Pre-task planning for construction worker safety and health: Implementation and assessment.

BACKGROUND: Compared to other industry sectors, construction workers experience a disproportionately high rate of occupational injuries and fatalities. As research findings suggest, most of these incidents could be prevented if hazards were proactively recognized and properly addressed. In the construction industry, pre-task planning (PTP) is a preventive process intended to describe each step of work, identify associated safety and health hazards, and recommend controls to eliminate or mitigate the hazards before work begins. Despite its importance, the construction industry lacks comprehensive guidelines to design and implement PTP in a consistent and effective manner. To fill this gap, this study pursued two objectives: (1) identify shortcomings in current PTP practices and explore recommended solutions from practitioners' perspectives and (2) translate research findings into an applied tool to help practitioners assess and improve the quality of their PTP process. METHODS: To fill the gap, 28 construction safety and health professionals and 104 workers were interviewed, and seven onsite PTP sessions were directly observed. RESULTS: Shortcomings of current PTP practices as well as recommended solutions were categorized as (1) planning and implementation, (2) all-trades coordination, (3) engagement and buy-in, (4) training and logistics, (5) workforce diversity and the language barrier, and (6) PTP content accessibility. DISCUSSION/CONCLUSIONS: An effective PTP process should be based on workers' direct involvement and input on task requirements and hazards. It needs to be regularly updated to reflect the changing work conditions. In addition to task-related information, to increase workers' awareness, PTP should paint a holistic view of the project and other trades' scopes.

Processing complementary foods to reduce mycotoxins in a medium scale Tanzanian mill: A hazard analysis critical control point (HACCP) approach.

Designing and implementing processing procedures for producing safe complementary foods in dynamic and unregulated food systems where common food staples are frequently contaminated with mycotoxins is challenging. This paper presents lessons about minimizing aflatoxins (AF) in groundnut flour and AF and/or fumonisins (FUM) in maize and groundnut pre-blended flour for complementary feeding in the context of a dietary research intervention in rural Tanzania. The flours were processed in collaboration with Halisi Products Limited (Halisi), a medium scale enterprise with experience in milling cereal-based flours in Arusha, Tanzania. Using a hazard analysis critical control point (HACCP) approach for quality assurance, two critical control points (CCPs) for AF in processing the pre-blended flour were identified: 1) screening maize before procurement, and 2) blending during the processing of each constituent flour. Blending of maize flour was also identified as a CCP for FUM. Visual inspection during screening and sorting were identified as important control measures for reducing AF, but these steps did not meet the criteria for a CCP due to lack of objective measurement and verifiable standards for AF. The HACCP approach enabled the production of low AF (<5 µg/kg) and FUM (<2 µg/g) flours with low rejection rates for the final products. The paper presents practical lessons that could be of value to a range of commercial processors in similar low- and middle-income contexts who are keen on improving food quality.

Evaluating the disaster preparedness of emergency medical services (EMS) facilities: a cross-sectional investigation in Iran.

INTRODUCTION: The preparedness of Emergency Medical Services (EMS) plays a crucial role in managing health disaster risks. This study was conducted to assess the disaster preparedness of EMS facilities in Iran, using a nationally reliable tool. METHODS: A cross-sectional study was conducted in May 2021 to evaluate the disaster preparedness of EMS facilities in Iran using a national standard tool. The census sampling approach was utilized to select the samples, and descriptive statistics, as well as analytical statistics like the independent t-test and Pearson's correlation test, were used to analyze the data using SPSS-18 software. RESULTS: The findings of this study revealed that the majority of EMS facilities in Iran possess a moderate level of preparedness in dealing with disasters. Also, the results indicate that EMS facilities have an average level of preparedness against disasters in all dimensions except for "coordination and cooperation" and "surge capacity". CONCLUSION: According to this study, the majority of EMS facilities in Iran are exposed to different disasters. Furthermore, the findings indicate that while EMS facilities are generally prepared to respond to disasters at an average level, there are some important preparedness gaps in dimensions like response capacities, coordination, and cooperation. Thus, specific strategies, standards, and procedures must be developed and disseminated by the National Medical Emergency Organization.

