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

Risk assessments using the Strain Index and the TLV for HAL, Part I: Task and multi-task job exposure classifications

BACKGROUND

The Strain Index (SI) and the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value for Hand Activity Level (TLV for HAL) use different constituent variables to quantify task physical exposures. Similarly, time-weighted-average (TWA), Peak, and Typical exposure techniques to quantify physical exposure from multi-task jobs make different assumptions about each task's contribution to the whole job exposure. Thus, task and job physical exposure classifications differ depending upon which model and technique are used for quantification. This study examines exposure classification agreement, disagreement, correlation, and magnitude of classification differences between these models and techniques.

METHODS

Data from 710 multi-task job workers performing 3,647 tasks were analyzed using the SI and TLV for HAL models, as well as with the TWA, Typical and Peak job exposure techniques. Physical exposures were classified as low, medium, and high using each model's recommended, or a priori limits. Exposure classification agreement and disagreement between models (SI, TLV for HAL) and between job exposure techniques (TWA, Typical, Peak) were described and analyzed.

RESULTS

Regardless of technique, the SI classified more tasks as high exposure than the TLV for HAL, and the TLV for HAL classified more tasks as low exposure. The models agreed on 48.5% of task classifications (kappa = 0.28) with 15.5% of disagreement between low and high exposure categories. Between-technique (i.e., TWA, Typical, Peak) agreement ranged from 61-93% (kappa: 0.16-0.92) depending on whether the SI or TLV for HAL was used.

CONCLUSIONS

There was disagreement between the SI and TLV for HAL and between the TWA, Typical and Peak techniques. Disagreement creates uncertainty for job design, job analysis, risk assessments, and developing interventions. Task exposure classifications from the SI and TLV for HAL might complement each other. However, TWA, Typical, and Peak job exposure techniques all have limitations. Part II of this article examines whether the observed differences between these models and techniques produce different exposure-response relationships for predicting prevalence of carpal tunnel syndrome.

Mechanical stress

This chapter discusses mechanical stressors that are believed to be associated with work-related musculoskeletal disorders. It starts with an introduction to work-related musculoskeletal disorders (particularly those with high incidences in workplaces, such as disorders of low back, neck/shoulder, hand/wrist, elbow, and knee) in high-risk industries, and those mechanical stressors (such as high forces, awkward postures, high repetitions, excessive contact stress, and harmful human vibrations) in workplaces that are responsible for these disorders. Quantification methods of these mechanical stressors are then discussed. Although various quantification methods such as self-report, observational technique, and direct measurement are discussed, details are focused on many of those well-published observational techniques used by practitioners to assess risk levels of these mechanical stressors in jobs. These methods can quantify job mechanical stressors and provide risk level indications that can be used by practitioners to facilitate their decision making. These methods can also be used to evaluate the improvements of ergonomics interventions by comparing the risk levels quantitatively before and after the interventions.

Association between stress at work and primary headache among nursing staff in Taiwan

BACKGROUND

Stress, one of the most commonly identified triggers for primary headache in the workplace, usually leads to inefficient work during attacks. Stress-related primary headaches in the nursing staff of hospitals have received little attention.

OBJECTIVE

To realize the association between stress and headache, and the means of coping with this kind of headache.

METHODS

A cross-sectional, hospital-based study using a semi-structured questionnaire was administered to 900 nursing staffers in a tertiary medical center in southern Taiwan. Thirty-two items, including basic information, headache- and stress-related questions, work satisfaction, and coping strategies were measured. Headache sufferers with either migraine or episodic tension headache (attacks <15 days per month) based on International Headache Society (IHS) criteria were enrolled for analysis. The Student's t-test, one-way analysis of variance (ANOVA), and chi-square test were used for statistical analysis.

RESULTS

Three hundred eighty-six out of 779 responders (49.6%) had experienced primary headaches in the previous year, and 374 (48.1%) had had episodic-type headaches (<15 days/month). A careful neurological interview of the latter group revealed that 222 (28.5%) had migraine, 104 (13.4%) had tension headache, 37 (4.8%) had mixed migraine and tension headache, and 11 (1.4%) had other causes of headache. There were no demographic differences between the sufferers and nonsufferers, although a statistically significant difference was noted in self-reported sources of stress (individual P values ranged from .021 to < .001). Headache sufferers had more stress at work than non-headache sufferers (P < .001). The youngest and least experienced of the nursing staff, the unmarried, and those with a lower level of education had a higher level of stress. The methods used to deal with headaches were sleep, taking medicine, taking a rest, visiting the doctor, and seeking psychological help. Nurses commonly used acetaminophen (panadol--500 mg) to relieve their pain.

CONCLUSION

These results indicate that stress at work is associated with primary headaches among nursing staff, and that nurses rarely seek help in the beginning. Therefore, nursing staff education aimed at ameliorating the stress and coping with the headaches, thus allowing the nurses to provide better patient care, may be warranted.