June M. Fisher

Objective stress factors, accidents, and absenteeism in transit operators : a theoretical framework and empirical evidence

The authors used observational job analysis as a conceptually based technique to measure stress factors unbiased by worker appraisal with 81 transit driving tasks on 27 transit lines. Stressor dimensions included work barriers that interfere with task performance due to poor technical-organizational design, time pressure, time binding (autonomy over time management), and monotonous conditions. Line-specific average stressor values were assigned to 308 transit operators who mainly worked the particular line. Logistic regression analyses showed associations for high work barriers and sickness absences (odds ratio [OR] = 3.8, p = .05). There were elevated risks for work accidents for high time pressure operators (OR = 4.0, p = .04) and for the medium time-binding group (OR = 3.3, p = .04) and significant (alpha = .20) unadjusted interaction terms for barriers and time pressure in predicting accidents and absences, and barriers and time binding in predicting absences. Findings suggest guaranteed rest breaks and flexible timing for accident prevention and removal of work barriers for reducing absenteeism.

Objective measurement of occupational stress factors--an example with San Francisco urban transit operators.

Eighty-one observational work analyses were conducted to measure stressors independently of worker appraisal in the San Francisco transit system. On the basis of action regulation theory, stress factors were defined as hindrances for task performance due to poor work organization or technological design. Stressors included (a) work barriers, defined as obstacles that cause extra work or unsafe behavior; (b) time pressure; (c) monotonous conditions; and (d) time binding, defined as control over timing. Reliability, measured as interrater agreement, ranged between 80 and 97%, with kappas of .46-.70. Validity analyses were done with 71 transit operators who participated in the observations and 177 operators who were assigned mean line-specific observational stressor measures. High odds ratios (ORs) were found for barriers and psychosomatic complaints (OR = 3.8, p = .00), time pressure and relaxation time needed after work (OR = 3.1, p = .05), and barriers and smoking to cope (OR = 3.8, p = .02). Using observational data in conjunction with self-report data can reduce confounding and improve interpretability of stress and health studies. Language: en

Physical Workload and Ergonomic Factors Associated With Prevalence of Back and Neck Pain in Urban Transit Operators

Study Design. Back and neck pain was studied crosssectionally in 1,449 urban transit drivers by linking medical data, self‐reported ergonomic factors, and company records on job history. Objectives. The goal was to examine the relation between physical workload, ergonomic factors, and the prevalence of back and neck pain. Summary of Background Data. Researchers, to date, have not found an independent effect of ergonomic factors on back and neck pain while accounting for the effects of past and current physical workload. Methods. Self‐reported ergonomic factors, vehicle type, physical workload (measured as duration of driving), height, weight, age, and gender were analyzed in relation to back and neck pain, using multivariable logistic regression models. Results. Physical workload showed a positive dose‐response relation with back and neck pain after controlling for vehicle type, height, weight, age, and gender. The odds ratio for 10 years of driving was 3.43. Additional adjustment for ergonomic factors decreased this odds ratio to 2.55. Six out of seven ergonomic factors were significantly related to the prevalence of back and neck pain after adjustment for age, gender, height, weight, and physical workload. Problems with adjusting the seat had the largest effect (odds ratio = 3.52). Women had back and neck pain twice as frequently as men. Conclusion. The results support the hypothesis of a causal role of physical workload for the development of back and neck pain. Ergonomic factors partially mediated the risk of back and neck pain associated with driving, suggesting a potential for prevention of back and neck pain by ergonomic redesign of transit vehicles. Elevated risks for back and neck pain for female drivers were not explained by anthropometric and ergonomic factors.

Sister-chromatid exchanges in lymphocytes of anatomy students exposed to formaldehyde-embalming solution

Sister-chromatid exchanges measured in the peripheral lymphocytes of 8 non-smoking persons after exposure to formaldehyde-embalming solution during a 10-week anatomy class showed a small (P = 0.02) average increase when compared with samples obtained from the same individuals immediately before exposure began. Breathing-zone air samples collected during dissection procedures showed a mean concentration of 1.2 ppm (1.5 mg/m3) formaldehyde.

