scholarly journals Public Buses Decontamination by Automated Hydrogen Peroxide Aerosolization System

2021 ◽  
Vol 9 (E) ◽  
pp. 847-856
Author(s):  
Attapol Arunwuttipong ◽  
Parinton Jangtawee ◽  
Viwat Vchirawongkwin ◽  
Wiyong Kangwansupamonkon ◽  
Kavin Asavanant ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Public Transportation ◽  
Biological Indicators ◽  
Biological Indicator ◽  
Transmission Risk ◽  
Geobacillus Stearothermophilus ◽  
Aerosol Generator ◽  
Comparison Results ◽  
Decomposition Time ◽  
Chemical Indicator

BACKGROUND: Public transportation has been linked to an increase in the risk of coronavirus disease 2019 transmission. The effective decontamination system using aerosolized hydrogen peroxide can mitigate the transmission risk from using public transportation. AIM: The aim of this study was to develop and validate an effective decontamination system for public transport. METHODS: The experimental research was performed in 13 inter-city public buses. The aerosol generator with ultrasonic atomizer was used in the experiment. The validation process for disinfection was conducted using both a chemical indicator (CI) and spore discs biological indicator (inoculated with 106 Geobacillus stearothermophilus enclosed in glassine envelopes). The CIs and biological indicators were marked by number and placed in nine locations on each bus. The decontamination cycle was developed by analyzed of various aerosolized and decomposition period. Both concentrations of hydrogen peroxide, 5% and 7%, were used for comparison. RESULTS: In an aerosolized period, both concentrations of hydrogen peroxide at 30 min were effective for sporicidal 6-log reductions. The decontamination cycle totaled 100 min, based on a 70 min average decomposition time. CONCLUSIONS: The automated hydrogen peroxide aerosolized system is a highly effective and safe method of decontaminating public buses.

Evaluation of a Rapid Readout Biological Indicator for Flash Sterilization with Three Biological Indicators and Three Chemical Indicators

1993 ◽  
Vol 14 (7) ◽  
pp. 390-394 ◽  
Author(s):  
William A. Rutala ◽  
Maria F. Gergen ◽  
David J. Weber
Keyword(s):  
Enzyme Activity ◽  
Bacillus Stearothermophilus ◽  
Color Change ◽  
Safety Margin ◽  
Biological Indicators ◽  
Biological Indicator ◽  
Processing Conditions ◽  
Fluorescent Product ◽  
Chemical Indicators ◽  
Chemical Indicator

AbstractObjective:Flash sterilization is most commonly used for emergency sterilization of unwrapped items in a gravity displacement sterilizer for three minutes. Sterilization quality assurance is monitored by biological indicators that require a 24-hour incubation prior to reading. In this study, we compared a new biological indicator that provides results within 60 minutes with three conventional, 24-hour biological indicators for monitoring flash sterilization and three chemical indicators.Design:Conventional biological indicators tested included the conventional Attest 1261, Proof Flash and Assert, while the rapid readout indicator tested was Attest 1291. Attest Rapid Readout detects the presence of aBacillus stearothermophilusenzyme by reading a fluorescent product that is produced by the enzymatic break-down of a nonfluorescent substrate. Chemical indicators tested included Comply, Incheque, and Thermalog S. Survival at 132°C in a gravity displacement sterilizer was measured by media color change after incubation for 24 hours at 56°C for the three conventional biological indicators, fluorescence at 60 minutes for the Attest Rapid Readout biological indicator, and color change for the chemical indicators. Each exposure time was replicated four times with 10 of each biological and chemical indicator per run.Results:The conventional biological indicators (Attest, Proof Flash, and Assert) had 90%, 48%, and 40% spore survival at two minutes exposure; 23%, 3%, and 0% at three minutes exposure; and 3%, 0%, and 0% at four minutes exposure respectively. The Attest Rapid Readout biological indicator had 88%, 33%, and 0% enzyme activity detectable at 2, 3, and 4 minutes exposure. The chemical indicators Comply, Incheque, and Thermalog S revealed sterilization failure rates of 100%, 100%, and 100% at 0 minutes exposure; 100%, 100%, and 45% at one minute; 0%, 0%, and 28% at two minutes exposure; 0%, 0%, and 18% at three minutes exposure; and 0%, 0%, and 0% at four minutes exposure, respectively.Conclusion:The sensitivity of the Attest Rapid Readout parallels the conventional biological indicators. These data suggest that a 60-minute rapid readout biological indicator is equivalent to the 24-hour biological indicators. If further studies demonstrate that a four-minute flash sterilization cycle provides a needed safety margin to ensure sterilization, then consideration should be given to requiring a four-minute flash sterilization cycle. Chemical indicators were too sensitive to the processing conditions (eg, steam) and are inadequate to ensure adequate sterilization.

