Societal risk assessment of major hazard installations using QuickRisk

QuickRisk is a quantitative risk assessment tool developed at the Health and Safety Laboratory for use in assessing societal risk around onshore major hazard installations to inform land-use planning decisions. It uses release scenario information, parameterised consequence models, weather data, and population data from the National Population Database (NPD).This paper describes enhancements to the NPD methodology to include workplace populations. It describes the novel numerical, graphical and geographical representations of societal risk produced by QuickRisk. F–N data are analysed in terms of scenario FN curves and Delta PLL vs. N curves, where PLL is potential loss of life. The Delta PLL curves could be useful for comparison of FN curves against FN criterion lines or other FN data on a PLL basis. Geographical representations generated from PLL density maps show: the distribution of PLL dominating release scenarios or the percentage of risk contributed by the PLL-dominant release scenario, the maximum number of fatalities associated with the worst-case event, and the associated release scenario. Geographical representations are also generated of the maximum population that would meet a PLL density criterion, and the relative population change that would match a given PLL density criterion.These novel representations of societal risk could be useful for more effective communication between stakeholders on the risk levels in the vicinity of major hazard installations.     

Results of Finnish national survey in the chemical industry on EU legislation concerned with risk assessment and safety compliance climate

A questionnaire study about the Finnish chemical industry was devised to explore the implementation of the risk assessment obligations of the EU Chemical Agents Directive (98/24/EC), and the role of risk assessment activities as a part of OSH management. The quantitative method involved an assessment of online questionnaire. The respondents were employers' (N = 49) and workers' (N = 105) OSH representatives from different companies'. The regression analysis of the responses indicated that prioritizations in the risk assessment had a highly significant (p < 0.001) effect both on the prevention measures in the management and on the safe use of chemicals. The present results showed that development measures have to be directed at the most important problems ensuring that sub-contractors carry out hazard identification and arranging their on-the-job training so that it matches the chemical plant enterprise's own workers. Furthermore, the results of risk assessment should be used in the planning and management of the work, in the development of the supervisors' leadership skills as well as when following up the improvements.     

Cyclist casualty severity at roundabouts – To what extent do the geometric characteristics of roundabouts play a part?

Introduction: In general, priority junctions are converted into roundabouts to increase capacity and reduce vehicle accidents. However, previous research has indicated that roundabouts are dangerous for vulnerable users, especially cyclists. Method: This paper investigates which design factors influence cyclist casualty severity at give way (non-signalized) roundabouts with mixed traffic, using the UK STATS19 National dataset of cyclist casualties. First, the correlation matrix was generated to observe the relationship between variables. Second, dimension reduction was applied to geometric design variables in order to reduce the number of variables and generate the factors. Finally, the binary logistic regression method, with serious and slight casualties as dependent variables, was applied in three steps. The first Binary Logistic Regression Model (BLRM) included speed limit, sociodemographic, and meteorological conditions. The variables in the second BLRM consisted of geometric design variables. The third BLRM included the factors that were generated by dimension reduction. Results: The correlation matrix revealed that the number of lanes on approach and half width on approach were statistically significantly correlated, while the variables, such as geometric design (entry path radius, number of arms, number of flare lanes on approach, type of roundabout and number of circulating lanes), sociodemographic (casualty gender and age), speed limit and meteorologically related factors (daylight, weather and road surface condition), did not show any statistical significance. From the dimension reduction process, two main factors were identified, including Approach Capacity (Factor 1) and Size of Roundabout (Factor 2), and they were subsequently used as independent variables in the logistic regression analysis. The subsequent BLRMs showed that a higher speed limit reduces the safety for cyclists at roundabouts. The probability of a serious casualty increases by approximately five times (odds ratio 4.97) for each additional number of lanes on approach and by 4% (odds ratio 1.04) with a higher entry path radius. It was also found that Factor 2 (Approach Capacity) increases the casualty severity (odds ratio 1.86) for cyclists at roundabouts. Practical applications: While this research studied roundabouts in the UK, the methodological approach and statistical analysis techniques are applicable to other countries and the findings are likely to be of value to decision makers worldwide.     

