Objective To compare the air disinfection effects of different human-machine coexistence disinfection methods in the high-risk areas of airborne diseases in medical and healthcare institutions, and to provide a reference for the prevention and control of airborne diseases in medical and healthcare institutions.

Methods Field trials were conducted in the fever clinic, the infection disease department, and dental clinics of a tertiary hospital in Shanghai, respectively. The existing air disinfection methods (plasma air disinfection machine, circulating air ultraviolet disinfection machine or negative pressure ventilation system), upper-room 222 nm ultraviolet germicidal system, and the combination of the existing air disinfection methods and upper-room 222 nm ultraviolet germicidal system were all used in each location in the experiment group. The control group did not adopt specific air disinfection methods. Air sampling was conducted by the six-level sieve hole microbial sampler or the flat slab exposure method. The daily air sampling time was from 8:00 a.m. to 16:00 p.m., with one sample per hour, and a total of 9 samples were taken. The disinfection effects were compared by calculating the total number of airborne bacteria colonies and the sterilization rate for each disinfection method.

Results The total numbers of airborne bacteria colonies in the fever outpatient infusion room, the ward and nurse station of infection disease department of 222 nm group were lower than that in the control group (P=0.005,P<0.001,P<0.001). The total numbers of airborne bacteria colonies in the fever outpatient infusion room and the dental examination room of 222 nm group were lower than that in the control group or plasma air disinfection machine group (P=0.022,P=0.014). The total numbers of airborne bacteria colonies in the nucleic acid sampling room of plasma air disinfection machine group combined with 222 nm group were lower than that in plasma air disinfection machine group (P=0.019). The total numbers of airborne bacteria colonies in the CT examination room of fever clinic of the 222 nm group were lower than that in the circulating air ultraviolet disinfection machine group (P=0.002). The total numbers of airborne bacteria colonies in the CT examination room of 222 nm group combined with circulating air ultraviolet disinfection machine were lower than that of circulating air ultraviolet disinfection machine group and the control group (P=0.008,P<0.001). The air sterilization rate of upper-room 222 nm ultraviolet germicidal system ranged from 48.04% to 73.74%. The air sterilization rate of plasma air/circulating air ultraviolet disinfection machine combined with the upper-room 222 nm ultraviolet germicidal system ranged from 6.86% to 73.77%.

Conclusion Upper-room 222 nm ultraviolet germicidal system could effectively reduce airborne colonies in the air and improve air hygiene quality in both clinic and ward environments with high airborne transmission risks.