculty and students (University of Utica Health Safety, 2020). The Tennessee Valley Authority EnergyRight (2022) is offering customers incentives to install GUV in their ventilation ducts to reduce the risk of transmitting infectious diseases. Furthermore, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), which publishes indoor air standards for ventilation, is updating its guidance to include GUV. They will soon address GUV in air ducts, upper room GUV and UVC, or far-UV for surface and air decontamination in more detail (American Society of Heating, Refrigerating and Air-Conditioning Engineers [ASHRAE], 2022).

Many associate UV light with sunburn and skin cancer, which comes from UVA, which is one of three UVA types (A, B, and C). Most UVB, also from the sun, is filtered out in the atmosphere., while UVC involves the use of lamps for surface and air disinfection (National Academies of Sciences, Engineering, and Medicine, 2022). To date, the Occupational Safety and Health Administration (OSHA) does not have a specific UV regulation; however, the American Conference of Governmental Industrial Hygienists (ACGIH) has a Threshold Limit Value (TLV) for GUV that is being revised (upward for skin and eyes) based on reexamination of the evidence for human health effects (Sliney & Stuck, 2021). The TLV for GUV installations is the first place for OHPs to start protecting employees from possible skin and eye health effects; you must also ensure that the installer or industrial hygienist can confirm the dose of the UVC fixture. Specific information about the distance between the employees and the GUV source, the number of hours per day working in the space, and whether vulnerable populations need specific protections must also be determined and communicated to supervisors. Studies are very promising that far-UVC (222 nm) is safe for most individuals for the entire workday (Eadie et al., 2022), but close collaboration with industrial hygienists, product experts, facilities engineers, and government experts is warranted.