Unignited High-Pressure Methane Jet Impinging a Pipe Rack: Practical Tools for Risk Assessment

Although the diffusion of its storage and transport under liquefied conditions, nowadays it is common to have methane in gaseous form in several industrial applications. This leads to safety implications to be considered: hazards are linked to both the high-pressure at which the gas is kept and to its flammability. Scenarios where flammable jets impact an obstacle are of paramount importance because of their possible occurrence. Following a numerical approach, literature shows up that their assessment can be reliably performed by means of only Computational Fluid Dynamics tools. However, despite the improvements of computing power, Computational Fluid Dynamics costs still limit its use in daily risk analysts’ activities. Therefore, considering an accidental jet-obstacle scenario of industrial interest, the present work investigates how a pipe rack can influence the development of a high-pressure methane jet. Based on a Computational Fluid Dynamics analysis, main achievements of this work are a simple criterion able to identify the situations where the pipe rack does not influence the high-pressure methane jet behavior, therefore allowing to identify the scenarios where simpler models can be used (i.e., analytical correlations known for the free jet situation), and, if present, a simple analytical relationship that roughly predicts the influence of the pipe rack without the need of performing complex Computational Fluid Dynamics simulations.     

Experimental and theoretical research on the inhibition performance of ethanol gasoline/air explosion by C6F12O

The safety issue of ethanol gasoline and the methods to control or weaken its explosion have attracted attention. To clarify the effect of C₆F₁₂O (perfluoro(2-methyl-3-pentanone)) on the explosion of ethanol gasoline-air mixtures and intrinsic mechanism, the explosion overpressure and flame propagation behavior under different equivalence ratios (φ = 0.6–0.8) and C₆F₁₂O concentrations (χ_inh = 0–4.0%) were experimentally obtained. The detailed inhibitor reaction process was also obtained by CHEMKIN based on a new assembly kinetic mechanism. The results show that the effects of C₆F₁₂O on the explosion characteristics of ethanol gasoline varied with χ_inh and φ. For rich flames, C₆F₁₂O is more effective than and heptafluoropropane (C₃HF₇) and nitrogen (N₂) in suppressing explosions; for lean and equivalence ratio flames, the addition of C₆F₁₂O may result in more severe explosions. The decrease in chemical reactivity is mainly because the mole fractions of OH and H radicals and the proportion of paths H radicals involved decrease after adding C₆F₁₂O, and R1500: CF₃COF + H = CF₃CO + HF, R965: CF₂:O + H = CF:O + HF, R863: CF₃ + H = CF₂ + HF are main suppressing reactions.     

Pythagorean fuzzy VIKOR-based approach for safety risk assessment in mine industry

Introduction: Underground mining is considered one of the most hazardous industries and is often associated with serious work-related fatalities; this paper addresses job-related hazards and associated risks. Method: A risk assessment approach is proposed (Pythagorean fuzzy environment) and a case study is carried out in an underground copper and zinc mine. Results: Results of the study demonstrate that hazards can be categorized into different risk levels via compromised solutions of the fuzzy approach. Conclusion: The study provides a theoretical contribution by suggesting a Pythagorean fuzzy numbers-based VlseKriterijumska Optimizacija I Kompromisno Resenje (PFVIKOR) approach. Moreover, it contributes to improving overall safety levels of underground mining by considering and advising on the potential hazards of risk management. Practical applications: The proposed approach will improve the existing safety risk assessment mechanism in underground copper and zinc mining.     

Reaction mechanism and process safety assessment of acid-catalyzed synthesis of tert-butyl peracetate

Esterification during the synthesis of tert-butyl peracetate (TBPA) is highly exothermic. Since peroxides (tert-butyl hydroperoxide TBHP and TBPA) are intrinsically thermosensitive, this synthesis process is potentially dangerous. In this work, the exothermic process and mechanism of TBPA synthesis using acetic anhydride (Ac₂O) and TBHP under the catalysis of sulphuric acid (H₂SO₄) were clarified by calorimetry, infrared spectroscopy, and high-performance liquid chromatography. To substantially alleviate the thermal risk of the reaction, and to feasibly select appropriate synthesis conditions for ensuring the process safety of the synthesized products, several sets of isothermal and isoperibol experiments were performed using calorimetry. The intermediates formed and concentration changes during the reaction were monitored using in-situ Fourier-transform infrared spectroscopy. Differential scanning calorimetry and adiabatic calorimetry were used to assess the thermal hazard of the materials during the synthesis process. The reaction mechanism was verified using density functional theory calculations. The results revealed that a controlled increase in exothermicity could be achieved by adding aqueous TBHP to Ac₂O in semi-batch experiments in isothermal mode, and accordingly, the highest yield was 95.71%. Experiments combined with theoretical calculations revealed that the primary exothermic event was the TBPA formation reaction, and the removal of a large amount of water from TBHP prior to this is favourable for the reaction. The criticality classes of this reaction were of Grade 2.     

