Moura et al.
10.3389/fpubh.2025.1664322
hand dryer. Volunteers wore a new N95 respirator for each 5-min period tested: at 10–15 and at 25–30 min post-hand drying. The purpose was to assess if each hand drying method created aerosols that could deposit on the masks surface when subjected to the air displacement associated with regular breathing. Hand drying using AW+D wall hand dryer and A9KJ hand dryer resulted in mask contamination by aerosols at both positions and at all timepoints, whereas this was observed in only 60% of the testing points when PT were used. At the 15-min timepoint, bacteriophage aerosolization at the hand drying station position was 10-fold lower with PT than with the AW+D wall hand dryer, and 100-fold lower compared to the A9KJ hand dryer (Figure 3). Contamination of facemasks at the hand dryer position was highest at all time points investigated when the A9KJ hand dryer was used. However, at the standby position, facemask contamination was generically higher when AW+D wall hand dryer was used, with exception of the 15 min timepoint, where A9KJ hand dryer resulted in a non-significantly higher mask contamination compared with the AW+D wall hand dryer (Figure 3). For all methods there was a slight increase on mask contamination observed at 30 min compared to 15 min.
individuals’ hands and their potential for contamination of the washroom environment (1, 18, 19, 28, 29). Those observations are likely impacted by the different experimental designs, with a hand washing step of 20s following WHO guidelines (25) and/or hand drying performed until all moisture has been removed, often featuring in experiments where electric hand dryers performed best. However, in real-life settings, poor hand wash practices (no soap, less than 20s) and hand drying for short periods are common (29–32). One study comparing different hand drying methods found that 68% of their volunteers used a jet air dryer for up to 10s in their daily life, whereas experiments employed an average time of >27s to achieve full hand dryness (29). This is relevant as residual moisture in hands can increase microorganism transfer from hands to surfaces (1, 27). We looked to investigate the efficacy of new electric hand drying systems, the Dyson AW+D wall hand dryer and the A9KJ hand dryer, in removing contamination from hands and their potential to cause particle aerosolization for an extended period, compared with PT. PT resulted in significantly lower splattering contamination of all surfaces, which was associated with lower transfer of microbial contamination to the door handle via direct contact, similar to previous reports (1). Droplet dispersion of both the food dye and bacteriophage assays showed A9KJ hand dryer was associated with a higher contamination of walls and floor, whereas person contamination was higher when using the Dyson AW+D wall hand dryer. Both hand dryers have a 2-arm design and similar air-drying velocity; however, the 30 ° hand drying angle in A9KJ appears to displace more air toward the adjacent surfaces (wall and floor), whereas the horizontal movement of hands during AW+D use suggests more air is displaced towards the nearby individuals.
Discussion
Hand drying is an integral step of hand hygiene (25, 26) and is essential in minimizing the risk of pathogen spread (1, 20, 21, 27). Previous studies reported different results regarding the efficacy of electric hand dryers in removing microbial contamination from
FIGURE 3 Mean qPCR bacteriophage levels and standard deviation recovered from N95 masks following hand drying. Bacteriophage deposition was investigated at 0 min, 15 min and 30 min post-hand drying, both at the hand drying station and at 1 m distance. Facemasks represented the risk for virus inhalation. * p < 0.05 significant differences between PT and Dyson AW+D wall hand dryer, and between PT and 9KJ, using a two-tail Mann–Whitney U test. # p < 0.05 significant differences between Dyson AW+D wall hand dryer and A9KJ hand dryer using a two-tail Mann–Whitney U test.
Frontiers in Public Health
06
frontiersin.org
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