Assigning a value for metabolic rate is central to heat stress assessment. ISO 8996 describes a predictive method for walking based on the American College of Sports Medicine (ACSM) method and another generalized method based on average heart rate. In addition, the US Army uses the load carriage decision aid (LCDA) predictive equation to estimate metabolic rate. The purpose of this study was to assess the accuracy/bias and precision of the ISO heart rate method and the ACSM and LCDA equations. The laboratory database included metabolic rate, heart rate, treadmill speed, and grade during a progressive heat stress protocol. Treadmill speed and grade were set to represent one of three metabolic rates. Accuracy and precision were assessed with Bland-Altman plots. All three methods had good accuracy (low bias). For precision, the ISO heart rate method had a root mean square error (RMSE) of 34 W and 11% when adjusted for repeated measures. The RMSE for two equations was 20 W and 7%. Although the heart method had less accuracy, its application is more generalizable. The heart rate method should be used below the occupational exposure limit for heat stress to avoid a bias toward higher predicted values due to heat strain.

With the global nurse shortage, identifying nurse work environments that allow nurses to continue working is a common concern worldwide. This study examined whether a better nurse work environment (1) is associated with reducing nurses’ psychological distress; (2) reduces nurse resignations; (3) weakens the influence of psychological distress on their resignation through interaction effect; and (4) whether psychological distress increases nurse turnover. Multilevel logistic regression analyses were performed using data obtained in 2014 from 2,123 staff nurses from a prospective longitudinal survey project of Japanese hospitals. The nurse work environment was measured by the Practice Environment Scale of the Nursing Work Index (PES-NWI) consisting of five subscales and a composite, and psychological distress by K6. All the PES-NWI subscales and composite (ORs 0.679–0.834) were related to K6, significantly. Regarding nurse turnover, K6 had a consistent effect (ORs 1.834–1.937), and only subscale 2 of the PES-NWI had a direct effect (OR 0.754), but there was no effect due to the interaction term. That is, (1) and (4) were validated, (2) was partly validated, but (3) was not. As better work environment reduces K6 and a lower K6 decreases nurses’ resignation, high-level hospital managers need to continue improving the nurse work environment.

This cross-sectional study investigates the association between long working hours, short sleep duration, and mental health among Japanese physicians. We enrolled 232 Japanese physicians. We used the Brief Job Stress Questionnaire to assess high-stress status, and the Japanese version of the Center for Epidemiologic Studies Depression scale to assess depressive status. Daily sleep duration (DSD) and weekly working hours (WWHs) were collected using a self-administered questionnaire. Multivariable-adjusted logistic regression analysis was performed to examine the association of the combined categories of DSD and WWHs with high-stress and depressive status. Compared to physicians with WWHs <80 h and DSD ≥6 h, the multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of high-stress status for those with WWHs ≥80 and DSD ≥6, WWHs <80 and DSD <6, and WWHs ≥80 and DSD <6 were 2.76 (0.97–7.87), 3.36 (1.53–7.40), and 3.92 (1.52–10.14), respectively. The respective ORs (CIs) of depressive status were 1.82 (0.42–7.81), 4.03 (1.41–11.53), and 4.69 (1.33–16.62). The results showed that regardless of working long hours or not, physicians with DSD <6 h had significantly higher stress and depressive status, suggesting that not only regulating long working hours but also ensuring adequate sleep duration is important for preventing physicians’ mental health.

Firefighters risk heat strain during occupational tasks when exposed to extremely hot environmental conditions and performing high-intensity work. Relevant training scenarios are therefore essential. This study investigated the effect of a single simulated smoke dive and the following recovery phase on physiological and perceptual responses. Nineteen professional male firefighters (43 ± 8 yr) performed a 2-min stair walk and a15-min simulated smoke dive in a two-floor heat chamber (110°C to 272°C) (HEAT), followed by a 5-min stair walk outside the heat chamber. Heart rate (HR), gastrointestinal temperature (T_gi) and skin temperatures were registered continuously during the test. The T_gi increased significantly from the start (37.5 ± 0.3°C) to the end of HEAT (38.4 ± 0.4°C) and further increased after the heat exposure (39.6 ± 0.5°C). The HR also increased significantly from the start (92 ± 14 bpm) to the end of HEAT (185 ± 13 bpm) and increased after the heat exposure to a maximum of 190 ± 13 bpm. The simulated smoke dive induced high physiological strain on the firefighters, and the increase in T_gi and HR after the hot exposure must be considered during live fire events when repeated smoke dives are required.

The influence of night shift work on circadian heart-rate rhythm was examined in nurses engaged in shift work using a Holter electrocardiogram, continuously measured for two weeks, and cosine periodic regression analysis. We enrolled 11 nurses who were engaged in a two-shift system. The R² value in the cosine regression curve of heart-rate rhythm (concordance rate), indicating the concordance rate between the actual heart rate over 24 h and the cosine regression curve approximated by the least-squares procedure, was significantly lower in the night shift (0.40 ± 0.15) than in the day shift (0.66 ± 0.19; p<0.001). Moreover, the amplitude was significantly lower and the acrophase was significantly delayed in the night shift. Thus, the circadian heart-rate rhythm was disrupted by the night shift work. Although the heart-rate acrophase recovered during the day and two days after the night shift, the concordance rate and amplitude did not recover, indicating that the influence of night shift work on circadian heart-rate rhythm might persist even two days after the night shift. Based on these results, adequate clinical attention should be paid to how to spend the day and two days after the night shift to correct the circadian heart-rate rhythm disruption caused by night shift work.

Occupational exposure to manganese (Mn) primarily occurs through the inhalation of manganese-containing fumes and dust, with welding environments being significant sources of such exposure. Elevated levels of Mn in welding fumes can lead to a neurological syndrome known as manganism. A 28-yr-old male welder with 14 yr of experience, is presenting with complaints of forgetfulness, reasoning disorder, and decreased mental functions persisting for 10 yr. Three months ago, when he started working at the new workplace, he underwent employment screening conducted by the workplace physician. During this screening process, the physician identified a high whole blood Mn level of 25.9 µg/l. The diagnosis of manganism in this patient was established based on exposure to Mn and its compounds, high levels of Mn detected in the whole blood, hyperactive patellar reflexes observed during the physical examination, cranial Magnetic Resonance Imaging (MRI) findings consistent with manganism and complaints reported by the patient that are characteristic of manganism. In this report, the aim is to emphasize the significance of taking a comprehensive occupational history and to draw attention the potential health hazards associated with Mn and its compounds.

The study tested a brief intervention to stimulate and help supervisors reduce work-related interruptions among their employees, both at work and during leisure time. The core of the short-term intervention was a workplace analysis of work-related interruptions, which was fed back to supervisors in combination with a work redesign stimulation explaining why and how to reduce interruptions. Two intervention sessions, as one-on-one physical meetings, that lasted 1.5 h each and were 2 wk apart. The sample consisted of 20 managers and 89 employees. The non-experimental repeated measurement design comprised three questionnaire measurements of the 89 employees (two pre-measurements and one post-measurement). Repeated measure hierarchical linear models showed that the intervention significantly predicted reduced interruptions during work and work-related interruptions of leisure time. Although the intervention effect sizes were small, the current work design intervention with supervisors as mediating actors can reasonably contribute to occupational health prevention.