Comparison of electric hand dryers and paper towels for hand hygiene: a critical review of the literature.

Numerous studies are published on the benefits of electric hand dryers vs paper towels (PT) for drying hands after washing. Data are conflicting and lacking key variables needed to assess infection risks. We provide a rapid scoping review on hand-drying methods relative to hygiene and health risks. Controlled vocabulary terms and keywords were used to search PubMed (1946-2018) and Embase (1947-2018). Multiple researchers independently screened abstracts for relevance using predetermined criteria and created a quality assessment scoring system for relative study comparisons. Of 293 papers, 23 were included in the final analysis. Five studies did not compare multiple methods; however, 2 generally favoured electric dryers (ED); 7 preferred PT; and 9 had mixed or statistically insignificant results (among these, 3 contained scenarios favourable to ED, 4 had results supporting PT, and the remaining studies had broadly conflicting results). Results were mixed among and within studies and many lacked consistent design or statistical analysis. The breadth of data does not favour one method as being more hygienic. However, some authors extended generalizable recommendations without sufficient scientific evidence. The use of tools in quantitative microbial risk assessment is suggested to evaluate health exposure potentials and risks relative to hand-drying methods. We found no data to support any human health claims associated with hand-drying methods. Inconclusive and conflicting results represent data gaps preventing the advancement of hand-drying policy or practice recommendations.

Improvement of quality attributes of sponge cake using infrared dried button mushroom.

Infrared-hot air method, when properly applied, can be used for achieving a high-quality product. The objective of this study was to determine the rheological properties of cake batters and physico-chemical, textural and sensory properties of sponge cake supplemented with four different levels (control, 5 %, 10 %, and 15 %) of button mushroom powder. The button mushroom slices were dried in an infrared-hot air dryer (250 W and 60 °C). The physical (volume, density, color) and chemical (moisture, protein, fat and ash) attributes were determined in the cakes. Increasing the level of substitution from 5 % to 15 % button mushroom powder significantly (p < 0.05) increased the protein and ash. The apparent viscosity in cake batter, and volume, springiness, and cohesiveness values of baked cakes increased with increasing button mushroom powder levels whereas the density, consistency, hardness, gumminess, chewiness and crumb L, b values of samples showed a reverse trend. Sensory evaluation results indicated that cake with 10 % button mushroom powder was rated the most acceptable.

Batch uniformity and energy efficiency improvements on a cabinet dryer suitable for smallholder farmers.

Drying can add value, facilitate transport and extend the storage life of agro-products; therefore, in developing countries with poorly established cool-chains, drying is particularly effective. Furthermore, drying within small-scale village-based enterprises contributes to rural development. However, most equipment suitable to such operations yields a product of non-uniform quality and shows low levels of energy efficiency. The aim of this research was to improve the batch uniformity and the energy efficiency of a cabinet dryer suitable for smallholder farmers. Experiments were carried out with the cooperation of a dryer manufacturer and a group of users. On each trial 144.5 kg of peeled and deseeded litchis were placed at the dryer's 17 trays, that were stacked atop each other. Moisture content (wet basis) was reduced from 87 to 23 % in about 15.5 h. It was found that a low-cost modification to the dryer chamber's air inlet was able to improve heat distribution and increase the uniformity of the fruit's moisture content. In the original design, at the end of the drying process, moisture content of the fruits on the top tray was 38 % while at the bottom tray was 12 %. The modification to the dryer reduced this disparity and the final moisture content of the fruits placed at the top tray was 25 % while at the bottom tray was 21 %. In addition, the modification reduced the dryer's air mass flow from 0.3 to 0.1 kg s(-1) without jeopardizing drying forces, consequently the dryer energy efficiency increased from 33 to 42 %.

Design and Experiment of Combined Infrared and Hot-Air Dryer Based on Temperature and Humidity Control with Sea Buckthorn (Hippophae rhamnoides L.).

