Unlatching school bus seat belt buckles: Considerations for young passengers

Automobile seat belts reduce the risk of injuries and fatalities resulting from a crash. As seat belts become more prevalent on large school buses, characterizing the capabilities of children to operate the unlatching mechanism of a seat belt is crucial to ensure the post-crash safety of young passengers. This study evaluated the strength capabilities of children and their abilities to unlatch a school bus seat belt when a school bus is in both the upright and rolled-over orientations. Push force exertions on a seat belt buckle push button were measured and compared to the seat belt assembly release force requirements specified in Federal Motor Vehicle Safety Standard (FMVSS) No. 209. Results of the study suggested that children do not have the strength to exert the maximum force of 133 N to release a seat belt assembly as specified in FMVSS No. 209; however, most children could unlatch a typical school bus seat belt assembly in the upright and rolled-over orientations.

Morphology and Composition of Lumbar Intervertebral Discs: Comparative Analyses of Manual Measurement and Computer-Assisted Algorithms

BACKGROUND

The morphology and internal composition, particularly the nucleus-to-cross sectional area (NP-to-CSA) ratio of the lumbar intervertebral discs (IVDs), is important information for finite element models (FEMs) of spinal loadings and biomechanical behaviors, and, yet, this has not been well investigated and reported.

METHODS

Anonymized MRI scans were retrieved from a previously established database, including a total of 400 lumbar IVDs from 123 subjects (58 F and 65 M). Measurements were conducted manually by a spine surgeon and using two computer-assisted segmentation algorithms, i.e., fuzzy C-means (FCM) and region growing (RG). The respective results were compared. The influence of gender and spinal level was also investigated.

RESULTS

Ratios derived from manual measurements and the two computer-assisted algorithms (FCM and RG) were 46%, 39%, and 38%, respectively. Ratios derived manually were significantly larger.

CONCLUSIONS

Computer-assisted methods provide reliable outcomes that are traditionally difficult for the manual measurement of internal composition. FEMs should consider the variability of NP-to-CSA ratios when studying the biomechanical behavior of the spine.

Estimating Compressive and Shear Forces at L5-S1: Exploring the Effects of Load Weight, Asymmetry, and Height Using Optical and Inertial Motion Capture Systems

This study assesses the agreement of compressive and shear force estimates at the L5-S1 joint using inertial motion capture (IMC) within a musculoskeletal simulation model during manual lifting tasks, compared against a top-down optical motion capture (OMC)-based model. Thirty-six participants completed lifting and lowering tasks while wearing a modified Plug-in Gait marker set for the OMC and a full-body IMC set-up consisting of 17 sensors. The study focused on tasks with variable load weights, lifting heights, and trunk rotation angles. It was found that the IMC system consistently underestimated the compressive forces by an average of 34% (975.16 N) and the shear forces by 30% (291.77 N) compared with the OMC system. A critical observation was the discrepancy in joint angle measurements, particularly in trunk flexion, where the IMC-based model underestimated the angles by 10.92-11.19 degrees on average, with the extremes reaching up to 28 degrees. This underestimation was more pronounced in tasks involving greater flexion, notably impacting the force estimates. Additionally, this study highlights significant differences in the distance from the spine to the box during these tasks. On average, the IMC system showed an 8 cm shorter distance on the X axis and a 12-13 cm shorter distance on the Z axis during lifting and lowering, respectively, indicating a consistent underestimation of the segment length compared with the OMC system. These discrepancies in the joint angles and distances suggest potential limitations of the IMC system's sensor placement and model scaling. The load weight emerged as the most significant factor affecting force estimates, particularly at lower lifting heights, which involved more pronounced flexion movements. This study concludes that while the IMC system offers utility in ergonomic assessments, sensor placement and anthropometric modeling accuracy enhancements are imperative for more reliable force and kinematic estimations in occupational settings.