[Optimizing the use-by date of reusable medical devices. Experience in a healthcare establishment]. / Optimisation de la date limite d'utilisation des dispositifs médicaux réutilisables. Expérience dans un établissement de santé.

OBJECTIVES: Sterilized reusable medical devices have a use-by date, after which sterility is no longer guaranteed. There is currently no consensus on how this should be determined. The aim is to re-evaluate the expiry date of reusable medical devices, by means of a risk analysis and an assessment of the maintenance of the sterile state of reusable medical devices over time. METHODS: The risk analysis focused on the stages whose malfunction could compromise the sterility of reusable medical devices over time: packaging, transport and storage. Risk mapping was carried out in accordance with the methodology recommended by the French Health Authority. Based on standard NF EN ISO 11737, the assessment of the maintenance of the sterile state was checked on reusable medical devices after two, four and six months storage and on reusable medical devices that had expired more than a year previously. RESULTS: The risk analysis identified four failures and sixty-eight potential causes. The most sensitive stage was storage, which accounted for most of the critical and major causes. Improvement actions were proposed, such as the definition of a container maintenance plan. At the same time, 256 reusable medical devices were tested. The cultures remained sterile for all the containers, for folded products tested at 6 months and more and for the sachets tested at 2 and 4 months and at more than one year of storage. CONCLUSIONS: The DLU has been extended to 4 months for sachets, 6 months for folded products and maintained at six months for containers.

Determination of Cyanide and Cyanoglycosides in Sweetened Bean Paste by HPLC with Fluorescence Detection.

It is necessary to evaluate the efficiency of reduction for cyanide and cyanoglycosides during the manufacturing process from raw material beans to sweetened bean paste in a food hygiene control system from the viewpoint of food safety. Analytical methods for cyanide and cyanoglycoside determination in sweetened bean paste by HPLC with fluorescence detection were developed. In analysis of collection time of free cyanide in the free cyanide assay, the recovery was improved by extending the collection time, the recovery rate was >80% by 2 h. The accuracy, repeatability and intra-laboratory precision of the free cyanide assay were 82.3, 2.0, and 2.4%, respectively. The method for cyanoglycoside analysis was evaluated by 5 repeated spiked recovery experiments at a concentration of 10 ppm. The accuracy, repeatability and intra-laboratory precision of the cyanoglycoside method were 82.2, 1.9, and 3.4%, respectively. These analytical methods will enable the analysis of cyanide and cyanoglycosides in sweetened bean paste without using steam distillation method in the pretreatment.

Prevalence and antimicrobial resistance of Escherichia coli and Salmonella spp. in animal feed in Colombia.

Objective: To determine the prevalence and antimicrobial resistance of Escherichia coli and Salmonella spp. in animal feed samples collected between 2018 and 2021 in Colombia. Methods: This was a laboratory-based cross-sectional study using routine data from the program for inspection, surveillance, and control of animal feed at the Colombian Agriculture Institute. Samples of animal feed for swine, poultry, canine, feline, leporine, piscine, and equine species were processed for detection of E. coli and Salmonella spp. using enrichment and selective culture methods. Isolates were tested for antimicrobial susceptibility using an automated microdilution method. Results: Of 1 748 animal feed samples analyzed, 83 (4.7%) were positive for E. coli and 66 (3.8%) for Salmonella spp. The presence of E. coli and Salmonella spp. was highest in feed for poultry (6.4% and 5.5%) and swine (6.1% and 4.3%). Antimicrobial resistance testing was performed in 27 (33%) E. coli isolates and 26 (39%) Salmonella isolates. Among E. coli, resistance was most frequently observed to ampicillin (44.5%) followed by cefazolin (33.3%), ciprofloxacin (29.6%), ampicillin/sulbactam (26%), and ceftriaxone (11.1%). The highest resistance levels in Salmonella spp. isolates were against cefazolin (7.7%) and piperacillin/tazobactam (7.7%). Conclusions: This is the first study from Colombia reporting on the prevalence and antimicrobial resistance of E. coli and Salmonella spp. in animal feed samples. Its results establish a baseline over a wide geographical distribution in Colombia. It highlights the need to integrate antimicrobial resistance surveillance in animal feed due to the emergence of resistant bacteria in this important stage of the supply chain.

