Determinants of Airborne Solvent Exposure in the Collision Repair Industry.

Objectives: To assess the determinants of airborne solvent exposures in contemporary vehicle collision repair workplaces. Methods: Personal, full-shift airborne solvent exposures (n = 97) were assessed in 85 vehicle collision repair workers from 18 workshops. Peak exposures were assessed using a small number of video exposure monitoring measurements. Results: Solvent exposures were highest in spray painters (geometric mean = 2.7 ppm) followed by panel beaters (0.5 ppm), but were well below workplace exposure standards. The lowest exposure levels were observed for mixing room extraction located away from the mixing bench [exposure ratio (ER) = 0.51, 95% confidence interval (CI) = 0.30-0.87]. Time spent mixing paint was associated with higher exposures (ER for every 10-min increase = 1.14, 95% CI = 1.05-1.24), as was time spent cleaning equipment with solvents (ER = 1.11, 95% CI = 0.88-1.39), spraying primer (ER = 1.10, 95% CI = 0.96-1.27), and spraying clear coat paint (ER = 1.07, 95% CI = 1.00-1.15). Overall, the combined non-spray painting tasks (mixing paint, degreasing, and cleaning equipment) were more strongly associated with exposure (ER = 1.10, 95% CI = 1.03-1.18) than the combined spray painting tasks (ER = 1.03, 95% CI = 1.00-1.05). Peak exposures ranged from 10 to 1100 ppm with the strongest and most frequent peaks occurring during paint mixing, decanting of solvents, cleaning of equipment, and painting in a cross-draft spray booth. Conclusions: Airborne solvent exposures in the collision repair industry were associated with job title, the design and location of exhaust ventilation and emission sources, and time spent on specific tasks, with the highest average and peak exposures shown for non-spray painting tasks. These findings provide a contemporary basis for intervention programmes to reduce airborne solvent exposures in this industry.

The Effects of Different Levels of Ambient Oxygen in an Oxygen-Enriched Surgical Environment and Production of Surgical Fires.

Surgical fires require an oxygen-enriched environment, a flammable substrate, and an ignition source. We hypothesized ambient oxygen concentration is proportional to the latency time to combustion and the incidence of surgical fires that are detected. We examined latency time and number of events, utilizing the VanCleave et al model of intraoral fire ignition under 60, 80, and 100% oxygen concentration and flow rates of 4 and 10 L/min. Results demonstrated that ambient oxygen concentration and flow rate correlated positively to the initiation of combustion. The number of combustion events with 60% oxygen was significantly lower than with both 80% ( p = .0168) and 100% ( p = .002). Likewise, the number of events with 80% oxygen was significantly lower than with 100% oxygen ( p = .0019). Flow rate has a significant effect on the time to the first event ( p = .0002), time to first audible pop ( p = .0039), and time to first flash or fire ( p < .0001). No combustion occurred at oxygen concentrations less than 60% or flows less than 4 L/min. We conclude that latency time to combustion is directly proportional to ambient oxygen concentration and flow rate. Minimum oxygen concentration and flow rate were identified in our model. Further research is indicated to determine the minimal clinical oxygen concentration and flow rate needed to support combustion of an intraoral fire in a patient.

Wood Dust in Joineries and Furniture Manufacturing: An Exposure Determinant and Intervention Study.

