Dynamic disinfection effect of the upper-room 222 nm ultraviolet radiation on the air in the emergency department in a tertiary general hospital in Beijing, China

ObjectiveTo evaluate the dynamic disinfection effect of the upper-room 222 nm ultraviolet radiation on the air in different areas of the emergency department, and to provide references for a new solution of air disinfection that man-machine coexisted in the medical and healthcare institutions.MethodsThe upper-room 222 nm ultraviolet radiation air sterilizers were installed at a height of 2.3‒2.6 m from the ground in the observation room, computed tomography (CT) scanning room, rescue room and consulting room of the emergency department in Beijing Tiantan Hospital, Capital Medical University . The test area was divided into a 222 nm ultraviolet group and a control group according to whether the 222 nm ultraviolet germicidal air disinfection was conducted or not. The experimental group started air disinfection at 8:00 a.m., and the air sampling was conducted from 9:00 a.m. to 16:00 p.m., with a 10 min sampling interval of every 1 hour. While the control group only collected air sample with the same air sampling method used in the experimental group, without air disinfection. The air microbial sampler with six-level sieve impingement was used for the air sampling, and the differences in the total number of airborne bacterial colonies were compared between the two groups.ResultsA total of 128 air samples were collected in the trial, of which 64 were from the experimental group and 64 from the control group. The total number of airborne bacterial colonies in the experimental group was lower than that in the control group (all P<0.001), and was maintained at a lower level throughout the entire period. The killing rate of 222 nm ultraviolet radiation to airborne microorganisms was approximately 55.76% to 76.33% in different sampling areas. The qualified rates of the total number of dynamic airborne bacterial colonies in the observation room, rescue room and consulting room were improved from 12.50%, 37.50% and 25.00% to 81.25%, 100.00% and 100.00%, respectively (all P<0.001). Over 62.50% of the time, the air quality in the consulting room and CT room in the 222 nm ultraviolet group met the environment standards for airborne bacterial colony criteria of class Ⅰ or class Ⅱ.ConclusionThe upper-room 222 nm ultraviolet radiation germicidal disinfection can effectively reduce the total number of airborne bacterial colonies and improve the environment for emergency department, and the continuous using of it is helpful for keeping the air safe and clean.