Development of a Knowledge Graph for Automatic Job Hazard Analysis: The Schema.

In the current practice, an essential element of safety management systems, Job Hazard Analysis (JHA), is performed manually, relying on the safety personnel's experiential knowledge and observations. This research was conducted to create a new ontology that comprehensively represents the JHA knowledge domain, including the implicit knowledge. Specifically, 115 actual JHA documents and interviews with 18 JHA domain experts were analyzed and used as the source of knowledge for creating a new JHA knowledge base, namely the Job Hazard Analysis Knowledge Graph (JHAKG). To ensure the quality of the developed ontology, a systematic approach to ontology development called METHONTOLOGY was used in this process. The case study performed for validation purposes demonstrates that a JHAKG can operate as a knowledge base that answers queries regarding hazards, external factors, level of risks, and appropriate control measures to mitigate risks. As the JHAKG is a database of knowledge representing a large number of actual JHA cases previously developed and also implicit knowledge that has not been formalized in any explicit forms yet, the quality of JHA documents produced from queries to the database is expectedly higher than the ones produced by an individual safety manager in terms of completeness and comprehensiveness.

Exposure levels for carbon monoxide in nuclear submarine atmosphere.

This work proposes exposure limits for carbon monoxide in the nuclear submarine environment. Linear and non-linear forms of the Coburn-Foster-Kane equation were used to evaluate carbon monoxide exposure for an environment with low oxygen content, different exposure times and crew physical activity levels. We evaluated the 90-day Continuous Exposure Guidance Level, 24-h and 1-h Emergency Exposure Guidance Levels and 10-day and 24-h Submarine Escape Action Levels. The results showed that the concentration of carbon monoxide in the environment must not exceed 9 ppm for the 90-day Continuous Exposure Guidance Level, 35 ppm for the 24-h Emergency Exposure Guidance Level, 90 ppm 1-h Emergency Exposure Guidance Level, 60 ppm for the 10-day Submarine Escape Action Level and 80 ppm for the 24-h Submarine Escape Action Level. Comparing these values with those established by the National Research Council for the United States Navy, the limits proposed by this work are verified to be lower, which may indicate a risk to the health of the crew. They also show the impact of the crew's level of physical activity on the formation of carboxyhemoglobin.

Decline in Traffic Congestion Increased Crash Severity in the Wake of COVID-19.

Highway fatalities are a leading cause of death in the U.S. and other industrialized countries. Using highly detailed crash, speed, and flow data, we show highway travel and motor vehicle crashes fell substantially in California during the response to the COVID-19 pandemic. However, we also show the frequency of severe crashes increased owing to lower traffic congestion and higher highway speeds. This "speed effect" is largest in counties with high pre-existing levels of congestion, and we show it partially or completely offsets the "VMT effect" of reduced vehicle miles traveled on total fatalities. During the first eleven weeks of the COVID-19 response, highway driving decreased by approximately 22% and total crashes decreased by 49%. While average speeds increased by a modest 2 to 3 mph across the state, they increased between 10 and 15 mph in several counties. The proportion of severe crashes increased nearly 5 percentage points, or 25%. While fatalities decreased initially following restrictions, increased speeds mitigated the effect of lower vehicle miles traveled on fatalities, yielding little to no reduction in fatalities later in the COVID period.

