Environmental contamination and airborne microbial counts: a role for hydroxyl radical disinfection units?

J Hosp Infect. 2011 Jul;78(3):194-9. doi: 10.1016/j.jhin.2011.03.003. Epub 2011 Apr 17.


Environmental contamination is thought to play a role in the spread of infection in hospitals and there has been increased interest in novel air disinfection systems in preventing infection. In this study the efficacy of a hydroxyl radical air disinfection system (Inov8 unit) in reducing the number of airborne bacteria was assessed in a clinical setting. Environmental contamination was assessed using settle plates and air samples in three settings: (1) non-clinical room; (2) non-clinical room with defined activity; and (3) single intensive care unit cubicle. A comparison of air counts and environmental contamination rates was made with the Inov8 units on and off. The Inov8 unit produced an overall reduction in both air sample and settle plate counts in each setting (P<0.001, Wilcoxon signed-rank test). There was a mean reduction in air sample counts of 26%, 39% and 55% for settings 1, 2 and 3 respectively. The corresponding reductions in settle plate counts were 35%, 62% and 54%. These results suggest that this type of novel air disinfection may have a role in improving air quality and reducing environmental contamination within clinical isolation rooms. Further work is required to assess the effect on specific pathogens, and to establish whether this will reduce the risks of patients and/or healthcare workers acquiring such pathogens from the environment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Air Microbiology*
  • Bacteria / drug effects*
  • Bacteria / isolation & purification*
  • Colony Count, Microbial
  • Cross Infection / prevention & control*
  • Disinfectants / pharmacology*
  • Disinfection / methods*
  • Humans
  • Hydroxyl Radical / pharmacology*


  • Disinfectants
  • Hydroxyl Radical