Applications for Ultraviolet Germicidal Irradiation (UVGI) in Hospital Isolation Anterooms

摘要

Certain pathogens are transmitted through air by respiratory droplets that desiccate shortly after emission and form droplet nuclei. Droplet nuclei are small (<5.0um) and can remain suspended in the air, creating a pathway between an infected and susceptible person. This process is called 'airborne transmission'. Patients with an airborne infectious disease (e.g. tuberculosis, varicella, etc.) are separated from the healthcare environment by an Airborne Infection Isolation Room (AIIR). AMRs have special features to effectively contain and remove airborne pathogens, including a -2.5Pa air pressure relationship and directional airflow away from adjoining healthcare spaces. Directional airflow, however, may be disrupted and even reversed by door opening motion and the movement of people and equipment into and out of the AIIR. Ultraviolet germicidal irradiation (UVGI) is a disinfection method that uses short-wavelength ultraviolet (UV-C) light to kill or inactivate airborne microorganisms. UVGI has proven to be among the least energy intensive and most cost-effective methods of disinfection. However, germicidal UV wavelengths can produce ozone and prolonged exposure can cause damage to the skin and eyes. As a result, continuous exposure to germicidal UV may be limited to 0.2uW/cm2 for a 8-hour period, or in some cases, prohibited entirely. This paper explores the use of UVGI in unoccupied anterooms as an additional airborne infection control measure. Specifically, this research highlights the results of both experimental and computation studies that explore air exchange and particle movement between isolation rooms and adjacent hospital corridors, and, the potential use of occupancy controlled UVGI in isolation anterooms and vestibules.