Alcohol, stress-related factors, and short-term absenteeism among urban transit operators.

Transit operators, relative to workers in many other occupations, experience high levels of work-related stress, as documented through neuroendocrine elevations on the job vis-à-vis resting states (J Occup Health Psychol. 1998;3:122–129). Previous research suggests that self-reported job stress is associated with higher levels of alcohol consumption among transit operators (Alcohol Clin Exp Res. 2000;24:1011–1019) and with absenteeism (Working Environment for Local Public Transport Personnel, Stockholm: Swedish Work Environmental Fund, 1982; Work Stress. 1990;4:83–89). The purpose of this study was to examine the interrelationships between alcohol use, stress-related factors (stressful life events, job stressors, and burnout), and short-term absenteeism among a multiethnic cohort of urban transit operators. Self-reported measures of alcohol, stress-related factors, and short-term absenteeism were obtained from a sample (n=1,446) of San Francisco municipal transit operators who participated in the 1993–1995 Municipal Railway Health and Safety Study. Multivariate logistic regression analyses showed that absenteeism among drinkers was associated with risk for alcohol dependence [odds ratio (OR)=2.46, heavy drinking (OR=1.87), alcohol0related harm (OR=2.17), increased drinking since, becoming a transit operator (OR=1.74), and having any problem drinking indicator (OR=1.72). The association between absenteeism and stress-related factors varied by gender and drinking status. Final multivariate models among drinkers indicated that among males, problem drinking (OR=1.82), stressful life events (OR=1.62), and job burnout (OR=1.22) were independently associated with elevated odds of absenteeism. Among female drinkers, only stressful life events (OR=5.17) was significantly associated with elevated odds of absenteeism. Findings suggest that workplace interventions that address both individual and environmental stressors are most likely to have a positive impact on health-related outcomes, including problem drinking, thereby reducing absenteeism.

Hypertension and years of driving in transit vehicle operators

In this study, data from transit vehicle operators of the San Francisco Municipal Railway (Muni), and a control group of individuals newly hired but not yet working as operators, were used to investigate prevalence of hypertension as a function of exposure to bus driving (years of driving), controlling for alcohol consumption and body mass index. Data were collected from transit vehicle operators in the course of their regular biennial examination during the period November 1983 to October 1985. Groups working as operators fewer than 10 years (n =1137), from 10 to 20 years (n =493), and more than 20 years (n =196) were compared to each other and to a group of individuals with no prior exposure, but who were given a medical examination just before beginning their jobs as transit vehicle operators (n = 226). For hypertension (defined as systolic blood pressure ≤ 140, or diastolic blood pressure ≥90, or taking hypertension medication), the prevalence, adjusted for age, race, and gender, increased in a stepwise fashion from 28.8 percent in the group with no exposure to 38.9 percent in the group of drivers with more than 20 years on the job. A similar pattern was found for moderate to severe hypertension (systolic blood pressure ≤ 160, or diastolic blood pressure ≥95, or hypertension medication). These patterns were diminished, but not eliminated, when body mass index and alcohol consumption were considered. Higher rates of separation from employment for hypertensive operators suggested that the effect of years of employment may be underestimated by this cross-sectional comparison. Prolonged exposure to operating a transit vehicle may be associated with increased hypertension; increased alcohol consumption and body mass index with increased years of driving may account for at least some of the increased hypertension.