Cross-cultural comparisons of traffic safety,risk perception,attitudes and behaviour

The core aim of the present study is to examine cultural differences in risk perception and attitudes towards traffic safety and risk, taking behaviour in the Norwegian and the Ghanaian public. An additional aim is to discuss the applicability of various traffic measures, suited for low and middle income countries in Africa.Sample: The results of the present study are based on two self-completion questionnaire surveys carried out in February and March 2006. The first was a representative sample of the Norwegian public above 18 years of age (N = 247). The second was a stratified sample of Ghanaian respondents (N = 299). In Ghana the data was collected in Accra and Cape Coast.The results showed that there is potential for further improvement of safety attitudes and risk behaviour among Ghanaians as well as Norwegians. There were also differences in the respondents’ evaluation of attitudes, risk perception and behaviour. Perceived risk and attitudes also significantly predicted risk behaviour and accidents/collisions. The implications of these results for traffic safety will be discussed.     

Risk assessment methodology for high-pressure CO2 pipelines incorporating topography

This paper presents a risk assessment methodology for high-pressure CO₂ pipelines developed at the Health and Safety Laboratory as part of the EU FP7 project CO2Pipehaz.Traditionally, consequence modelling of dense gas releases from pipelines at major hazard impact levels is performed using integral models with limited or no consideration being given to weather bias or topographical features of the surrounding terrain. Whilst dispersion modelling of CO₂ releases from pipelines using three-dimensional CFD models may provide higher levels of confidence in the predicted behaviour of the cloud, the use of such models is resource-intensive and usually impracticable. An alternative is to use more computationally efficient shallow layer or Lagrangian dispersion models that are able to account for the effects of topography whilst generating results within a reasonably short time frame.In the present work, the proposed risk assessment methodology for CO₂ pipelines is demonstrated using a shallow-layer dispersion model to generate contours from a sequence of release points along the pipeline. The simulations use realistic terrain taken from UK topographical data. Individual and societal risk levels in the vicinity of the pipeline are calculated using the Health and Safety Laboratory's risk assessment tool QuickRisk.Currently, the source term for a CO₂ release is not well understood because of its complex thermodynamic properties and its tendency to form solid particles under specific pressure and temperature conditions. This is a key knowledge gap and any subsequent dispersion modelling, particularly when including topography, may be affected by the accuracy of the source term.     

Predicting pool safety habits and intentions of Australian parents and carers for their young children

Introduction: Children under five years are most at risk of experiencing fatal and nonfatal drowning. The highest proportion of drowning incidents occur in private swimming pools. Lapses in adult supervision and failures in pool barriers are leading contributory factors for pool drowning in this age group. Methods: We investigated the role of the theory of planned behavior social cognitions (attitude, subjective norm, and perceived behavioral control) as well as perceived barriers, planning, role construction, and anticipated regret on parents’ and carers’ intentions and habits toward two pool safety behaviors: restricting access and supervising children around private swimming pools. The study adopted a cross-sectional correlational design. Participants (N = 509) comprised Australian parents or caregivers with children aged under five years and access to a swimming pool at their residence. Participants completed a battery of self-report measures of social cognitive variables with respect to the swimming pool safety behaviors for their children. Results: Path analytic models controlling for past behavior indicated that subjective norm, planning, anticipated regret, and role construction were important predictors of habit, and subjective norm was a consistent predictor of intentions, for both behaviors. Planning predicted intentions in the restricting access sample, while attitudes, barriers, and role construction also predicted intentions in the supervising sample. Both models controlled for past behavior. Conclusion: Current findings indicate the importance of psychological factors for restricting access and supervising behaviors, with normative factors prominent for both reasoned (intentions) and non-conscious (habits) behavioral antecedents. It seems factors guiding restricting access, which likely require regular enactment of routine behaviors (e.g., ensuring gate is not propped open, pool fence meets standards), may be governed by more habitual than intentional processes.     

我国溃坝生命损失评价模型初步研究

根据我国8座已溃决大坝的现场调查结果,结合国内外溃坝生命损失研究成果,初步研究并提出适合我国实际情况的溃坝生命损失评价模型和风险人口死亡率,应用该模型和Graham法估算了这8座水库的溃坝生命损失,与实际生命损失情况进行了比较.结果表明,模型具有一定的适用性.     