Objectives: To assess wood dust exposures and determinants in joineries and furniture manufacturing and to evaluate the efficacy of specific interventions on dust emissions under laboratory conditions. Also, in a subsequent follow-up study in a small sample of joinery workshops, we aimed to develop, implement, and evaluate a cost-effective and practicable intervention to reduce dust exposures. Methods: Personal inhalable dust (n = 201) was measured in 99 workers from 10 joineries and 3 furniture-making factories. To assess exposure determinants, full-shift video exposure monitoring (VEM) was conducted in 19 workers and task-based VEM in 32 workers (in 7 joineries and 3 furniture factories). We assessed the efficacy of vacuum extraction on hand tools and the use of vacuum cleaners instead of sweeping and dry wiping under laboratory conditions. These measures were subsequently implemented in three joinery workshops with 'high' (>4 mg m-3) and one with 'low' (<2 mg m-3) baseline exposures. We also included two control workshops (one 'low' and one 'high' exposure workshop) in which no interventions were implemented. Exposures were measured 4 months prior and 4 months following the intervention. Results: Average (geometric means) exposures in joinery and furniture making were 2.5 mg m-3 [geometric standard deviations (GSD) 2.5] and 0.6 mg m-3 (GSD 2.3), respectively. In joinery workers cleaning was associated with a 3.0-fold higher (P < 0.001) dust concentration compared to low exposure tasks (e.g. gluing), while the use of hand tools showed 3.0- to 11.0-fold higher (P < 0.001) exposures. In furniture makers, we found a 5.4-fold higher exposure (P < 0.001) with using a table/circular saw. Laboratory efficiency experiments showed a 10-fold decrease in exposure (P < 0.001) when using a vacuum cleaner. Vacuum extraction on hand tools combined with a downdraft table reduced exposures by 42.5% for routing (P < 0.1) and 85.5% for orbital sanding (P < 0.001). Following intervention measures in joineries, a borderline statistically significant (P < 0.10) reduction in exposure of 30% was found in workshops with 'high' baseline exposures, but no reduction was shown in the workshop with 'low' baseline exposures. Conclusions: Wood dust exposure is high in joinery workers and (to a lesser extent) furniture makers with frequent use of hand tools and cleaning being key drivers of exposure. Vacuum extraction on hand tools and alternative cleaning methods reduced workplace exposures substantially, but may be insufficient to achieve compliance with current occupational exposure limits.

Solvent neurotoxicity in vehicle collision repair workers in New Zealand.

OBJECTIVES: To assess whether solvent use and workplace practices in the vehicle collision repair industry are associated with symptoms of neurotoxicity in spray painters and panel beaters (auto body repair workers). METHODS: Neurobehavioural symptoms were assessed using a cross-sectional study design in 370 vehicle collision repair and 211 reference workers using the EUROQUEST questionnaire. Full-shift airborne solvent levels were measured in a subset (n=92) of collision repair workers. RESULTS: Solvent exposures were higher in spray painters than in panel beaters, but levels were below current international exposure standards. Collision repair workers were more likely to report symptoms of neurotoxicity than reference workers with ORs of 2.0, 2.4 and 6.4 (all p<0.05) for reporting ≥5, ≥10 and ≥15 symptoms respectively. This trend was generally strongest for panel beaters (ORs of 2.1, 3.3 and 8.2 for ≥5, ≥10 and ≥15 symptoms respectively). Associations with specific symptom domains showed increased risks for neurological (OR 4.2), psychosomatic (OR 3.2), mood (OR 2.1), memory (OR 2.9) and memory and concentration symptoms combined (OR 2.4; all p<0.05). Workers who had worked for 10-19 years or 20+ years in the collision repair industry reported consistently more symptoms than those who had only worked less than 10 years even after adjusting for age. However, those who worked more than 20 years generally reported fewer symptoms than those who worked 10-19 years, suggesting a possible healthy worker survivor bias. CONCLUSIONS: Despite low airborne solvent exposures, vehicle collision repair spray painters and panel beaters continue to be at risk of symptoms of neurotoxicity.

Efficiency of Airborne Sample Analysis Platform (ASAP) bioaerosol sampler for pathogen detection.