The Combined Impact of Hand-Arm Vibration and Noise Exposure on Hearing Sensitivity of Agricultural/Forestry Workers-A Systematic Literature Review

Hand-arm vibration (HAV), which potentially causes vibration white finger (VWF), and occupational noise are serious issues in the agricultural and forestry industries. Generally, agricultural workers operate as single-family/small businesses and thus are exempted from Occupational Safety and Health Administration (OSHA) regulations/laws for noise and HAV otherwise applicable to other industries in general. The agricultural/forestry sectors are at increased risk as working hours are longer than a typical 8-h work shift putting them at greater risk of hearing loss. The study was conducted to assess the possible association between hearing sensitivity on combined exposure to noise and hand-arm vibration. A systematic literature review was conducted on exposure to noise and HAV in the agricultural/forestry sector and the resulting impacts on hearing. The peer-reviewed articles in English were searched with 14 search words in three databases of PubMed, Ergo Abstracts, and Web of Science without any filter for the year for fully available article text. The database literature search resulted in 72 articles. Forty-seven (47) articles met the search criteria based on the title. Abstracts were then reviewed for any relationship between hearing loss and hand-arm vibration/Raynaud's phenomenon/VWF. This left 18 articles. It was found that most agricultural workers and chainsaw workers are exposed to noise and VWF. Hearing is impacted by both noise and aging. The workers exposed to HAV and noise had greater hearing loss than non-exposed workers, possibly due to the additive effect on temporary threshold shift (TTS). It was found that VWF might be associated with vasospasm in the cochlea through autonomous vascular reflexes, digital arteries narrowing, vasoconstriction in the inner ear by noise, ischemic damage to the hair cells and increased oxygen demand, which significantly affects the correlation between VWF and hearing loss.

Reliability Analysis of Observation-Based Exposure Assessment Tools for the Upper Extremities: A Systematic Review

(1) Background: The objectives of this systematic review were to (i) summarize the results of studies evaluating the reliability of observational ergonomics exposure assessment tools addressing exposure to physical risk factors associated with upper extremity musculoskeletal disorders (MSDs), and (ii) identify best practices for assessing the reliability of new observational exposure assessment tools. (2) Methods: A broad search was conducted in March 2020 of four academic databases: PubMed, Science Direct, Ergonomic Abstracts, and Web of Science. Articles were systematically excluded by removing redundant articles, examining titles and abstracts, assessing relevance to physical ergonomics and the upper extremities, and article type. (3) Results: Eleven articles were included in the review. The results indicated no singular best practice; instead, there were multiple methodological approaches researchers chose to use. Some of the significant variations in methodologies include the selection of reliability coefficients, rater and participant selection, and direct vs. digital observation. (4) Conclusion: The findings serve as a resource summarizing the reliability of existing observational risk assessment tools and identify common methods for assessing the reliability of new observational risk assessment tools. Limitations of this review include the number of databases searched, the removal of truncation symbols, and the selection of keywords used for the initial search.

Manufacturing worker perceptions of using wearable inertial sensors for multiple work shifts

Wearable inertial sensors may be used to objectively quantify exposure to some physical risk factors associated with musculoskeletal disorders. However, concerns regarding their potential negative effects on user safety and satisfaction remain. This study characterized the self-reported daily discomfort, distraction, and burden associated with wearing inertial sensors on the upper arms, trunk, and dominant wrist of 31 manufacturing workers collected over 15 full work shifts. Results indicated that the workers considered the devices as generally comfortable to wear, not distracting, and not burdensome to use. Exposure to non-neutral postures (discomfort, right arm, beta = 0.02; trunk, beta = -0.01), non-cyclic tasks (distraction, beta = -0.26), and higher body mass indices (discomfort, beta = 0.05; distraction, beta = 0.02) contributed to statistically significant (p < 0.05), albeit practically small increases in undesirable ratings. For instance, for each additional percentage of time working with the right arm elevated ≥60°, self-reported discomfort ratings increased 0.02 cm on a standard 10 cm visual analog scale. Female workers reported less discomfort and distraction while wearing the sensors at work than males (discomfort, beta = -0.93; distraction, beta = -0.3). In general, the low ratings of discomfort, distraction, and burden associated with wearing the devices during work suggests that inertial sensors may be suitable for extended use among manufacturing workers.