Evaluating the Use of Multisite Probabilistic Seismic Hazard Analysis: A Case of Sarpol-e Zahab City, Iran.

This paper evaluates the use of multisite (MS) probabilistic seismic hazard analysis (PSHA), which estimates the annual exceedance rate of a given level of ground motion in at least one of several sites as one of several possible results. For this purpose, (1) MS-PSHA is implemented through the Monte Carlo approach, taking into account various area sizes and correlation distances (CDs), and then (2) two proposals are represented as applications of MS-PSHA outcomes, both with reference to Sarpol-e Zahab City, a seismically active region located in the west of Iran. The first proposal attempts to determine the current code design probability of exceedance in at least one site, and the second one defines collapse prevention levels based on different probabilities of exceedance in at least one site. The efficiency of the results is discussed mainly by comparing them to recorded peak ground accelerations (PGAs) of three earthquakes, including the 2017 Sarpol-e Zahab 7.3 M w event that largely exceeded the code design spectrum. MS-PSHA results demonstrate reasonable performance both in determining design ground motions and evaluating current design code when the exact seismic parameters of the study area are used in the analysis. Moreover, developed code-type design spectra based on MS-PSHA provided safety against collapse compared to a recently occurring low-probability event. MS estimates for various CDs and probabilities of exceedance in at least one site can also provide flexible design strategies regarding the importance of a structure and expected damage on a regional scale.

[Risk mapping associated with organization of a COVID-19 immunization campaign]. / Cartographie des risques liés à l'organisation de la campagne de vaccination contre la COVID-19.

OBJECTIVES: COVID-19 caused more than 260,000 hospitalizations and nearly 64,000 deaths in France in 2020. Vaccination has become the best hope for gaining control of the pandemic. Our objective is to map the major risks associated with organization of the start of a COVID-19 immunization campaign in the Provence-Alpes-Côte d'Azur region, from December 2020 to April 2021 (inclusive). MATERIALS AND METHODS: The process associated with organization of a COVID-19 immunization campaign was described. Risks, causes, consequences and control elements were identified by 14 semi-structured interviews, involving 19 professionals involved in the important stages in the process. The analysis was performed using the process approach and by a Failure Mode, Effects and Criticality Analysis (FMECA). RESULTS: The process is divided into two approaches, one collective and one individual. Forty-seven risks have been identified and 15 actions proposed. Regional supply logistics chain, vaccination sites, appointment management and the Vaccine-COVID information system are the critical points. Overwork is the most common risk, which has been experienced by the study participants (n=18). It favours the disaffection of the health professionals, which is the major threat of this organization. Eligibility, medical consultation, and the post-vaccination period are under control. CONCLUSIONS: Principal risks associated with organization of a COVID-19 immunization campaign have been identified and action plans have been proposed to optimize current and future practices. It gives a regional vision, to be compared with other regional, national, and international data.

[Construction status and development strategy of GAP bases for Chinese herbal medicine].

Good agricultural practices(GAP) for Chinese herbal medicine(CHM) is the source of quality control in the production of CHM. To ensure the safety, efficacy, and quality of Chinese herbal and natural medicine, the international community has been exploring the implementation of GAP for CHM. The implementation of GAP for CHM has a far-reaching impact, and the scale planting of CHM has been expanding. However, the medicinal materials produced by the GAP bases for CHM still cannot fully meet the market demand, and the output and quality of CHM remain to be improved. This paper summarizes construction status of GAP bases for CHM.The 129 companies that passed the certification during the implementation of GAP for CHM included 196 GAP bases, forming the scale CHM production zone with Sichuan province, Yunnan province, Jilin province, Henan province, and Shandong province as the core.The total area of GAP bases for CHM in China is about 250 000-500 000 Mu(1 Mu≈667 m2), which is still less than 1% of the total production area of CHM. The international agricultural production quality management strategies are all market-oriented behaviors.Drawing on the international good agricultural and collection practice(GACP) and hazard analysis critical control point(HACCP) as well as the relevant policies of Chinese quality management of CHM, we put forward feasible suggestions for the further implementation of GAP for CHM:(1)The market rules and international experience should be followed and employed to promote GAP management of CHM and third-party implementation of GAP certification;(2)The sound development of GAP for CHM should be boosted with the HACCP management system and the revision of GAP for CHM;(3)The implementation of policies and standards should be stepped up to facilitate the building of a whole-course traceability system for the production of CHM with high quality and reasonable prices.