The threat of bioterrorism and pandemics has highlighted the urgency for rapid and reliable bioaerosol detection in different environments. Safeguarding against such threats requires continuous sampling of the ambient air for pathogen detection. In this study we investigated the efficacy of the Airborne Sample Analysis Platform (ASAP) 2800 bioaerosol sampler to collect representative samples of air and identify specific viruses suspended as bioaerosols. To test this concept, we aerosolized an innocuous replication-defective bovine adenovirus serotype 3 (BAdV3) in a controlled laboratory environment. The ASAP efficiently trapped the surrogate virus at 5 × 10(3) plaque-forming units (p.f.u.) [2 × 10(5) genome copy equivalent] concentrations or more resulting in the successful detection of the virus using quantitative PCR. These results support the further development of ASAP for bioaerosol pathogen detection.

An iOS Application for Evaluating Whole-body Vibration Within a Workplace Risk Management Process.

Workplace management of whole-body vibration exposure requires systematic collection of whole-body vibration data in conjunction with the numerous variables which influence vibration amplitudes. The cost and complexity of commercially available measurement devices is an impediment to the routine collection of such data by workplaces. An iOS application (WBV) has been developed which allows an iPod Touch to be used to measure whole-body vibration exposures. The utility of the application was demonstrated by simultaneously obtaining 98 pairs of whole-body vibration measurements from both the iPod Touch application and a commercially available whole-body vibration device during the operation of a variety of vehicles and mobile plant in operation at a surface coal mine. The iOS application installed on a fifth-generation iPod Touch was shown to provide a 95% confidence of +/- 0.077 m/s(2) r.m.s. constant error for the vertical direction. Situations in which vibration levels lay within the ISO2631.1 health guidance caution zone were accurately identified, and the qualitative features of the frequency spectra were reproduced. The low cost and relative simplicity of the application has potential to facilitate its use as a screening tool to identify situations in which musculoskeletal disorders may arise as a consequence of exposure to whole-body vibration.

The effect of intraoral suction on oxygen-enriched surgical environments: a mechanism for reducing the risk of surgical fires.

In this study, a mechanical model was applied in order to replicate potential surgical fire conditions in an oxygen-enriched environment with and without high-volume suction typical for dental surgical applications. During 41 trials, 3 combustion events were measured: an audible pop, a visible flash of light, and full ignition. In at least 11 of 21 trials without suction, all 3 conditions were observed, sometimes with an extent of fire that required early termination of the experimental trial. By contrast, in 18 of 20 with-suction trials, ignition did not occur at all, and in the 2 cases where ignition did occur, the fire was qualitatively a much smaller, candle-like flame. Statistically comparing these 3 combustion events in the no-suction versus with-suction trials, ignition (P = .0005), audible pop (P = .0211), and flash (P = .0092) were all significantly more likely in the no-suction condition. These results suggest a possible significant and new element to be added to existing surgical fire safety protocols toward making surgical fires the "never-events" they should be.

Evaluation and control of waste anesthetic gases in the postanesthesia care unit.

BACKGROUND: Few studies have addressed waste anesthetic gases (WAGs) in the postanesthesia care unit (PACU) related to exhaled sevoflurane and nitrous oxide. PURPOSE: To evaluate the effectiveness of a new scavenging system to control WAGs in the PACU. DESIGN: Comparative and descriptive study. METHODS: This pilot study compared exposure to WAGs with and without a scavenging system using infrared technology to visualize and quantify exposure to these gases in the PACU. FINDING: The results showed a significant reduction (P < .05) in both nitrous oxide and sevoflurane at both six inches and three feet from the patient's breathing zone, as well as in the work area of the perianesthesia nurses in the PACU. CONCLUSIONS: WAG exposure may be more easily managed through the use of this new scavenging system to better control occupational exposures to these gases among PACU personnel.

Factors involved in dental surgery fires: a review of the literature.

