Bioluminescence-based hygiene evaluation of public washroom environment: Repeated measurement of post-handwashing facilities on baseline and before and after cleaning schedule.

Cheung, Matthew Man Fai; Suen, Lorna Kwai Ping; Au, Jessie Kit Ling; Lam, Simon Ching

BACKGROUND The risk of hand recontamination is often neglected after using hand washing facilities, which can increase the spread of pathogens. The study aimed to evaluate the hygienic condition of post-handwashing facilities in public washrooms at different timeslots, particularly those near food courts and restaurants located in shopping malls. METHODS This observational study was conducted in 12 public washrooms that ranged from low-end, middle-end, to high-end category on three different timeslots including baseline, T1 (immediate post-cleaning) and T2 (one-hour post-cleaning, with counting the footfall). Hand-touch surfaces with a high risk of recontamination after handwashing, which included paper tower dispensers, air drying outlets, and exit door handles, were evaluated by the surface adenosine triphosphate (ATP) bioluminescence method (ATP-value). ATP-values <500 relative light units (RLUs) were considered a good hygiene. Cleaning schedules and footfalls of each sampled washroom were obtained by direct observations. RESULTS The overall mean ATP value of washroom was 785 RLU (N = 108); the ATP values of female and male washrooms at T2 were 203 and 3,718 RLUs, respectively. The highest ATP value was found on the exit door handles of male washrooms (range=13 to 26,695 RLUs, mean=3,229 RLU). Regarding passed/failed hygiene conditions, there were significant differences in the proportion of exit door handles between genders (p=0.018) and timeslots (p=0.007) as well as that of paper towel button/screw between timeslots (p=0.025). CONCLUSION Attention should be paid at the exit door handles of male washrooms, where are high risks of cross and re-contamination.