Assessing the Performance of Food Safety Management System Using Food Safety Management System Diagnostic Tools and Microbial Assessment Scheme: A Case of Powdered Beverage Manufacturers.

BACKGROUND: The objective of the study is to assess the performance of the Food Safety Management System (FSMS) among powdered beverage manufacturers using Food Safety Management System Diagnostic Tools (FSMS-DI) and Microbial Assessment Scheme (MAS). METHODS: FSMS-DI was used to evaluate the context factors, core control and core assurance activities of five powdered beverage manufacturers with different types of FSMS certification. Manufacturer A is not certified with any FSMS, while manufacturers B, C, D and E are complied with MeSTI, GMP, HACCP and ISO 22000, respectively. For MAS, samples were collected from the selected critical sampling locations of two manufacturers who complied FSMS with the least (manufacturer B) and the most stringent (manufacturer E) requirements. The samples consisted of two different types of powdered beverage products were analysed for total plate count (TPC), Salmonella, Escherichia coli, Staphylococcus aureus, yeast and mould count (YMC). Results: The food safety (FS) output of powdered beverages for manufacturer E was better (overall score of 3) than manufacturer B (overall score of 2-3). Manufacturer E was able to achieve their FS objectives. The FSMS activities of manufacturer C, D and E were better (overall score of 2-3) than manufacturer A and B (overall score of 1-2). CONCLUSION: The study demonstrated that FSMS-DI and MAS can be used to differentiate the FSMS performance of powdered beverage manufacturers with different types of FSMS certification. Higher scores of FSMS activities obtained by the manufacturer who complied with stringent FSMS certifications contributed to better microbiological safety performance of powdered beverages.

N-terminal acetylation mutants affect alpha-synuclein stability, protein levels and neuronal toxicity.

Alpha-synuclein (aSyn) protein levels are sufficient to drive Parkinson's disease (PD) and other synucleinopathies. Despite the biomedical/therapeutic potential of aSyn protein regulation, little is known about mechanisms that limit/control aSyn levels. Here, we investigate the role of a post-translational modification, N-terminal acetylation, in aSyn neurotoxicity. N-terminal acetylation occurs in all aSyn molecules and has been proposed to determine its lipid binding and aggregation capacities; however, its effect in aSyn stability/neurotoxicity has not been evaluated. We generated N-terminal mutants that alter or block physiological aSyn N-terminal acetylation in wild-type or pathological mutant E46K aSyn versions and confirmed N-terminal acetylation status by mass spectrometry. By optical pulse-labeling in living primary neurons we documented a reduced half-life and accumulation of aSyn N-terminal mutants. To analyze the effect of N-terminal acetylation mutants in neuronal toxicity we took advantage of a neuronal model where aSyn toxicity was scored by longitudinal survival analysis. Salient features of aSyn neurotoxicity were previously investigated with this approach. aSyn-dependent neuronal death was recapitulated either by higher aSyn protein levels in the case of WT aSyn, or by the combined effect of protein levels and enhanced neurotoxicity conveyed by the E46K mutation. aSyn N-terminal mutations decreased E46K aSyn-dependent neuronal death both by reducing protein levels and, importantly, by reducing the intrinsic E46K aSyn toxicity, being the D2P mutant the least toxic. Together, our results illustrate that the N-terminus determines, most likely through its acetylation, aSyn protein levels and toxicity, identifying this modification as a potential therapeutic target.