Surgical fires are well-characterized, readily preventable, potentially devastating operating room catastrophes that continue to occur from 20 to 100 times per year or, by one estimate, up to 600 times per year in US operating rooms, sometimes with fatal results. The most significant risk factors for surgical fires involve (a) the use of an ignition source, such as laser or electrocautery equipment, in or around an oxygen-enriched environment in the head, neck, and upper torso area and (b) the concurrent delivery of supplemental oxygen, especially via nasal cannula. Nonetheless, while these 2 conditions occur very commonly in dental surgery, especially in pediatric dental surgery where sedation and anesthesia are regularly indicated, there is a general absence of documented dental surgical fires in the literature. Barring the possibility of underreporting for fear of litigation, this may suggest that there is another mechanism or mechanisms present in dental or pediatric dental surgery that mitigates this worst-case risk of surgical fires. Some possible explanations for this include: greater fire safety awareness by dental practitioners, incidental ventilation of oxygen-enriched environments in patient oral cavities due to breathing, or suction used by dental practitioners during procedures. This review of the literature provides a background to suggest that the practice of using intraoral suction in conjunction with the use of supplemental oxygen during dental procedures may alter the conditions needed for the initiation of intraoral fires. To date, there appear to be no published studies describing the ability of intraoral suctioning devices to alter the ambient oxygen concentration in an intraoral environment. In vivo models that would allow examination of intraoral suction on the ambient oxygen concentration in a simulated intraoral environment may then provide a valuable foundation for evaluating the safety of current clinical dental surgical practices, particularly in regard to the treatment of children.

Evaluation of cut-off saw exposure control methods for respirable dust and crystalline silica in roadway construction.

Dust reduction equipment adapted for single-person operation was evaluated for gas-powered, commercially available cut-off saws during concrete curb cutting. Cutting was performed without dust control and with two individual exposure control methods: wet suppression and local exhaust ventilation (LEV). The wet suppression system comprised a two-nozzle spray system and a 13.3-L hand-pressurized water supply system with an optimum mean flow rate of 0.83 L/min for 16 min of cutting. The LEV system consisted of a spring-loaded guard, an 18.9-L collection bag, and a centrifugal fan with an estimated exhaust rate of 91 ft(3)/min. Task-based, personal filter samples were obtained for four saw operators during cutting durations of 4 to 16 min on five job sites. Seventeen filter samples were collected without dust control, 14 with wet suppression, and 12 with LEV, yielding a geometric mean respirable dust concentration of 16.4 mg/m(3), 3.60 mg/m(3), and 4.40 mg/m(3), respectively. A dust reduction of 78.0% for wet suppression and 73.2% for LEV was observed vs. no dust control. A statistically significant difference (p < 0.001) was also revealed for wet suppression and LEV when compared with no dust control; however, a significant difference (p = 0.09) was not observed between wet suppression and LEV. Despite these significant dust reductions, workers are still projected to exceed the ACGIH 8-hr time-weighted average threshold limit value for quartz (0.025 mg/m(3)) in less than 1 hr of cutting for both dust control methods. Further research is still needed to improve dust reduction and portability of both control methods, but the current LEV system offers important advantages, including a drier, less slippery work area and year-round functionality in cold weather.

Ergonomics. The effect of occupational exposure to environmental tobacco smoke on the heart rate variability of bar and restaurant workers.

Changes in heart rate variability (HRV) have been linked with cardiac disease and death. Exposure to particulate matter from various sources such as tobacco smoke has been shown to cause alterations in HRV. This study investigated the effects of occupational exposure to environmental tobacco smoke (ETS) on HRV. Air monitoring was conducted in three bars in which smoking was permitted and one bar where smoking was not permitted. Pre- and post-work shift heart rate monitoring was conducted on volunteer staff from the establishments. Heart rate variability parameters, including SDNN and RMSSD, were calculated, and the differences between pre- and post-shift values were plotted and analyzed with respect to ETS exposure. Post-shift minus pre-shift values of SDNN and RMSSD significantly decreased with exposure to ETS (p < 0.05). Occupational exposure to ETS may decrease heart rate variability.

Limited economic evaluation to assess the effectiveness of a university-wide office ergonomics program.