A drying device based on infrared radiation heating technology combined with temperature and humidity process control technology was created to increase the drying effectiveness and quality of sea buckthorn. Based on the conventional k-turbulence model, the velocity field in the air distribution chamber was simulated using COMSOL 6.0 software. The airflow of the drying medium in the air distribution chamber was investigated, and the accuracy of the model was verified. Given that the inlet of each drying layer in the original model had a different velocity, the velocity flow field was improved by including a semi-cylindrical spoiler. The results showed that installation of the spoiler improved the homogeneity of the flow field for various air intakes, as the highest velocity deviation ratio dropped from 26.68% to 0.88%. We found that sea buckthorn dried more rapidly after being humidified, reducing the drying time by 7.18% and increasing the effective diffusion coefficient from 1.12 × 10-8 to 1.23 × 10-8 m2/s. The L*, rehydration ratio, and vitamin C retention rate were greater after drying with humidification. By presenting this hot-air drying model as a potential high-efficiency and high-quality preservation technology for sea buckthorn, we hope to advance the development of research in the sea buckthorn drying sector.

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.

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.

Modelling and Optimization of the Processing of a Healthy Snack Bar Made of Grape and Tomato Pomaces.

A snack made of 36% by byproducts of grape and tomato pomaces was developed, also including other ingredients, such as oats, chia, quinoa, honey and peanut butter. The recipe was defined as tasty and healthy by a focus group. The snack was produced by using forced air at three different drying temperatures (50 °C, 60 °C and 70 °C). The Newton, Page, Henderson and Pabis, and Midilli-Kucuk models fit the drying curves well. The average values for the Newton's model drying constants were k50 = 2.71 × 10-1 ± 3 × 10-3 min-1, k60 = 2.76 10-1 ± 4 × 10-3 min-1 and k70 = 3.91 × 10-1 ± 8 × 10-3 min-1 at 50 °C, 60 °C and 70 °C, respectively. The product's quality was assessed in terms of storage with respect to water activity and texture (hardness, springiness, cohesiveness, chewiness and resilience). There were no differences among the three tested processing temperatures in terms of their influence the final product's quality. As there were no significant differences between initial and final water activity and texture attributes at any temperature and they were mainly unaltered during storage, the snack bar was considered stable during this period. This new snack, which includes byproducts from the food industry, reduces food waste and contributes to a circular economic model, simultaneously presenting environmental and economic advantages.

Cutting Oxygen Production-Related Greenhouse Gas Emissions by Improved Compression Heat Management in a Cryogenic Air Separation Unit.

Oxygen production in cryogenic air separation units is related to a significant carbon footprint and its supply in the medicinal sphere became critical during the recent COVID-19 crisis. An improved unit design was proposed, utilizing a part of waste heat produced during air pre-cooling and intercooling via absorption coolers, to reduce power consumption. Variable ambient air humidity impact on compressed air dryers' regeneration was also considered. A steady-state process simulation of a model 500 t h-1 inlet cryogenic air separation unit was performed in Aspen Plus® V11. Comparison of a model without and with absorption coolers yielded an achievable reduction in power consumption for air compression and air dryer regeneration by 6 to 9% (23 to 33 GWh year-1) and a favorable simple payback period of 4 to 10 years, both depending on air pressure loss in additional heat exchangers to be installed. The resulting specific oxygen production decrease amounted to EUR 2-4.2 t-1. Emissions of major gaseous pollutants from power production were both calculated by an in-house developed thermal power plant model and adopted from literature. A power consumption cut was translated into the following annual greenhouse gas emission reduction: CO2 16 to 30 kilotons, CO 0.3 to 2.3 tons, SOx 4.7 to 187 tons and NOx 11 to 56 tons, depending on applied fossil fuel-based emission factors. Considering a more renewable energy sources-containing energy mix, annual greenhouse gas emissions decreased by 50 to over 80%, varying for individual pollutants.

Performance evaluation of heat pump dryer.

A batch type heat pump assisted dehumidified air dryer was developed successfully with a medium range of temperatures (30-41°C) for safe drying of heat sensitive crops. Dehumidification system of the developed heat pump dryer (HPD) maintained the relative humidity (RH) of air entering the drying chamber below 40%. The inlet drying air temperature decreased during early hours of drying followed by rapid rise between the 2nd and 10th h, after which the temperature was almost stable. The RH of inlet and exhaust drying air increased initially and decreased subsequently with drying time as product became drier. The HPD was found to have a specific moisture extraction rate between 0.55 and 1.10 kg/kWh. Energy consumption for HPD for 24 h of operation was found less (4.48-5.05 kWh) than the hot air dryer (5.65-9.6 kWh) while operating under different drying conditions. Better quality dried sweet pepper (Capsicum annuum L.) was obtained in HPD owing to lower drying air temperature.

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.