Very Long (> 48 hours) Shifts and Cardiovascular Strain in Firefighters: a Theoretical Framework

Working Hours, Shift, and Remote Work by Industry and Occupation in U.S. Full-time Workers

BACKGROUND

This study examines working hours, shift work, and remote work patterns by occupation and industry among U.S. full-time workers, along with the association between working and sleeping hours.

METHODS

Utilizing data from 2011 to 2020 American Time Use Survey, this national household survey examines how individuals aged 15 years or older in the United States spend their time within a 24-hour period.

FINDINGS

In 2011 to 2019, U.S. full-time workers averaged 8.1 hours of work and 7.8 hours spent sleep on workdays, increasing to 9.6 hours on non-workdays. Among all occupations, Emergency medical technicians and paramedics had the longest average working hours (10.4 hours). Protective services occupations had the highest percentage (41.7%) of workers reporting often working shifts other than daytime. Among all industries, truck transportation industry had the longest average working hours (9.2). Food services and drinking places industries had the highest percentage (28.6%) of workers reporting often working shifts other than daytime. Working hours showed a negative association with sleeping hours. In 2020, 34.0% of full-time workers reported remote work due to COVID-19, with the largest percentage (72.3%) occurring in business and financial operations.

CONCLUSIONS

The study findings offer essential benchmarks for comparing working hours and schedules across diverse occupations and industries. These insights empower occupational health practitioners to advocate for prevention measures, addressing health concerns arising from prolonged working hours and shift work.

The Cyclical Battle of Insomnia and Mental Health Impairment in Firefighters: A Narrative Review

The occupational requirements of full-time non-administrative firefighters include shift-work schedules and chronic exposure to alerting emergency alarms, hazardous working conditions, and psychologically traumatic events that they must attend and respond to. These compiling and enduring aspects of the career increase the firefighter's risk for insomnia and mental health conditions compared to the general population. Poor sleep quality and mental health impairments are known to coincide with and contribute to the symptom severity of one another. Thus, it is important to determine approaches that may improve sleep and/or mental health specifically for firefighters, as their occupation varies in many aspects from any other occupation. This review will discuss symptoms of insomnia and mental health conditions such as PTSD, anxiety, depression, substance abuse, and suicide in firefighters. The influencing factors of sleep and mental health will be examined including anxiety sensitivity, emotional regulation, and distress tolerance. Current sleep and mental health interventions specific to full-time firefighters are limited in number; however, the existing experimental studies will be outlined. Lastly, this review will provide support for exploring exercise as a possible intervention that may benefit the sleep and mental health of this population.

Comparing actigraphy and diary to measure daily and average sleep in firefighters: a Bland-Altman analysis

STUDY OBJECTIVES

This study sought to examine the relationship between actigraphy and the Consensus Sleep Diary to contribute information on their concurrent validity in a sample of career firefighters.

METHODS

Sixty firefighters were recruited from a large, urban fire department in the southwest United States that utilizes a fire-based emergency medical services system and a 5/6 shift schedule. A total of 329 differences were recorded during participants' 6-day between-shift recovery period. Data was collected utilizing the two most common forms of sleep analysis in an outpatient setting, wrist actigraphy (Actiwatch-2) and the Consensus Sleep Diary. Nine major sleep indices were computed: wake time after sleep onset, total sleep time, sleep onset latency, sleep offset, in-bed time, lights-off time, out-of-bed time, wake time, and sleep efficiency.

RESULTS

Firefighters overestimated sleep efficiency and underestimated wake after sleep onset by values that were greater than the American Academy of Sleep Medicine a priori clinical significance thresholds. All indices showed very broad limits of agreement. For example, the 95% confidence interval for diary and actigraphic total sleep time estimates fell within a 4.7-hour range.

CONCLUSIONS

Firefighters receiving recovery sleep between tours demonstrated significantly large disagreements between their daily self-reported sleep and measured actigraphic sleep. Sleep findings from actigraphic and Consensus Sleep Diary sleep assessments in this population should be interpreted cautiously until each method is compared against other reliable sleep analysis methods. Currently it is unclear if clinicians are using properly validated tools when diagnosing shift work disorder or other sleep disorders in firefighters.

CITATION

Marmis R, McGoldrick-Ruth L, Kelly MR, Haynes PL. Comparing actigraphy and diary to measure daily and average sleep in firefighters: a Bland-Altman analysis. J Clin Sleep Med. 2024;20(4):497-503.