A comparison of motorcycle instructor candidate selection practices in the United States

Introduction: An essential aspect of motorcycle rider education is how the instructor selection process impacts student learning, sometimes referred to as the human element, as it is a significant factor influencing curriculum success. Student and program achievements are partially contingent on instructors who understand the curriculum and facilitate student learning during instruction. Previous research on motorcycle rider education has emphasized a need for the examination of instructor selection and development, stating that quality education is reliant on instructors who are competent and qualified. Method: By applying an exploratory study method, state and military Motorcycle Safety Education Program Managers and Instructor Trainers were examined and compared through telephonic interviews to develop a greater understanding of instructor candidate selection criteria and vetting processes. Results: The results suggest that changes in instructor candidate selection systems may improve decisions about a candidate's job and organizational fit. Conclusions: Study conclusions indicate that use of multiple and thorough assessments to determine a candidate’s motivation, social disposition, and emotional intelligence before preparation courses may better identify candidates and align potential job and organization fit within the discipline. Practical Application: Applications of the findings would include a standardized selection process with improved interviews and pre-course auditing, and candidate expectation management before the selection to attend preparation or certification courses. The efforts potentially decrease long-term costs and deficiencies when candidates have an inconsistent job or organizational fit, departing from organizations after short periods or by not providing consistent quality instruction to students. The study recommendations, when implemented, can improve most educational disciplines where instructors are selected for technical instructional positions where students risk injury or harm.     

An experimental investigation of an inertization effectiveness of fluorinated hydrocarbons in relation to premixed H2–N2O and CH4–N2O flames

An experimental investigation of an influence of trifluoromethane CHF_3, pentafluoroethane C₂HF₅ and perfluorobutane C₄F₁₀ on near-limit hydrogen-nitrous oxide and methane-nitrous oxide premixed flames was performed. Flammability limits, a maximum explosion pressure ΔP_max, maximum rate of pressure rise (dP/dt)_max, and a laminar burning velocity S_u were determined. The flammability area in the case of N₂O as an oxidizer is substantially wider than for the case of the oxidizer which is the mixture of oxygen and nitrogen with the O₂ content 25% (vol.). The dependences of S_u, ΔP_max and (dP/dt)_max on concentration of the fluorinated hydrocarbons are characterizing by an availability of maxima which positions are close to the peak concentrations of the flammability regions. A qualitative interpretation of the results obtained is given.     

建筑业人身意外伤害保险探讨

建筑业是伤害事故多发的行业 ,实行建筑业人身意外伤害保险 ,在《中华人民共和国建筑法》和《中华人民共和国安全生产法》里有明确规定 ,也是一项国际惯例。建筑业实施人身意外伤害保险 ,对促进建筑市场和保险市场的发育、减轻企业风险和维护社会稳定意义重大 ,同时有利于建筑业的安全管理以及与国际惯例接轨。目前 ,我国由于企业风险意识薄弱、法规不完善、保险公司不能提供优良的服务以及缺乏保险中介等原因 ,使得意外伤害保险的推行情况不甚理想。为大力推动我国建筑业人身意外伤害保险的发展 ,需要加强风险和保险的宣传、完善配套法规、采取强制与服务并重的措施并扶植我国工程保险中介组织的发展     

The effect of contextual information on professional judgment: Reliability and biasability of expert workplace safety inspectors

Introduction: A critical aspect of occupational safety is workplace inspections by experts, in which hazards are identified. Scientific research demonstrates that expectation generated by context (i.e., prior knowledge and experience) can bias the judgments of professionals and that individuals are largely unaware when their judgments are affected by bias. Method: The current research tested the reliability and biasability of expert safety inspectors’ judgments. We used a two-study design (Study 1, N = 83; Study 2, N = 70) to explore the potential of contextual, task-irrelevant, information to bias professionals’ judgments. We examined three main issues: (1) the effect that biasing background information (safe and unsafe company history) had on professional regulatory safety inspectors’ judgments of a worksite; (2) the reliability of those judgments amongst safety inspectors and (3) inspectors’ awareness of bias in their judgments and confidence in their performance. Results: Our findings establish that: (i) inspectors’ judgments were biased by historical contextual information, (ii) they were not only biased, but the impact was implicit: they reported being unaware that it affected their judgments, and (iii) independent of our manipulations, inspectors were inconsistent with one another and the variations were not a product of experience. Conclusion: Our results are a replication of findings from a host of other professional domains, where honest, hardworking professionals underappreciate the biasing effect of context on their decision making. The current paper situates these findings within the relevant research on safety inspection, cognitive bias and decision making, as well as provides suggestions for bias mitigation in workplace safety inspection. Practical Application: Our results have implications for occupational health and safety given that inspection is an integral aspect of an effective safety system. In addition to our findings, this study contributes to the literature by providing recommendations regarding how to mitigate the effect of bias in inspection.     

