Nir Keren

Utilization of accident databases and fuzzy sets to estimate frequency of HazMat transport accidents.

Risk assessment and management of transportation of hazardous materials (HazMat) require the estimation of accident frequency. This paper presents a methodology to estimate hazardous materials transportation accident frequency by utilizing publicly available databases and expert knowledge. The estimation process addresses route-dependent and route-independent variables. Negative binomial regression is applied to an analysis of the Department of Public Safety (DPS) accident database to derive basic accident frequency as a function of route-dependent variables, while the effects of route-independent variables are modeled by fuzzy logic. The integrated methodology provides the basis for an overall transportation risk analysis, which can be used later to develop a decision support system.

Patterns and trends in injuries due to chemicals based on OSHA occupational injury and illness statistics

The Occupational Safety and Health Administration (OSHA) and the Bureau of Labor Statistics (BLS) provide the Survey of Occupational Illness and Injury (SOII) statistics from 1992 to 2006, which is often used to measure the rate of injuries and illness in industry. The present system of gathering and classifying this data was implemented in 1992 with minor changes in 2002. It is hoped that using these statistics to measure safety progress and determine patterns of injury will guide further improvements in chemical safety. Recognizing such factors as what chemicals most frequently cause injury can help to focus safety efforts regarding that chemical. Factors such as what part of the body is most commonly affected by particular chemicals can lead to improved personnel protection practices. This paper provides a detailed analysis of injuries due to chemicals using OSHAs SOII data, which offers valuable insight into measures that should be taken to reduce injuries due to chemicals.

Utility of Baroreflex Sensitivity as a Marker of Stress

Presently, adaptive systems use various cognitive and cardiovascular measures to evaluate the functional state of the operator. One marker that has been largely ignored as an assessment tool is baroreflex sensitivity (BRS). This study examined the extent to which BRS changed in response to acute psychological and physical stressors. A total of 20 participants underwent 6-min exposures to a psychological stressor and a physical stressor. Baroreceptor sensitivity, blood pressure, heart rate, heart rate variability, stroke volume, cardiac output, mean blood pressure, total peripheral resistance, left ventricular ejection time, and pre-ejection period were continuously measured at rest and throughout the testing period. Compared to rest, BRS significantly decreased during both the psychological and physical stressors. BRS was reduced more with the psychological stressor than the physical stressor. Heart rate and systolic blood pressure significantly increased above rest during the psychological stressor but not during the physical stressor. There were no significant differences from rest or between stressors for the other physiological markers. BRS was more robustly responsive than other cardiovascular measures commonly used to assess the psychophysiological response to stress, suggesting BRS is a useful marker for evaluating operator functional state during psychological and physical tasks.

Examining the effect of level of stress on firefighters’ time-to-decision in virtual reality

Highly immersive virtual reality environments were used to examine firefighters’ decision making process and choice. We report here the effects of acute occupationally-relevant stress level on time-to-decision. When comparing low to high-stress situations, time spent on enhancing situational awareness and overall time-to-decision were significantly longer in the low stress setting. However, time spent on reviewing information that was not embedded in the environment was not statically different. Analysis indicated that stress level did not significantly affect the distribution of final choice. We propose that when stress increases, firefighters sacrifice time available to them to enhance their situational awareness rather than sacrifice information review time; however, stress per se, did not affect their decision choice.

Stress Inducing Demands in Virtual Environments

This study investigated how simulated features in a virtual reality (VR) induce stress by means of user-focused demands in serious games. VR serious games have been used for therapeutic interventions, standardized stress tests, and occupational training. However, it is an open question how stress can be induced using serious games formal features, such as tasks/sensory modalities, music, pace of the game, and graphics. The Highrise VR standardized stress simulation was built to induce stress cohesively based on emotional, social, cognitive, and physical demands. The simulation induces stress by requiring coping with emotional demand (innate fear) of being at a simulated height, social demand of being evaluated by researchers, cognitive demand of a mental math task, and physical demand of balancing on a walking-plank. The stress response in participants was measured with two biomarkers: heart rate and salivary cortisol. Heart rate and salivary cortisol both showed significant and prolonged increases in response to the Highrise VR, suggesting that the task can successfully induce a stress response using game features. Among the participants, the response rate to the stressor was 77%, demonstrating a response rate on par with traditional standardized stress tests. Findings from this study warrant further investigation into how VR simulations induce stress for serious games and may add to a new body of literature that uses VR to investigate underlying mechanisms of physiological stress reactivity.

Evaluating the Effectiveness of Graduated Stress Exposure in Virtual Spaceflight Hazard Training

Psychological and physiological stress experienced by astronauts can pose risks to mission success. In clinical settings, gradually increasing stressors help patients develop resilience. It is unclear whether graduated stress exposure can affect responses to acute stressors during spaceflight. This study evaluated psychophysiological responses to potentially catastrophic spaceflight operation, with and without graduated stress exposure, using a virtual reality environment. Twenty healthy participants were tasked with locating a fire on a virtual International Space Station (VR-ISS). After orientation, the treatment group (n = 10) practiced searching for a fire while exposed to a low-level stressor (light smoke), while the control group (n = 10) practiced without smoke. In the testing session, both groups responded to a fire while the VR-ISS unexpectedly filled with heavy smoke. Heart rate variability and blood pressure were measured continuously. Subjective workload was evaluated with the NASA Task Load Index, stress with the Short Stress State Questionnaire, and stress exposure with time-to-complete. During the heavy smoke condition, the control group showed parasympathetic withdrawal, indicating a mild stress response. The treatment group retained parasympathetic control. Thus, graduated stress exposure may enhance allostasis and relaxation behavior when confronted with a subsequent stressful condition.

Development of a Wireless Sensor Network to Quantify Hydrogen Sulfide Concentrations in Swine Housing

Previous research by our team to develop a wireless hydrogen sulfide (H2S) detection system for use in swine housing indicate a multi-point detection system is needed to characterize in-house H2S concentrations both spatially and temporally during slurry agitation. Pulsed fluorescence H2S analyzers, while highly accurate at H2S concentrations less than 20 ppm, require asynchronous sampling to accommodate multiple measurement points with a single analyzer. Additionally, pulsed fluorescence H2S analyzers are not designed to measure the high H2S concentrations associated with burst releases during deep-pit swine manure agitation. The dynamic nature of the environment necessitates simultaneous sampling of multiple points with a sensor that can respond to very high (100 – 500 ppm) H2S concentrations. This can be accomplished through the use of electrochemical sensors that have demonstrated the ability to perform similarly to pulsed fluorescence at high concentrations. The objective of this project was to develop a wireless H2S sensor network that can be used to characterize the spatial distribution of H2S that workers and swine in pork production facilities are exposed to in different facility types during different operating conditions. The wireless H2S sensor network developed in this project was designed to meet the following operational criteria: a) less than 5% sensor drift per 1000 ppm-hours, b) up to 50 m range, c) data collection interval less than 90 seconds, and e) H2S detection range of 0-500 ppm.