Upper Room UV Systems

Abstract

Upper Room UV systems, sometimes called Upper Air systems, create a germicidal zone of UV rays that are confined to the upper portion of a room, known as the UV zone or stratum. Air that enters into this field is disinfected, along with any exposed surfaces. UV exposure levels in the lower room are maintained below the ACGIH 8-hour exposure limit of 30 J/m² (broadband UV) or 60 J/m² (254 nm). Upper Room systems operate continuously in occupied areas and if properly designed and installed are safe (see photo above, image courtesy of Lumalier, Memphis, TN). They can be a relatively simple and effective means of controlling airborne infection and can be cost-effective for many types of facilities, including hospital applications, waiting rooms, prisons, and homeless shelters. Upper Room UV may be preferred over other devices since they are passive (no moving parts), have modest costs, and low energy consumption. One of the stated advantages of Upper Rooms systems is that they intercept microbes inside the room where they may be generated by occupants, thereby controlling infection at the source (First et al. 1999). Continuous upper air UV disinfection is considered to be the most practical method in resource-limited countries where mechanical systems are often lacking and in cold climates where energy losses from high air turnover rates are prohibitive (WHO 1999).