Effects of hand disinfection with alcohol hand rub, ozonized water, or soap and water:

Hand hygiene is one of the simplest and most important defences against the spread of infection in healthcare settings, where hands routinely carry transient bacteria such as Escherichia coli (E. coli) between patients and surfaces. Alcohol-based hand rub has long been the global standard for hand disinfection, but frequent use is known to dry and irritate the skin, and skin irritation is a common reason staff give for skipping or shortening hand hygiene steps. A Norwegian research team set out to test whether ozonated water - water infused with ozone gas - could remove bacteria from hands as effectively as alcohol, while being gentler on the skin.

Background

Reducing the transfer of microbes on hands is central to infection prevention, yet the disinfectant most widely recommended for this job, alcohol hand rub, is also one of the most likely to cause dryness and irritation with repeated use. Poor tolerability can discourage consistent hand hygiene, so researchers have been looking for alternatives that disinfect effectively without damaging the skin barrier. Ozonated water had shown promise in smaller studies and was tested here directly against alcohol hand rub and conventional soap-and-water washing.

Study design

The study followed a modified version of the European Standard EN 1500:2013, the reference protocol used to test hygienic hand rubs. Fifty-five participants took part, most of them nursing students. Forty of them completed a crossover comparison, testing both alcohol hand rub and ozonated water on separate occasions, while a further 20 participants were assessed using soap and water. Before each test, hands were artificially contaminated with E. coli, then washed or disinfected using the assigned method. Researchers then rinsed the hands and measured the surviving bacteria, expressed as colony-forming units per millilitre (CFU/mL), to quantify how much contamination each method removed.

Findings

Baseline contamination was consistently high before disinfection, with 52 of the 55 participants starting at 30,000 CFU/mL or more. After disinfection, soap and water removed the most bacteria (median 50 CFU/mL), followed by ozonated water (median 250 CFU/mL), with alcohol hand rub performing least effectively of the three in this comparison (median 300 CFU/mL). Around two-thirds of participants said they preferred ozonated water over the other methods, and it produced no adverse skin effects during testing.

What the authors concluded

The authors concluded that ozonated water removed transient E. coli from artificially contaminated hands at least as well as alcohol hand rub, and that it may be a viable, better-tolerated alternative for hand disinfection alongside routine soap-and-water washing. They suggested that the flow rate of water used during washing may be as important as the choice of disinfectant itself. They called for larger studies in real clinical settings to confirm ozonated water's efficacy, and noted that its potential effect against viruses - including the then-emerging COVID-19 - warranted further investigation.

Limitations of this study

The sample was small and drawn largely from nursing students, who may not represent the wider healthcare workforce or general public. The soap-and-water group was not part of the crossover design and was tested in a separate cohort of 20 rather than the same 40 participants who tried alcohol and ozone, which limits direct comparability between all three methods. The model used artificial E. coli contamination rather than naturally occurring transient flora, and the study did not test effectiveness against viruses, a question the authors themselves flagged as needing further research. As the authors noted, larger studies conducted in real clinical settings are still required before firm conclusions can be drawn about ozonated water's place in routine hand hygiene practice.