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 &lt;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.</p

Can air purification improve sleep quality? A 2-week randomised controlled crossover pilot study in healthy adults

Insufficient quantity and quality of sleep is a public health concern which can be addressed by interventions for improving sleep outcomes. Environmental factors such as poor air quality are a potential target for intervention, particularly in light of associations between air pollution and worse sleep. The aim of this pilot study was to investigate the effects of using an air purifier on sleep outcomes and mood in 30 healthy adults. There were two conditions (i) air purifier with a High Efficiency Particulate Air (HEPA) filter (ii) air purifier with a placebo filter. Participants undertook both conditions, each over two weeks with a two-week washout, following a counterbalanced, double-blind design. Daily sleep outcomes were measured with actigraphy watches and sleep diaries, whilst daily mood was assessed with the Positive and Negative Affect Schedule. The Insomnia Severity Index, the Pittsburgh Sleep Quality Index, and symptoms of anxiety and depression were measured pre and post. The purifier filter was associated with increased total sleep time for an average of 12 minutes per night and increased total time in bed for an average of 19 minutes per night relative to the placebo. There were several sleep and mood outcomes for which no changes were observed, and time awake after sleep onset was higher for the purifier filter. Air quality was better during the HEPA filter condition. These findings offer positive indications that environmental interventions which improve air quality can have benefits for sleep outcomes in healthy populations who are not exhibiting clinical sleep disturbances

The influence of hydrogen bubble formation on the removal of Pseudomonas fluorescens biofilms from platinum electrode surfaces

Hydrogen bubble formation on the surface of platinum electrodes as a means of removing biofilms was studied. Biofilms of Pseudomonas fluorescens of different ages were grown on platinum electrodes and challenged with hydrogen bubbles formed at the surface of the electrodes, by cycling the potential at ?2.0 V. The removal of the biofilms from the surfaces was assessed by direct epifluorescence microscopy. The removal of the biofilm from the surface was dependent on the biofilm age. As the biofilm became older, the duration of bubble formation needed to achieve complete removal changed, but in some cases, it was not possible to obtain a completely clean surface. An enhancement of biofilm removal was obtained if the potential was cycled between ?0.5 and 1.0 V for 30 min prior to bubble generation, probably due to the weakness of the forces established between the surface and the biofilm and within the biofilm.<br/