Air Disinfection for Airborne Infection Control with a Focus on COVID-19: Why Germicidal UV is Essential†

Abstract

Aerosol transmission is now widely accepted as the principal way that COVID-19 is spread, as has the importance of ventilation-natural and mechanical. But in other than healthcare facilities, mechanical ventilation is designed for comfort, not airborne infection control, and cannot achieve the 6 to 12 room air changes per hour recommended for airborne infection control. More efficient air filters have been recommended in ventilation ducts despite a lack of convincing evidence that SARS-CoV-2 virus spreads through ventilation systems. Most transmission appears to occur in rooms where both an infectious source COVID-19 case and other susceptible occupants share the same air. Only two established room-based technologies are available to supplement mechanical ventilation: portable room air cleaners and upper room germicidal UV air disinfection. Portable room air cleaners can be effective, but performance is limited by their clean air delivery rate relative to room volume. SARS-CoV-2 is highly susceptible to GUV, an 80-year-old technology that has been shown to safely, quietly, effectively and economically produce the equivalent of 10 to 20 or more air changes per hour under real life conditions. For these reasons, upper room GUV is the essential engineering intervention for reducing COVID-19 spread.

Figure 1

Unpublished experiment by Volchenkov and Jensen comparing upper room UV to mechanical ventilation and three different room air cleaners, the Potok model having been used in the Soyuz Space capsule. (Top) The cost of one ACH was calculated for each intervention. (Bottom) Ventilation is set as 1 for comparison purposes, and UV was more than 9 times cost‐effective.