Development and validation of a cumulative exposure shoulder risk assessment tool based on fatigue failure theory

OBJECTIVE

To present a new risk assessment tool for shoulder intensive occupational tasks based on fatigue failure theory.

METHODS

The tool estimates cumulative damage (CD) based on shoulder moments and loading cycles using an S-N curve derived from in vitro tendon fatigue failure tests. If multiple shoulder tasks are performed, the CD for each is summed. In the validation, 293 workers were evaluated for five separate shoulder outcomes. Logistic regression was used to assess the log CD against five shoulder outcomes adjusted for covariates including age, sex, body mass index (BMI), and plant site.

RESULTS

Both crude and adjusted logistic regression results demonstrated strong dose-response associations between the log CD measure and all five shoulder outcomes (continuous ORs ranged from 2.12 to 5.20).

CONCLUSIONS

The CD measure of The Shoulder Tool demonstrated dose-response relationships with multiple health outcomes. This provides further support that MSDs may be the result of a fatigue failure process.

PRACTITIONER SUMMARY

This study presents a new, easy-to-use risk assessment tool for occupational tasks involving stressful shoulder exertions. The tool is based on fatigue failure theory. The tool was tested against an existing epidemiology study and demonstrated strong relationships to multiple shoulder outcomes.

ABBREVIATIONS

MSD: musculoskeletal disorder; NORA: national occupational research agenda; RULA: rapid upper limb assessment; REBA: rapid entire body assessment; S-N: stress-number of cycles; EDL: extensor digitorum longus; DPC: damage per cycle; CD: cumulative damage; UTS: ultimate tensile strength; FTOV: first time office visit; 3DSSPP: 3-dimensional static strength prediction program; AS: visual analogue scale; BMI: body mass index; CI: confidence interval; Nm: newton-metre; LiFFT: lifting fatigue failure tool; DUET: distal upper extremity tool; OMNI-RES: OMNI resistance exercise scale.

Development and validation of a cumulative exposure shoulder risk assessment tool based on fatigue failure theory

OBJECTIVE

To present a new risk assessment tool for shoulder intensive occupational tasks based on fatigue failure theory.

METHODS

The tool estimates cumulative damage (CD) based on shoulder moments and loading cycles using an S-N curve derived from in vitro tendon fatigue failure tests. If multiple shoulder tasks are performed, the CD for each is summed. In the validation, 293 workers were evaluated for five separate shoulder outcomes. Logistic regression was used to assess the log CD against five shoulder outcomes adjusted for covariates including age, sex, body mass index (BMI), and plant site.

RESULTS

Both crude and adjusted logistic regression results demonstrated strong dose-response associations between the log CD measure and all five shoulder outcomes (continuous ORs ranged from 2.12 to 5.20).

CONCLUSIONS

The CD measure of The Shoulder Tool demonstrated dose-response relationships with multiple health outcomes. This provides further support that MSDs may be the result of a fatigue failure process.

PRACTITIONER SUMMARY

This study presents a new, easy-to-use risk assessment tool for occupational tasks involving stressful shoulder exertions. The tool is based on fatigue failure theory. The tool was tested against an existing epidemiology study and demonstrated strong relationships to multiple shoulder outcomes.

ABBREVIATIONS

MSD: musculoskeletal disorder; NORA: national occupational research agenda; RULA: rapid upper limb assessment; REBA: rapid entire body assessment; S-N: stress-number of cycles; EDL: extensor digitorum longus; DPC: damage per cycle; CD: cumulative damage; UTS: ultimate tensile strength; FTOV: first time office visit; 3DSSPP: 3-dimensional static strength prediction program; AS: visual analogue scale; BMI: body mass index; CI: confidence interval; Nm: newton-metre; LiFFT: lifting fatigue failure tool; DUET: distal upper extremity tool; OMNI-RES: OMNI resistance exercise scale.