The objective of this research was to evaluate the effectiveness and provide a limited economic evaluation of an office ergonomics program at a major university from 1995 to 2007. The relationship between office-related recordable injuries, reported lost time, severity of these injuries, and the Workers' Compensation (WC) paid was analyzed and the corresponding incident cost was calculated. Two major datasets analyzed were OSHA 200/300 logs (1991-2007) and WC claims paid (1999-2007). Since the beginning of the office ergonomics program in 1995 and through 2007 (13-year period), the number of office cumulative trauma disorder (CTD) cases decreased by 53%. Since the official start (in 1999) of a 50-50 cost share agreement for office equipment purchases between the university's Safety and Health Department (SHD) and the university departments evaluated, it was observed that the incident rate decreased by 63%, Total Days Away/restrict or Transfer (DART) rate decreased by 41%, Lost Time Case (LTC) rate decreased by 71% and office-related carpal tunnel syndrome decreased by almost 50%. The long-term goal of this research is to demonstrate the self-sustainability of an office ergonomics program by showing that equipment costs are eventually offset by a decrease in WC claims paid and lost time from office-related injuries and illnesses. While limited, this research helps in cost-justifying the implementation of future office ergonomics programs for large organizations.

Evaluation of lifestyle risk factors and job status associated with back injuries among employees at a mid-western university.

For decades the literature has shown an association between work-related risk factors and back injuries among employees. However, only recently, there is a growing body of literature that suggests lifestyle risk factors may also be associated with back injuries. The purpose of this research was to determine if selected lifestyle risk factors are associated with a greater risk of back injuries. Further, there may be an association between job status and incident reporting, lost workdays cases and workers' compensation (WC) paid for back injuries among university employees. Aggregate data from a Health Risk Assessment (HRA) questionnaire were used to analyze 6053 university employees for lifestyle risk factors associated with back injuries. Of the total sample, 57% (n=3471) were female; 46% (n=2778) worked as clerical or service staff; and the mean age was 45years. Pearson chi-square (chi(2)) analyses indicate that job status (chi(2)=307.07, df=4, p<.001) and gender (chi(2)=40.14, df=2, p<.001) were associated with high risk back score. An ordinal regression analysis predicted that participants who exercised vigorously for at least 20min, 3 or more days per week, or 3 or more days per week of combined vigorous exercise and moderate-intensity physical activity are almost 30 times less likely to have a high back risk score compared to participants who do not exercise vigorously or participate in less than 3days per week of moderate-intensity physical activity (OR=29.68, 95% CI=25-35.25, p<.001). Participants who have a low risk score for BMI are three times less likely (OR=3.20, 95% CI=2.74-3.75, p<.001) to have a high back risk score when compared to participants who have a high risk score for BMI. A regression tree predicted high back risk scores were participants who: (1) receive an adequate amount of physical activity or vigorous exercise and is a male service or clerical staff; (2) do not receive an adequate amount of physical activity or vigorous exercise, and is not overweight; or (3) who do not receive an adequate amount of physical activity or vigorous exercise, and is overweight. Six years of Occupational Safety and Health Administration (OSHA) 300 logs and WC claims data paid for back injuries supported the finding that clerical or service staff had the greatest risk of back injuries. Based on the results of this study, there appears to be an association between lifestyle risk factors, job status and back injuries among university employees. We believe our evaluation approach may be used to study other work populations to verify the outcomes observed in this study.

Ergonomics case study: revised NIOSH lifting equation instruction issues for students.

This case study investigated the effectiveness of formal instruction of the Revised NIOSH Lifting Equation for university students who may use the equation in their future work. Their successes and challenges were examined through a class exercise and two exams, all of which followed the classroom instruction in applying the Lifting Equation. Results showed students (1) had difficulty determining relevant values for task variables from reading a job description, and (2) generally were able to calculate the Recommended Weight Limit (RWL) and Lifting Index (LI) when task variables were such that the associated multipliers were less than or equal to 1. However, when the multiplier was calculated to be greater than 1, students had difficulty interpreting the result. The task variable and multiplier (consistently the greatest challenge) were the asymmetry task variable, A, and the asymmetric multiplier, AM. Results indicate that the layout of the Job Analysis Worksheet for Step 1 may make it easy to make arithmetic errors when calculating multipliers. It is recommended that the worksheet be redesigned to help individuals decrease the probability of making an arithmetic error when calculating the task variables, multipliers, RWL, and LI. It is also recommended that the redesigned worksheet be tested to determine whether fewer arithmetic errors are made and if the worksheet is less confusing for an inexperienced user to use.