A societal risk study for transportation of class-3 hazmats – A case of Indian state highways

United Nations Class-3 hazardous materials (hazmats) are basically liquid products and transported in road tankers under ambient temperature and atmospheric pressure. They are mostly flammables and some of them are toxic (e.g. benzene) as well. The spillages due to collision related incidents involving the road tankers, carrying such hazmats through highways, pose not only flammability hazards due to pool fire, flash fire and vapor cloud explosion (VCE), but create substantial toxic hazards also. The paper presents the risk-based study of route evaluation of two state highways and one urban city road in western India on account of transportation of class-3 hazmats, namely benzene, toluene, p-xylene, methanol, cyclohexane and acetone. A comparative evaluation of study routes was undertaken based on their societal risks presented in terms of F–N curves and assessed against HSE, UK as well as VROM, The Netherlands risk acceptance criteria. Societal risks contribution of cyclohexane to the overall flammability risk mainly VCE is found to be the highest followed by acetone and benzene compared to other study hazmats. This is due to highly explosive nature of cyclohexane resulting into vapor cloud explosion. While acetone and methanol pool fires are likely to cause larger area of damage compared to others, benzene supersedes others as far as toxicity risk is concerned and larger evacuation area is encountered, as it poses greater Immediately Dangerous to Life or Health (IDLH) distance than others. Besides, study of initial isolation distance following an accident in case of benzene tanker found that benzene spillage requires larger initial isolation distance than others and so are the day and night protective action zone distances.     

Extending the J-value framework for safety analysis to include the environmental costs of a large accident

A severe accident on an industrial plant has the potential to cause, in addition to human harm, general damage and hence expense, associated with ground contamination, evacuation of people and business disruption, for example. The total cost of damages, given the name “environmental costs” in this paper, may be comparable with or larger than the cost of direct health consequences, as assessed objectively by the J-value approach. While the low probability of the accident may mean that the expectation of monetary loss is small, the paper develops a utility-based approach to determine how much should be spent on protection systems to protect against both environmental costs and human harm. The behaviour of the fair decision maker in an organisation facing possible environmental costs is represented by an Atkinson Utility function, which is dependent on the organisation's assets and on the elasticity of marginal utility or, equivalently, the coefficient of relative risk aversion, “risk-aversion” for short. A Second Judgment Value, J₂, may be derived from the spend on the protection system after subtracting the amount sanctioned to prevent direct human harm. This net, environmental expenditure is divided by the most that it is reasonable to spend to avert environmental costs at the highest, rational risk-aversion. The denominator in this ratio is found by first calculating the maximum, sensible spend at a risk-aversion of zero, and then multiplying this figure by a Risk Multiplier to give the maximum, fair amount to avert environmental costs. The Risk Multiplier incorporates a risk-aversion that is as large as it can be without rendering the organisation's safety decisions indiscriminate and hence random. An overall, Total Judgment Value, the J_T-value, may also be calculated, which takes into account the reduction in both human harm and environmental cost brought about by the protection system. The new J_T-value will show similar behaviour to the original J-value, in that J_T-values up to unity will indicate reasonable value for money, while J_T-values greater than unity will indicate a prima facie overspend on protection that will need to be justified by further argument. While the analysis is phrased in terms of environmental costs, the treatment is sufficiently general for all costs, including onsite damages, loss of capability etc. to be included. The new, J_T-value method provides for a full and objective evaluation of the worth of any industrial protection system. A worked example is given.     

A case control study of falling incidents among the hospitalized elderly

Falling incidents among the hospitalized elderly were investigated using a case/control methodology to identify high-risk individuals. The medical records of all patients who had a reported fall (N = 173) in 1978 in one geriatric facility were compared with the records of a random sample of patients without a reported fall (N = 339). The significant risk factors were male sex, urinary incontinence within 48 hours prior to the fall, and psychoactive medication 12 hours prior to the fall. It was concluded that some patients may have a greater tendency to fall than others and suggestions for exploring future means of prevention are presented.