Increasing evacuation flow through school bus emergency roof hatches

Emergency escape roof hatches are used to evacuate school buses in rolled-over orientations. In the United States, the minimum opening size of a roof hatch is defined by Federal Motor Vehicle Safety Standard (FMVSS) no. 217. With the prevalence of rising obesity rates among children, the minimum roof hatch opening size may not be large enough to accommodate larger passengers. Post-accident conditions such as injuries, disorientation, and exit obstructions may also prevent unobstructed passage for egress within acceptable time limits. The purpose of this study was to redesign and fabricate a roof hatch with a larger opening and evaluate its egress characteristics for a range of typical school bus passengers. The larger roof hatch opening allows greater evacuation flow rates, and is almost functionally equivalent to the evacuation flow rate of the front door on an upright school bus.

Regression models for the erector spinae muscle (ESM) cross-sectional area (CSA): Asymptomatic populations

Understanding low back morphology is critical to understanding spinal loading and the underlying injury mechanisms, which helps to characterize risk and, therefore, minimize low back pain injuries. Individualized erector spinae muscle (ESM) cross-sectional area (CSA) allows biomechanics practitioners to calculate individualized force-generating capacities and spinal loadings for given tasks. The objective is to perform morphological analyses and then provide regression models to estimate the ESM CSA of an individual with his/her subject characteristics. Thirty-five subjects (13 females and 22 males) without LBP history were included in this MRI study. Axial-oblique scans of the low back region were used to measure the ESM CSA. Subject demographics and anthropometrics were obtained and regressed over the ESM CSA. Best-subset regression analyses were performed. Lean body mass and the ankle, wrist, and head indexes were the most frequent predictive variables. Regression models with easy-to-measure variables showed smaller predictive power and increased estimation error compared to other regression models. Practitioners should consider this trade-off between model accuracy and complexity. An individual's ESM CSA could be estimated by his/her individual characteristics, which enables biomechanical practitioners to estimate individualized low back force capacity and spinal loading.

Incidence of Intravenous Medication Errors in a Chinese Hospital

OBJECTIVES

The purpose of this study was to explore intravenous (IV) medication errors in a Chinese hospital. The specific objectives were to 1) explore and measure the frequency of IV medication errors by direct observation and identify clues to their causes in Chinese hospital inpatient wards and 2) identify the clinical importance of the errors and find the potential risks in the preparation and administration processes of IV medications.

METHODS

A prospective study was conducted by using the direct observational method to describe IV medication errors on two general surgery patient wards in a large teaching hospital in Beijing, China. A trained observer accompanied nurses during IV preparation rounds to detect medication errors. The difference in mean error rates between total parenteral nutrition (TPN) and non-TPN medications was tested by using the Mann-Whitney U test.

RESULTS

A final total of 589 ordered IV doses plus 4 unordered IV doses as prepared and administered to the patients was observed from August 3, 2010, to August 13, 2010. The overall error rate detected on the study ward was 12.8%. The most frequent errors by category were wrong dose (5.4%), wrong time (3.7%), omission (2.7%), unordered dose (0.7%), and extra dose (0.3%). Excluding wrong time errors, the error rate was 9.1%. Non-TPN medications had significantly higher error rates than did TPN medications including wrong time errors (P = 0.0162).

CONCLUSIONS

A typical inpatient in a Chinese hospital was subject to about one IV error every day. Pharmacists had a very limited role in ensuring the accuracy of IV medication preparation and administration processes.

Job Level Risk Assessment Using Task Level Strain Index Scores: A Pilot Study

This paper explores 2 methods of modifying the Strain Index (SI) to assess the ergonomic risk of multi-task jobs. Twenty-eight automotive jobs (15 cases and 13 controls) were studied. The first method is based on the maximum task SI score, and the second method is modeled on the NIOSH Composite Lifting Index (CLI) algorithm, named cumulative assessment of risk to the distal upper extremity (CARD). Significant odds ratios of 11 (CI 1.7-69) and 24 (CI 2.4-240) were obtained using the modified maximum task and CARD, respectively. This indicates that modification of the SI may be useful in determining the risk of distal upper extremity injury associated with a multi-task job.

