Abstract: OBJECTIVE To evaluate the effectiveness and safety of 222 nm far-ultraviolet in control of health care-associated infections (HAIs) in ICUs. METHODS The single-room patients of general ICUs and emergency ICUs who were treated in The First Affiliated Hospital of Nanjing Medical University from Jul. 2024 to Sep. 2025 were recruited as the research subjects. Totally 125 patients who were hospitalized in 4 wards that were installed with 222 nm far-ultraviolet were assigned as the study group, and 662 patients who were hospitalized in the wards that were not installed with the device were chosen as the control group. The case-time infection rates, infection sites, pathogenic bacterial spectrums and instrument-associated infections were observed and compared between the two groups. The adverse reactions in the patients and health care workers were monitored. RESULTS The case-time infection rate of the study group was 5.60%(7 case-times), lower than 9.67%(64 case-times) of the control group; the thousand-day infection rate of the study group was 4.00‰, lower than 7.04‰ of the control group, however, there were no between-group differences. The patients with pulmonary infections (4 cases) and the patients with bloodstream infections (3 cases) were dominant in the study group; there were no cases of central line associated bloodstream infection (CLABSI) or catheter-associated urinary tract infection (CAUTI); the incidence rate of ventilator-associated pneumonia (VAP) was 2.09‰. The infection cases distributed broader in the control group, the incidence rates of VAP, CLABSI and CAUTI were 1.13‰, 0.91‰ and 0.33‰, respectively; there were also skin/incision infections, abdominal infections, intracranial infections, urinary tract infections and gastrointestinal tract infections. Totally 7 species of pathogens were isolated from the study group, 26 species from the control group, with the species more diversified. No adverse reactions were observed in the skin and eyes of the patients during the study. CONCLUSION The 222 nm far-ultraviolet has inhibitory effect on some of the pathogens from the ICU environment and shows potential positive significance in reducing the environmentally acquired infections, with the short-term safety favorable.