[Application of traditional Chinese medicine(TCM) traceability system based on TCM quality characteristics and HACCP system].

It is crucial to establish a complete set of traditional Chinese medicine(TCM) quality traceability management process system, in order to stabilize the pricing order of TCM market and reconstruct the transmission path of TCM quality signals. In this study, we reviewed the mature experience of food and drug supervision at home and abroad, analyzed the quality characteristics of TCM, and put forward that the quality control of TCM products can learn from the hazard analysis and critical control point(HACCP) system in food safety quality control. This study points out that the HACCP system provides not only technical guidance for the traceability management of TCM, but also ideas for improving the quality of TCM products and the safety risk control of TCM. The application of the HACCP system in TCM quality control can help establish an international dialogue platform for TCM and help realize the modernization and internationalization of TCM industry.

A new method for investigating the relationship between diet and mortality: hazard analysis using dietary isotopes.

Background: The population of Roman Britain are renowned for having elevated nitrogen (δ15) stable isotope values, which have been interpreted as evidence for the increased consumption of marine products. However, such results are now understood to also reflect episodes of stress and disease, suggesting that new interpretations are warranted.Aim: To test a novel approach which combines hazard mortality analysis and stable isotope data to determine whether there is a relationship between age-at-death, elevated δ15N values and mortality risk.Subjects and methods: This study used published osteological and dietary stable isotope data for nitrogen (δ15N) and carbon (δ13C) of 659 1st-5th century AD individuals aged >12 years old excavated from Roman cemeteries in Britain. The relationship between diet and mortality risk was assessed using the Gompertz hazard model, and differences in median reported isotope values between the sexes was determined using a Mann Whitney test.Results: It was discovered that higher δ15N levels are associated with elevated risks of mortality, whereas the opposite pattern was observed for δ13C, and males had higher median δ13C and δ15N values.Conclusion: This study successfully demonstrated that stable isotope data can be integrated into hazard models, allowing one to connect diet and mortality in past populations. It supports the findings of other isotope studies which have established that individuals with childhood stress/trauma will have different isotope patterns.

Hazard Analysis and Safety Requirements for Small Drone Operations: To What Extent Do Popular Drones Embed Safety?

Currently, published risk analyses for drones refer mainly to commercial systems, use data from civil aviation, and are based on probabilistic approaches without suggesting an inclusive list of hazards and respective requirements. Within this context, this article presents: (1) a set of safety requirements generated from the application of the systems theoretic process analysis (STPA) technique on a generic small drone system; (2) a gap analysis between the set of safety requirements and the ones met by 19 popular drone models; (3) the extent of the differences between those models, their manufacturers, and the countries of origin; and (4) the association of drone prices with the extent they meet the requirements derived by STPA. The application of STPA resulted in 70 safety requirements distributed across the authority, manufacturer, end user, or drone automation levels. A gap analysis showed high dissimilarities regarding the extent to which the 19 drones meet the same safety requirements. Statistical results suggested a positive correlation between drone prices and the extent that the 19 drones studied herein met the safety requirements generated by STPA, and significant differences were identified among the manufacturers. This work complements the existing risk assessment frameworks for small drones, and contributes to the establishment of a commonly endorsed international risk analysis framework. Such a framework will support the development of a holistic and methodologically justified standardization scheme for small drone flights.

Prognostic efficacy of the human B-cell lymphoma prognostic genes in predicting disease-free survival (DFS) in the canine counterpart.