Job Level Risk Assessment Using Task Level ACGIH Hand Activity Level TLV Scores: A Pilot Study

Existing upper extremity musculoskeletal disorder analytical tools are primarily intended for single or mono-task jobs. However, many jobs contain more than 1 task and some include job rotation. This case/control study investigates methods of modifying an existing tool, the American Conference of Governmental Industrial Hygienists (ACGIH) Hand Activity Level (HAL) Threshold Limit Value (TLV), to assess the upper extremity risk of multi-task jobs. Various methods of combining the task differences and ratios into a job level assessment were explored. Two methods returned significant odds ratios, (p < .05) of 18.0 (95% CI 1.8-172) and 12.0 (95% CI 1.2-120). These results indicate that a modified ACGIH HAL TLV may provide insight into the work-related risk of multi-task jobs. Further research is needed to optimize this process.

Study protocol title: a prospective cohort study of low back pain

BACKGROUND

Few prospective cohort studies of workplace low back pain (LBP) with quantified job physical exposure have been performed. There are few prospective epidemiological studies for LBP occupational risk factors and reported data generally have few adjustments for many personal and psychosocial factors.

METHODS/DESIGN

A multi-center prospective cohort study has been incepted to quantify risk factors for LBP and potentially develop improved methods for designing and analyzing jobs. Due to the subjectivity of LBP, six measures of LBP are captured: 1) any LBP, 2) LBP ≥ 5/10 pain rating, 3) LBP with medication use, 4) LBP with healthcare provider visits, 5) LBP necessitating modified work duties and 6) LBP with lost work time. Workers have thus far been enrolled from 30 different employment settings in 4 diverse US states and performed widely varying work. At baseline, workers undergo laptop-administered questionnaires, structured interviews, and two standardized physical examinations to ascertain demographics, medical history, psychosocial factors, hobbies and physical activities, and current musculoskeletal disorders. All workers' jobs are individually measured for physical factors and are videotaped. Workers are followed monthly for the development of low back pain. Changes in jobs necessitate re-measure and re-videotaping of job physical factors. The lifetime cumulative incidence of low back pain will also include those with a past history of low back pain. Incident cases will exclude prevalent cases at baseline. Statistical methods planned include survival analyses and logistic regression.

DISCUSSION

Data analysis of a prospective cohort study of low back pain is underway and has successfully enrolled over 800 workers to date.

The WISTAH hand study: a prospective cohort study of distal upper extremity musculoskeletal disorders

Background

Few prospective cohort studies of distal upper extremity musculoskeletal disorders have been performed. Past studies have provided somewhat conflicting evidence for occupational risk factors and have largely reported data without adjustments for many personal and psychosocial factors.

Methods/design

A multi-center prospective cohort study was incepted to quantify risk factors for distal upper extremity musculoskeletal disorders and potentially develop improved methods for analyzing jobs. Disorders to analyze included carpal tunnel syndrome, lateral epicondylalgia, medial epicondylalgia, trigger digit, deQuervain’s stenosing tenosynovitis and other tendinoses. Workers have thus far been enrolled from 17 different employment settings in 3 diverse US states and performed widely varying work. At baseline, workers undergo laptop administered questionnaires, structured interviews, two standardized physical examinations and nerve conduction studies to ascertain demographic, medical history, psychosocial factors and current musculoskeletal disorders. All workers’ jobs are individually measured for physical factors and are videotaped. Workers are followed monthly for the development of musculoskeletal disorders. Repeat nerve conduction studies are performed for those with symptoms of tingling and numbness in the prior six months. Changes in jobs necessitate re-measure and re-videotaping of job physical factors. Case definitions have been established. Point prevalence of carpal tunnel syndrome is a combination of paraesthesias in at least two median nerve-served digits plus an abnormal nerve conduction study at baseline. The lifetime cumulative incidence of carpal tunnel syndrome will also include those with a past history of carpal tunnel syndrome. Incident cases will exclude those with either a past history or prevalent cases at baseline. Statistical methods planned include survival analyses and logistic regression.

