Upper Room systems began to be installed with people present inside the rooms since the 40’s. First they were used in Operating rooms, and because good disinfection results and safety, installations were extended to other Hospital areas where risk of airborne infections. Infection rate between persons was reduced significantly (1). Since this stage of technical knowledge , Upper Room Ultraviolet Germicidal Irradiation, was applied to suburban schools in Philadelphia during measles outbreak. It was observed, that students with Upper Room in Classrooms practically were not infected by measles (2)
During 1957 Influenza pandemic, Upper Room UVGI systems were successfully employed in North American Hospitals to reduce cross infections at the same moment that Influenza was recognized as airborne (3). In the 60’s, Riley & Wells, authors of “droplet nuclei” concept, showed: Tuberculosis was airborne transmitted by droplet nuclei coming from infected persons and the use of Upper Room in their experiences reach sterilization values of LOG 6 and LOG 9, using respectively 17W and 43 W powers (4,5).
Since 70’s until the end of 80’s, interest for Upper Room Ultraviolet C systems decayed by the appearance of antibiotics for TB. It originated a time where the predominant thought was that known infectious diseases were going to be controlled by immunization and antibiotics. Reality hit this conception when TB antibiotic resistant strains appeared. This fact was accompanied with the increase in the number of person with AIDS, so the situation was even more dramatic (6,7). With this situation, Upper Room System revival as key for infection prevention (8,9). The state of knowledge regarding Upper Room grew intensively: Ultraviolet Disinfection Evaluations in built aerosol chambers (10), test room models, physical variables affecting the system (ventilation, Humidity, Temperature), fluid computational analysis, math models to predict Upper Room fixture irradiances (12), occupational safety (13), maintenance guides, installing precision models, safety evaluation, etc.
Upper Room is a very well studied Air Disinfection System for Airborne Infectious Agents, Effective, Safe, and widely used.
In 2009 CDC center published a comprehensive guide for the use of Upper Room Air Disinfection System in Health Facilities (14). Nowadays, World Health Organization, considers Upper Room Ultraviolet Germicidal Irradiation, as standard of care in Hospital Tuberculosis Prevention and Control.
Proved Effectiveness avoiding airborne infections among persons, with operational safety in the presence of people, let Upper Room be extended to other places rather than Hospitals: Shopping centers, Airports, Nursing homes, Shelters, Office Buildings, Schools, Institutes, Universities, Supermarkets, Metro Stations and Railway stations, Auditoriums, Sport centers, Restaurants, etc
Today, Upper Rooms long established potential inactivating airborne viruses or bacteria since more than 80 years, with demonstrated safety for people, let this Air Disinfection System be considered as a true effective solution against COVID-19
(1) Goldner JL, Moggio M, Beissinger SF, McCollum DE. Ultraviolet light for the control of airborne bacteria in the operating room. Ann N Y Acad Sci 1980;353:271-84.
(2) Wells WF, Wells MW, Wilder TS. The environmental control of epidemic contagion I: an epidemiologic study of radiant disinfection of air in day schools. Am J Hyg 1942;35:97-121 & Wells WF. Airborne contagion and air hygiene: an ecological study of droplet infections. Cambridge (MA): Harvard University Press 1955
(3) McLean RL. The mechanism of spread of Asian influenza: general discussion. Am Rev Respir Dis 1961(2 Pt 2);83:36-8.
(4) Riley RL, Mills CC, Nyka W, Weinstock N, Storey PB, Sultan LU,et al. Aerial dissemination of pulmonary tuberculosis: a two-year study of contagion in a tuberculosis ward. Am J Hyg 1959;70:185-96.
(5) Riley RL, Mills CC, O’Grady F, Sultan LU, Wittstadt F, Shivpuri DN. Infectiousness of air from a tuberculosis ward. Ultraviolet irradiation of infected air: comparative infectiousness of different patients. Am Rev Respir Dis 1962;85:511-25.
(6) McAdam JM, Brickner PW, Scharer LL, Crocco JA, Duff AE. The spectrum of tuberculosis in a New York City men’s shelter clinic (1982–1988). Chest 1990;97:798-805.
(7) Vincent RL. Airborne disease control: measurement of ultraviolet germicidal irradiation (UVR) in high-risk environments. In: Matthes R, Sliney D, editors. Measurements of optical radiation hazards (ICNIRP 6/98; CIE x016-1998). München: Märkl-Druck; 1998. p. 369-86.
(8) Nardell EA. Ultraviolet air disinfection to control tuberculosis in a shelter for the homeless. In: Kundsin RB, editor. Architectural design and indoor microbial pollution. New York: Oxford University Press; 1988. p. 296-308.
(9) Stead WW, Yeung C, Hartnett C. Probable role of ultraviolet irradiation in preventing transmission of tuberculosis: a case study. Infect Control Hosp Epidemiol 1996;17:11-3.
(10) Miller SL, Macher JM. Evaluation of a methodology for quantifying the effect of room air ultraviolet germicidal irradiation on airborne bacteria. Aerosol Sci Technol 2000;33:274-95.
(11) Dumyahn T, First M. Characterization of ultraviolet upper room air disinfection devices. Am Ind Hyg Assoc J 1999;60:219-27.
(12) First MW, Weker RA, Yasui S, Nardell EA. Monitoring human exposures to upper-room germicidal ultraviolet irradiation. J Occup Environ Hyg 2005;2:285-92.
(13) Nardell EA, Bucher SJ, Brickner PW, Wang C, Vincent RL, Becan-McBride K, et al. Safety of upper-room ultraviolet germicidal air disinfection for room occupants: results from the Tuberculosis Ultraviolet Shelter Study. Public Health Rep 2008;123:52-60.
(14) Centers for Disease Control and Prevention (US). Environmental control for tuberculosis: basic upper-room ultraviolet germicidal irradiation guidelines for healthcare settings. Atlanta: CDC, National Institute for Occupational Safety and Health (US); 2009. DHHS (NIOSH) Publication No. 2009-105.
(15) Who Guidelines on Tuberculosis Infection Prevention & Control 2019