Evaluation of two nitrous oxide scavenging systems using infrared thermography to visualize and control emissions.

BACKGROUND: The authors conducted a study to determine the effectiveness of two waste anesthetic gas-scavenging systems. They also evaluated one of the systems to determine the effect of work practices in controlling waste nitrous oxide (N2O). METHODS: The authors collected a minimum of 13 data sets in each phase of the study that included infrared thermography, digital videography and real-time air analysis for ambient concentrations of waste N2O. Surgeon 1, who had experience using both systems, used the Safe Sedate Dental Mask (Airgas, Radnor, Pa.) system (system I) in phase I and the Porter Nitrous Oxide Sedation System (Porter Instruments, Hatfield, Pa.) (system II) in phase II. Surgeon 2, who did not have experience using system I, used it in phase III. To evaluate each system's effectiveness, the authors collected N2O air concentration data from phases I and II and compared the data with the National Institute for Occupational Safety and Health Recommended Exposure Limit (NIOSH REL). They also compared phases I and III to determine the effect of work practices on the systems' effectiveness. RESULTS: Surgeon 1 controlled occupational exposure to N2O significantly better using system I than using system II. Mean N2O air concentration levels during phases I and II were 61.6 parts per million (ppm) and 225.6 ppm, respectively. Surgeon 2 did not achieve results comparable to those of surgeon 1 in phase I using system I. Infrared thermography and air concentration data suggested that key work practices and patient and surgical variables accounted for the different results obtained in phases I and III. CONCLUSIONS: Although neither system was able to control occupational exposure of N2O oxide below the NIOSH REL, system I met the American Conference of Governmental Industrial Hygienists threshold limit value of less than 50 ppm during an eight-hour day and performed significantly better than did system II. CLINICAL IMPLICATIONS: System I achieved maximal efficiency when combined with consistent best work practices.

A vicious cycle in the oral health status of schoolchildren in a primary school in rural Cambodia.

OBJECTIVE: To investigate the oral health status and the risk factors contributing to dental caries and gum disease of schoolchildren in Cambodia. METHODS: A cross-sectional survey was conducted in a primary school in the Puok District, Siem Reap Province of Cambodia. An oral examination and self-reported questionnaire were used to evaluate oral health status of schoolchildren, ranging in age from 6-16. Of the 512 children that were enrolled in first through sixth grade at the primary school, 332 children (62.8%) participated. RESULTS: Of the schoolchildren that were involved in this study, the prevalence of dental caries in permanent dentition was 53.5% and gum disease was present in 46.2%. Among the participants 80% had plaque, 68.6% suffered from tooth pain and only 44.2% of the schoolchildren owned their own toothbrush. There was an association between the schoolchildren that suffered from tooth pain and those that had dental caries (P < 0.03). Plaque was related to dental caries in permanent dentition (P < 0.003), calculus (P < 0.0001) and gum disease (P < 0.0001) and was linked to the schoolchildren who did not own a toothbrush (P < 0.03) and who suffered from tooth pain (P < 0.03). CONCLUSION: The following sequence of events may result in a vicious cycle in the oral healthcare of schoolchildren in rural Cambodia: the lack of a personal toothbrush leads to plaque buildup, which may increase the incidence of dental caries, which has been linked to tooth pain and gum disease. Ultimately, this poor oral healthcare impacts an individual's quality of life and can lead to more serious health issues later in life.