Discussion

A prospective cohort study of distal upper extremity musculoskeletal disorders is underway and has successfully enrolled over 1,000 workers to date.

Progress in vibrotactile threshold evaluation techniques: a review

Vibrotactile threshold (VT) testing has been used for nearly a century to investigate activation of human somatosensory pathways. This use of vibrotactile stimuli provides a versatile tool for detecting peripheral neuropathies, and has been broadly used for investigation of carpal tunnel syndrome. New applications include investigation of drug-induced neuropathies and diabetes-related neuropathies. As a feedback device, the vibrotactile stimuli could be used as an information delivery system for rehabilitative feedback devices for upper limb musculoskeletal disorders or as information channels for the visually impaired. This review provides a comprehensive review of the advancement in VT measurement techniques over time and a comparison of these techniques in terms of various hardware features used and the testing protocols implemented. The advantages and limitations of these methods have been discussed along with specific recommendations for their implementation and suggestions for incorporation into clinical practice.

Development of a carpal tunnel syndrome screening method using structured interviews and vibrotactile testing

Carpal tunnel syndrome (CTS) is a debilitating and expensive health problem. An inexpensive screening method that would differentiate between people who do not have CTS and those that may have CTS would be useful. The screening methodology investigated here had two phases: a structured interview and provocative vibrotactile testing (VT). The control group (n = 36) was composed of asymptomatic college students and faculty, the case group was composed of patients currently visiting an occupational medicine clinic for symptoms consistent with CTS. The case group was subdivided into positive and negative for nerve conduction latency, NCL+ (n = 21) and NCL- (n = 13), respectively. Using a scored, structured interview, 33 of the controls and none of the symptomatic cases were identified as non-CTS. The results from the provocative flexion VT indicated that if the difference between the age corrected baseline and the threshold at 15 minutes is 15 microm or more, the subject was likely to be NCL+ (odds ratio 12.6, 95% CI 3.8 to 41.8). Further research may improve this screening methodology to not only determine whether or not a person has CTS, but also to determine the level of median nerve impingement or damage.

Low back pain among residential carpenters: ergonomic evaluation using OWAS and 2D compression estimation

Occupational low back pain (LBP) remains a leading safety and health challenge. This cross-sectional investigation measured the prevalence of LBP in residential carpenters and investigated ergonomic risk factors. Ninety-four carpenters were investigated for LBP presence and associated risk factors. Ten representative job-tasks were evaluated using the Ovako Working Posture Analysis System (OWAS) and ErgoMaster 2D software to measure elements of posture, stress, and risk. Job-tasks were found to differ significantly for total lumbar compression and shear at peak loading (p < .001), ranging from 2 956 to 8 606 N and 802 to 1 974 N respectively. OWAS indicated that slight risk for injury was found in 10 job-tasks while distinct risk was found in 7 of the 10 job-tasks. Seven of the 10 job-tasks exceeded the National Institute for Occupational Safety and Health (NIOSH) action limit of 3 400 N for low back loading. The point prevalence for LBP was 14% while the annual prevalence was 38%.

Evaluation and quantification of manual materials handling risk factors

This study investigated the ability of the Revised NIOSH Lifting Equation (RNLE) to measure the risk of low back injury as verified by employee health outcomes. In addition, several basic risk factors and combinations of risk factors presumed related to low back disorders were explored. The RNLE was modified to allow analysis of one-handed and two-handed, asymmetric lifts. Predictive performance was not changed. Simplifying the RNLE by removing several variables did not significantly reduce the RNLE's predictive performance. These modifications to the RNLE show promise for increasing both the usability and utility of the RNLE.

Fatal injuries to teenage construction workers in the US

BACKGROUND

The construction industry is second only to agriculture in the annual number of fatal injuries in workers less than 18 years of age. We examined fatal injury reports for youth and adult workers to determine risk factors for injury and applicability of existing child labor regulations.

METHODS

The US Occupational Safety & Health Administration (OSHA) investigation data for fatal work injuries from 1984 through 1998 were reviewed with respect to type of event, employer characteristics, and apparent violations of existing child labor laws under the Fair Labor Standards Act (FLSA). We also examined whether the employer met exemption criteria for federal enforcement of child labor or OSHA regulations.

