Assessment of potential for viral contamination of user and environment via aerosols generated during hand drying: A pilot study.

Background: Hand drying is an essential step of hand hygiene, helping remove microbes remaining on hands following handwashing. However, it is unclear whether particles dispersed or aerosolized during hand drying can also have an impact on microbe dissemination and so pose an infection risk. Methods: We used a PR772 bacteriophage to investigate whether microorganisms remaining on hands can disperse in the washroom environment and contaminate facemasks of others sharing the same space, as a surrogate for virus inhalation risk. Hand drying using either a jet air dryer or paper towels were performed, and mask contamination by splattering and droplet deposition was investigated, up to 15 min following each procedure. Results: Facemask contamination by splattering was 10-fold higher when a jet air dryer was used, compared with hand drying by paper towels, for both the person performing the hand drying and for standby users stationed at 1 and 2 m distance. Facemask contamination by droplet/aerosols deposition was higher in the first 5 min following hand drying, for both methods; however, virus load was significantly higher when a jet air dryer was used. In the jet air dryer assays, facemask contamination increased at 15 min post-hand drying, suggesting aerosolization of small particles that remain airborne for longer. Conclusion: When using a jet air dryer, virus contamination dispersed further and for a longer period of time (up to 15 min post hand-drying). The method chosen for hand drying can potentially impact the airborne dissemination of microbial pathogens, including respiratory virus, and so potentially increase the risk of exposure and infection for other washroom users.

Aerosols and Bacteria From Hand Washing and Drying in Indoor Air.

Effective hand drying is an important part of hand hygiene that can reduce the risk of infectious disease transmission through cross-contamination of surfaces by wet hands. However, hand drying methods may also cause aerosolisation of pathogenic microorganisms if they are present in washed hands. This study investigated experimentally the impact of washing hands and different hand drying methods on the concentration and size distribution of aerosols and bacteria in indoor air. In this experiment, aerosol and bacteria concentrations were measured in indoor air while volunteers rinsed their hands with water or washed with soap and water prior to drying them with paper towels or jet air dryers. Results showed that the concentration of aerosols and bacteria in air increased with people walking in the room and washing hands, with a further increase during the hand drying process. The concentration of aerosols decreased with particle size, with maximum concentrations after drying hands of 6.63 × 106 ± 6.49 × 105 and 2.28 × 104 ± 9.72 × 103 particles m-3 for sizes 0.3 to <0.5 and ≥5.0 µm, respectively. The concentration of bacteria in indoor air after drying hands increased to a maximum of 3.81 × 102 ± 1.48 × 102 CFU m-3 (jet air dryers) and 4.50 × 102 ± 4.35 × 101 CFU m-3 (paper towels). This study indicates that the increase of aerosols and bacteria in air after drying hands with jet air dryers or paper towels are comparable and not statistically different from concentrations associated with walking and washing hands in the same environment. This work can support the development of hand hygiene practices and guidelines for public washrooms.

The method used to dry washed hands affects the number and type of transient and residential bacteria remaining on the skin.

BACKGROUND: Widespread antibiotic resistance has led to fears that we are entering a post-antibiotic era and the relatively simple premise of hand washing to reduce transfer of bacteria and viruses has never been more important. Much of the emphasis has been on hand-washing technique, type of soap, and maintaining compliance but effective drying of the hands is just as important. AIM: To compare the efficacy of drying washed hands with a jet air dryer or paper towels to remove transient bacterial contamination and to determine the effect on residential flora. METHODS: Eighty volunteers were recruited. The entire surfaces of volunteers' hands were artificially contaminated with Escherichia coli before being washed and dried; then bacteria remaining on the skin were recovered and enumerated. In the second part of the study the number and types of bacteria comprising the natural flora remaining on washed and dried hands were determined. FINDINGS: Significantly fewer transient and residential bacteria remained on the skin if hands were dried with a jet air dryer (P < 0.001). Drying hands with paper towels increased the number of resident bacteria, including potentially pathogenic species, released from the volunteers' skin, compared to a jet air dryer. CONCLUSION: The number and types of bacteria remaining on washed hands were affected by the drying method. Hands dried with a jet air dryer harboured fewer viable bacteria, reducing the risk of infection transmission via touch. This could be especially important for healthcare workers who are constantly in contact with large numbers of vulnerable patients.