BACKGROUND: Canine B-cell lymphoma is deemed an ideal model of human non-Hodgkin's lymphoma where the lymphomas of both species share similar clinical features and biological behaviors. However there are some differences between tumor features in both species. In the current study, we sought to evaluate the prognostic efficacy of human B-cell lymphoma prognostic gene signatures in canine B-cell lymphoma. METHODS: The corresponding probe sets of 36 human B-cell lymphoma prognostic genes were retrieved from 2 canine B-cell lymphoma microarray datasets (GSE43664 and GSE39365) (76 samples), and prognostic probe sets were thereafter detected using the univariate and multivariate Cox proportional-hazard model and the Kaplan-Meier analysis. The two datasets were employed both as training sets and as external validation sets for each other. Results were confirmed using quantitative real-time PCR (qRT-PCR) analysis. RESULTS: In the univariate analysis, CCND1, CCND2, PAX5, CR2, LMO2, HLA-DQA1, P53, CD38, MYC-N, MYBL1, and BIRCS5 were associated with longer disease-free survival (DFS), while CD44, PLAU, and FN1 were allied to shorter DFS. However, the multivariate Cox proportional-hazard analysis confirmed CCND1 and BIRCS5 as prognostic genes for canine B-cell lymphoma. qRT-PCR used for verification of results indicated that expression level of CCND1 was significantly higher in B-cell lymphoma patients with the long DFS than ones with the short DFS, while expression level of BIRCS5 wasn't significantly different between two groups. CONCLUSION: Our results confirmed CCND1 as important gene that can be used as a potential predictor in this tumor type.

Urban and rural mortality and survival in Medieval England.

BACKGROUND: Late medieval England underwent intensive urbanisation, particularly in its largest city: London. Urban dwellers were exposed to factors such as high population density, elevated risk of infection, unsanitary living conditions and precarious food supplies. AIM: To assess whether the urban environment was more detrimental to health than the rural environment, this study compares risks of mortality and survival, as proxies for health, in medieval urban vs rural England. SUBJECTS AND METHODS: This study uses samples from rural St. Peter's cemetery in Barton-upon-Humber, Lincolnshire (c. 1150-1500) and urban St. Mary Spital cemetery in London (c. 1120-1539). Cox proportional hazards analysis and Kaplan-Meier survival analysis are used to assess differences in mortality and survival between urban and rural environments, including differences between sexes. RESULTS: The results indicate that urban adults faced elevated risks of dying and reductions in survivorship. Specifically, urban females faced elevated risks of dying and reductions in survivorship, while the risks for males were similar in both environments. DISCUSSION: These results suggest that the effects of urbanisation in medieval England varied by sex. Deleterious conditions associated with urbanisation in London were hazardous for adults, particularly females who may have migrated into London from rural areas for labour opportunities.

Enhanced Hazard Analysis and Risk Assessment for Human-in-the-Loop Systems.

OBJECTIVE: The objective of this study was to enhance the existing system hazard analysis (SHA) technique by introducing the concepts of human and automation reliability quantification as well as fuzzy classification of system risks. These enhancements led to formulation of a new overall system risk-reliability score. BACKGROUND: Many system safety analysis methods focus on individual physical component failure. Some human reliability analyses (HRA) consider human-automation interaction in determining system failure rates. There is no system safety analysis technique that quantifies the impact of human and automation reliability on the risk of hazard exposure. METHOD: Classification of the probability and severity of hazard exposure is typically made in terms of linguistic rather than numerical variables. Fuzzy sets are applicable for transforming linguistic classifications to numerical quantities. We focused on using fuzzy sets to define overlapping bands of system risk exposure with reference to the hazard risk categories defined in MIL-STD 882B. Fuzzy sets were also used for human-automated system reliability classification. RESULTS: Introduction of human and automation reliability assessment in the SHA allows for definition of a system risk-reliability modeling space. The enhanced SHA (E-SHA) technique yields a mishap risk index, which is projected based on a composite assessment of human-automated system reliability at the time of operation. The E-SHA was compared with one of the most advanced HRA techniques. CONCLUSION: The E-SHA technique supports broader safety control recommendations and provides comparable, if not more detailed, results than prior systems safety and HRA techniques.