RESULTS

The fatality rate for teenage construction workers age 19 and younger was 12.1 per 100,000 per year, slightly less than for adult workers. Teenage workers who were fatally injured were more likely than adults to have been employed at non-union construction firms (odds ratio (OR) = 4.96, P < 0.05), firms with fewer than 11 employees (OR = 1.72, P < 0.05), and their employers were more likely to have been cited by OSHA for safety violations (OR = 1.66, P < 0.05) than for firms which were investigated because of a fatality in an adult worker. Fatalities in teenagers were more likely to occur in special construction trades such as roofing. Among fatalities in workers less than 18 years of age, approximately one-half (49%) of the 76 fatal injuries were in apparent violation of existing child labor regulations. We estimated that in 41 of the 76 cases (54%) the employer's gross annual income exceeded the $500,000 threshold for federal enforcement of child labor laws. Only 28 of 76 cases (37%) were at construction firms with 11 or more employees, which are subject to routine OSHA inspections.

CONCLUSIONS

Fatal injuries in teenage construction workers differed from those in adults in that they were more likely to be at small, non-union firms of which a substantial proportion were exempt from federal enforcement of child labor laws and from routine OSHA inspections. Safety programs for young construction workers should include small, non-union construction firms and those in special construction trades such as roofing. We did not identify specific areas for new regulation but the number of fatalities reviewed was small.

Fatal injuries in the United States involving respirators, 1984-1995

There is little published information concerning the epidemiology of fatal injuries involving respiratory protection. We compiled a case series from U.S. Occupational Safety and Health Administration investigation reports from 1984 through 1995. For the 12-year period there were 41 incidents resulting in 45 deaths due to asphyxiation or chemical poisoning while wearing a respirator. There were 23 deaths related to airline respirators, 17 deaths involving use of negative pressure (air purifying) respirators, and 5 deaths involving self-contained breathing apparatus. Among the 23 deaths involving airline respirators, 15 were associated with compatible connection couplings for breathable air and inert gases. Three workers with beards died who wore tight-fitting respirators in an atmosphere that was immediately dangerous to life and health. Most of the fatalities involved regulatory and procedural violations, and would have been prevented by proper training and compliance with existing regulations. The information concerning the victims was limited but it did not appear that medical screening would have prevented any of the deaths.

Comparison of ergonomic risk assessment outputs from Rapid Upper Limb Assessment and the Strain Index for tasks in automotive assembly plants

This paper compares the ergonomic risk assessment of a task for the upper extremities as determined by Rapid Upper Extremity Assessment (RULA) and the Strain Index (SI). The ergonomic risk to the upper extremities of 244 automotive assembly plant tasks were evaluated using RULA and SI. The outcomes of each tool were compared for each task. Results from this study provide practical insight into the methods used in each tool. This study compared only the ergonomic risk outputs from each tool; it does not pursue the question of which tool best predicts injury. The kappa score was 0.11, indicating little agreement between the outputs of the two tools. This is supported by the lack of monotonicity with a gamma score of 0.1. These results indicate that the risk assessment outcome of these two ergonomic assessment tools for the upper extremities do not agree.

Impact of the OSHA trench and excavation standard on fatal injury in the construction industry

In 1989 the US Occupational Safety & Health Administration revised the excavation and trenching standard. We examined fatal injuries from trench cave-in in the construction industry for five year periods before and after the revision in the 47 US states for which data were available for both periods. There was a 2-fold decline in the rate of fatal injury after revision of the standard, which substantially exceeded the decline in other causes of fatal injury in the construction industry during the same period. The decline was somewhat greater in large business firms but was evident in construction firms of all size classes. The fatality rate from trench cave-in in union construction workers was approximately half that of nonunion workers, but we were unable to determine whether this was best explained by union status, employment of union workers at larger construction firms, or both. This study provides evidence for the effectiveness of OSHA regulation in preventing fatal work injury.