Comparison of the Microbiological Efficacy of Hydrogen Peroxide Vapor and Ultraviolet Light Processes for Room Decontamination

2012 ◽  
Vol 33 (5) ◽  
pp. 507-512 ◽  
Author(s):  
Nancy L. Havill ◽  
Brent A. Moore ◽  
John M. Boyce
Keyword(s):  
Hydrogen Peroxide ◽  
Prospective Observational Study ◽  
Biological Indicators ◽  
Line Of Sight ◽  
Geobacillus Stearothermophilus ◽  
Log Reduction ◽  
Before And After ◽  
The Mean ◽  
Mean Cycle ◽  
Hydrogen Peroxide Vapor

Objective.To compare the microbiological efficacy of hydrogen peroxide vapor (HPV) and ultraviolet radiation (UVC) for room decontamination.Design.Prospective observational study.Setting.500-bed teaching hospital.Methods.HPV and UVC processes were performed in 15 patient rooms. Five high-touch sites were sampled before and after the processes and aerobic colony counts (ACCs) were determined. Carrier disks with ~106Clostridium difficile (CD) spores and biological indicators (BIs) with 104 and 106Geobacillus stearothermophilus spores were placed in 5 sites before decontamination. After decontamination, CD log reductions were determined and BIs were recorded as growth or no growth.Results.93% of ACC samples that had growth before HPV did not have growth after HPV, whereas 52% of sites that had growth before UVC did not have growth after UVC (P < .0001). The mean CD log reduction was >6 for HPV and ~2 for UVC. After HPV 100% of the 104 BIs did not grow, and 22% did not grow after UVC, with a range of 7%–53% for the 5 sites. For the 106 BIs, 99% did not grow after HPV and 0% did not grow after UVC. Sites out of direct line of sight were significantly more likely to show growth after UVC than after HPV. Mean cycle time was 153 (range, 140–177) min for HPV and 73 (range, 39–100) min for UVC (P < .0001).Conclusion.Both HPV and UVC reduce bacterial contamination, including spores, in patient rooms, but HPV is significantly more effective. UVC is significantly less effective for sites that are out of direct line of sight.

scholarly journals Validation of N95 filtering facepiece respirator decontamination methods available at a large university hospital

2020 ◽  
Author(s):  
Krista R. Wigginton ◽  
Peter J. Arts ◽  
Herek Clack ◽  
William J Fitzsimmons ◽  
Mirko Gamba ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Relative Humidity ◽  
Hepatitis Virus ◽  
Biological Indicators ◽  
Biological Indicator ◽  
Filtration Efficiency ◽  
Full Scale ◽  
Moist Heat ◽  
N95 Respirators ◽  
The Impact

AbstractImportanceFiltering facepiece respirators, including N95 masks, are a critical component of infection prevention in hospitals. Due to unprecedented shortages in N95 respirators, many healthcare systems have explored reprocessing of N95 respirators. Data supporting these approaches are lacking in real hospital settings. In particular, published studies have not yet reported an evaluation of multiple viruses, bacteria, and fungi along with respirator filtration and fit in a single, full-scale study.ObjectiveWe initiated a full-scale study to evaluate different N95 FFR decontamination strategies and their impact on respirator integrity and inactivating multiple microorganisms, with experimental conditions informed by the needs and constraints of the hospital.MethodsWe explored several reprocessing methods using new 3M™ 1860 N95 respirators, including dry (<10% relative humidity) and moist (62-66% relative humidity) heat (80-82 °C) in the drying cycle of industrial instrument washers, ethylene oxide (EtO), pulsed xenon UV (UV-PX), hydrogen peroxide gas plasma (HPGP), and vaporous hydrogen peroxide (VHP). Respirator samples were treated and analyzed for biological indicator inactivation using four viruses (MS2, phi6, influenza A virus, murine hepatitis virus), three bacteria (Escherichia coli, Staphylococcus aureus, Geobacillus stearothermophilus), and the fungus Aspergillus niger. The impact of different application media was also evaluated. In parallel, decontaminated respirators were evaluated for filtration integrity and fit.ResultsVHP resulted in >2 log10 inactivation of all tested biological indicators. The combination of UV-PX + moist heat resulted in >2 log10 inactivation of all biological indicators except G. stearothermohphilus. Greater than 95% filtration efficiency was maintained following 2 (UV-PX + <10% relative humidity heat) or 10 (VHP) cycles of treatment, and proper fit was also preserved. UV-PX + dry heat was insufficient to inactivate all biological indicators. Although very effective at virus decontamination, HPGP resulted in decreased filtration efficiency after 3 cycles, and EtO treatment raised potential toxicity concerns. The observed inactivation of viruses with UV-PX, heat, and hydrogen peroxide treatments varied as a function of which culture media (PBS buffer or DMEM) they were deposited in.Conclusions and RelevanceHigh levels of biological indicator inactivation were achieved following treatment with either moist heat or VHP. These same treatments did not significantly impact mask filtration or fit. Hospitals have a variety of scalable options to safely reprocess N95 masks. Beyond value in the current Covid-19 pandemic, the broad group of microorganisms and conditions tested make these results relevant in potential future pandemic scenarios.