Burnout and alcohol problems among urban transit operators in San Francisco

Although occupational burnout has been linked with numerous psychosomatic symptoms and mental health problems, few studies have examined the association between burnout and substance use. This study assessed the contribution of burnout (Emotional Exhaustion--Maslach Burnout Inventory) to the risk of alcohol dependence and alcohol-related harm among a sample of urban transit operators. The study population consisted of 993 current drinkers who participated in the 1993-1995 San Francisco Muni Health and Safety Study. A series of multivariate logistic regression models were developed to analyze the association between burnout and risk of alcohol problems after adjustment for seniority, sociodemographic factors, and mean daily ounces of ethanol. The results indicate that burnout is associated with elevated risk of alcohol dependence (odds ratio [OR] = 1.03; 95% confidence interval [CI] = 1.01, 1.06). The association between burnout and alcohol-related harm, however, was attenuated. These findings suggest that transit operators with higher levels of burnout may be at increased risk for alcohol problems, particularly alcohol dependence. The temporal relationship between the development of burnout and the onset of alcohol problems among occupational cohorts warrants further investigation.

Attributable risk of alcohol and other drugs for crashes in the transit industry

Objective: To estimate the impact of employee alcohol and drug use on crashes in the transit industry from 1995–2000. Design: Secondary analysis of federally mandated post crash and random alcohol and drug testing results. Setting: The US transit industry. Subjects: Transit industry employees. Main outcome measures: Relative risk (RR), population attributable risk (PAR), and population attributable risk percentage (PAR%). Results: For alcohol testing, the estimated PAR% ranged from 0.02% (1999) to 0.03% (1995). For drug testing, the estimated PAR% ranged from 0.38% (1998) to 0.67% (1997). Based on these calculations, the estimated number of crashes per 1000 crashes attributable to alcohol was less than one during 1995–2000, and the number attributable to drugs ranged from about four to about six. The number of crashes attributable to either alcohol or drugs did not vary greatly from 1995–2000. Estimated rates of crashes attributable to alcohol or drugs were substantially lower in 1995, the first year of testing, than had been projected based on previous estimates, and did not show substantial change from 1995–2000. Conclusions: Approaches to transit safety based on reducing employee use of alcohol and other drugs have modest potential for reducing number of fatalities, injuries, and crashes.

Prevalence of hypertension in bus drivers

1. To test whether prevalence of hypertension was higher among these bus drivers than among employed individuals in general, drivers were compared to three groups: individuals from both a national and local health survey and individuals undergoing baseline health exams prior to employment as bus drivers. 2. After adjustment for age and race, hypertension rates for bus drivers were significantly greater than rates for the three comparison groups. 3. These findings support previous results from international studies of bus drivers suggesting that exposure to the occupation of driving a bus may carry increased health risk.

Traffic volume and collisions involving transit and nontransit vehicles

This study reports an analysis of collisions occurring between public transit vehicles operated by the San Francisco Municipal Railway System (Muni), the public transit agency for the City of San Francisco, and nontransit vehicles. The analysis, focusing on weekday collisions during 1987, demonstrated a strong association between hourly transit collisions rates and hourly traffic volume. The collision rate varied from 0.01 per 1,000 Muni vehicle-hours of operation during the interval 5 A.M. to 6 A.M., a time of very low traffic volume, to 0.93 (approximately 1 collision per 1,000 Muni vehicle-hours of operation) during the interval 5 P.M. to 6 P.M., a time of very high traffic volume. Using a power function to predict either the total number of collisions, or the rate of collisions per 1,000 Muni vehicle-hours, almost 90% of total variation was accounted for by traffic volume. A very similar pattern was found for collisions judged either avoidable or unavoidable. A peak in the collision rate between 2 A.M. and 3 A.M. could not be accounted for by traffic volume alone. That peak occurred in the one-hour interval following the 2 A.M. closing of bars in San Francisco, and was composed entirely of a sharp increase in unavoidable collisions. Increasing traffic volume appeared to operate through two mechanisms: (i) an increase in the number of opportunities for a collision, defined as a quantity proportional to the product of the number of Muni and non-Muni vehicles; (ii) an increase in the probability of a collision occurring between any given pair of vehicles.