Determination of Optimal Public Transportation Routes Using Firefly and Tabu Search Algorithms

2020 ◽  
Vol 4 (5) ◽  
pp. 884-891
Author(s):  
Salwa Salsabila Mansur ◽  
Sri Widowati ◽  
Mahmud Imrona
Keyword(s):  
Tabu Search ◽  
Public Transportation ◽  
Traffic Congestion ◽  
Search Algorithm ◽  
Urban Transportation ◽  
The Public ◽  
Comparison Results ◽  
Congestion Problems ◽  
Transportation Routes

Traffic congestion problems generally caused by the increasing use of private vehicles and public transportations. In order to overcome the situation, the optimization of public transportation’s route is required particularly the urban transportation. In this research, the performance analysis of Firefly and Tabu Search algorithm is conducted to optimize eleven public transportation’s routes in Bandung. This optimization aims to increase the dispersion of public transportation’s route by expanding the scope of route that are crossed by public transportation so that it can reach the entire Bandung city and increase the driver’s income by providing the passengers easier access to public transportations in order to get to their destinations. The optimal route is represented by the route with most roads and highest number of incomes. In this research, the comparison results between the reference route and the public transportation’s optimized route increasing the dispersion of public transportation’s route to 60,58% and increasing the driver’s income to 20,03%.

scholarly journals Virus Transmission Risk in Urban Rail Systems: Microscopic Simulation-Based Analysis of Spatio-Temporal Characteristics

2021 ◽  
pp. 036119812110101
Author(s):  
Jiali Zhou ◽  
Haris N. Koutsopoulos
Keyword(s):  
Public Transportation ◽  
Virus Transmission ◽  
Flow Characteristics ◽  
Transportation Systems ◽  
Transmission Risk ◽  
Microscopic Simulation ◽  
Spatial And Temporal Patterns ◽  
Subway System ◽  
Public Transportation Systems ◽  
The Impact

The transmission risk of airborne diseases in public transportation systems is a concern. This paper proposes a modified Wells-Riley model for risk analysis in public transportation systems to capture the passenger flow characteristics, including spatial and temporal patterns, in the number of boarding and alighting passengers, and in number of infectors. The model is used to assess overall risk as a function of origin–destination flows, actual operations, and factors such as mask-wearing and ventilation. The model is integrated with a microscopic simulation model of subway operations (SimMETRO). Using actual data from a subway system, a case study explores the impact of different factors on transmission risk, including mask-wearing, ventilation rates, infectiousness levels of disease, and carrier rates. In general, mask-wearing and ventilation are effective under various demand levels, infectiousness levels, and carrier rates. Mask-wearing is more effective in mitigating risks. Impacts from operations and service frequency are also evaluated, emphasizing the importance of maintaining reliable, frequent operations in lowering transmission risks. Risk spatial patterns are also explored, highlighting locations of higher risk.

A Head-to-Head Comparison of Hydrogen Peroxide Vapor and Aerosol Room Decontamination Systems

2011 ◽  
Vol 32 (9) ◽  
pp. 831-836 ◽  
Author(s):  
T. Holmdahl ◽  
P. Lanbeck ◽  
M. Wullt ◽  
M. H. Walder
Keyword(s):  
Hydrogen Peroxide ◽  
Cycle Time ◽  
New Technologies ◽  
Biological Indicators ◽  
The Other ◽  
Test Room ◽  
Cycle Times ◽  
Hydrogen Peroxide Vapor ◽  
In Vitro Comparison

Objective.New technologies have emerged in recent years for the disinfection of hospital rooms and equipment that may not be disinfected adequately using conventional methods. There are several hydrogen peroxide–based area decontamination technologies on the market, but no head-to-head studies have been performed.Design.We conducted a head-to-head in vitro comparison of a hydrogen peroxide vapor (HPV) system (Bioquell) and an aerosolized hydrogen peroxide (aHP) system (Sterinis).Setting.The tests were conducted in a purpose-built 136-m3test room.Methods.One HPV generator and 2 aHP machines were used, following recommendations of the manufacturers. Three repeated tests were performed for each system. The microbiological efficacy of the 2 systems was tested using 6-log Tyvek-pouchedGeobacillus stearo-thermophilusbiological indicators (BIs). The indicators were placed at 20 locations in the first test and 14 locations in the subsequent 2 tests for each system.Results.All BIs were inactivated for the 3 HPV tests, compared with only 10% in the first aHP test and 79% in the other 2 aHP tests. The peak hydrogen peroxide concentration was 338 ppm for HPV and 160 ppm for aHP. The total cycle time (including aeration) was 3 and 3.5 hours for the 3 HPV tests and the 3 aHP tests, respectively. Monitoring around the perimeter of the enclosure with a handheld sensor during tests of both systems did not identify leakage.Conclusion.One HPV generator was more effective than 2 aHP machines for the inactivation ofG. stearothermophilusBIs, and cycle times were faster for the HPV system.

Decision risk approach to the application of biological indicators in vapor phased hydrogen peroxide bio-decontamination

2018 ◽  
Vol 32 (4) ◽  
pp. e3015
Author(s):  
Éva Pusztai ◽  
Sándor Kemény ◽  
Emese Vágó ◽  
Anikó Horváth
Keyword(s):  
Hydrogen Peroxide ◽  
Biological Indicators ◽  
Risk Approach
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