Synergistic interaction between long shifts and short rest periods on depression in shift workers: A cross-sectional study from Korea

BACKGROUND

Long shifts and short rest periods (SRP) between shifts are important factors that greatly affect shift workers' health. However, reports on the psychological effects of shift work, such as depression, have been inconsistent. Therefore, this study aimed to investigate the combined effect of long shifts and SRP on depression in shift workers.

METHODS

This cross-sectional study included 3295 shift workers in the sixth Korean Working Conditions Survey. The relative excess risk due to interaction (RERI) was computed to estimate the combined effect of long shifts and SRP on depression.

RESULTS

Depression in shift workers was not significantly associated with long shifts or SRP after adjustment, but the risk was significantly increased when exposed to both factors simultaneously (odds ratio 1.36, 95% confidence interval 1.03-1.79). The RERI between the two factors was statistically significant (p = 0.020), indicating a synergistic interaction with depression. Sensitivity analysis by occupation showed a significant interaction in the combined group of office and service workers (p = 0.034).

CONCLUSIONS

Simultaneous exposure to SRP and long shifts should be avoided when planning shift work schedules or devising health policies for shift workers. Special consideration is needed for healthcare and service workers, who may be particularly vulnerable to negative health impacts due to shift work.

Adapting shift work schedules for sleep quality, sleep duration, and sleepiness in shift workers

BACKGROUND

Shift work is associated with insufficient sleep, which can compromise worker alertness with ultimate effects on occupational health and safety. Adapting shift work schedules may reduce adverse occupational outcomes.

OBJECTIVES

To assess the effects of shift schedule adaptation on sleep quality, sleep duration, and sleepiness among shift workers.

SEARCH METHODS

We searched CENTRAL, PubMed, Embase, and eight other databases on 13 December 2020, and again on 20 April 2022, applying no language restrictions.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and non-RCTs, including controlled before-after (CBA) trials, interrupted time series, and cross-over trials. Eligible trials evaluated any of the following shift schedule components. • Permanency of shifts • Regularity of shift changes • Direction of shift rotation • Speed of rotation • Shift duration • Timing of start of shifts • Distribution of shift schedule • Time off between shifts • Split shifts • Protected sleep • Worker participation We included studies that assessed sleep quality off-shift, sleep duration off-shift, or sleepiness during shifts.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the titles and abstracts of the records recovered by the search, read through the full-text articles of potentially eligible studies, and extracted data. We assessed the risk of bias of included studies using the Cochrane risk of bias tool, with specific additional domains for non-randomised and cluster-randomised studies. For all stages, we resolved any disagreements by consulting a third review author. We presented the results by study design and combined clinically homogeneous studies in meta-analyses using random-effects models. We assessed the certainty of the evidence with GRADE.

MAIN RESULTS

We included 11 studies with a total of 2125 participants. One study was conducted in a laboratory setting and was not considered for drawing conclusions on intervention effects. The included studies investigated different and often multiple changes to shift schedule, and were heterogeneous with respect to outcome measurement. Forward versus backward rotation Three CBA trials (561 participants) investigated the effects of forward rotation versus backward rotation. Only one CBA trial provided sufficient data for the quantitative analysis; it provided very low-certainty evidence that forward rotation compared with backward rotation did not affect sleep quality measured with the Basic Nordic Sleep Questionnaire (BNSQ; mean difference (MD) -0.20 points, 95% confidence interval (CI) -2.28 to 1.89; 62 participants) or sleep duration off-shift (MD -0.21 hours, 95% CI -3.29 to 2.88; 62 participants). However, there was also very low-certainty evidence that forward rotation reduced sleepiness during shifts measured with the BNSQ (MD -1.24 points, 95% CI -2.24 to -0.24; 62 participants). Faster versus slower rotation Two CBA trials and one non-randomised cross-over trial (341 participants) evaluated faster versus slower shift rotation. We were able to meta-analyse data from two studies. There was low-certainty evidence of no difference in sleep quality off-shift (standardised mean difference (SMD) -0.01, 95% CI -0.26 to 0.23) and very low-certainty evidence that faster shift rotation reduced sleep duration off-shift (SMD -0.26, 95% CI -0.51 to -0.01; 2 studies, 282 participants). The SMD for sleep duration translated to an MD of 0.38 hours' less sleep per day (95% CI -0.74 to -0.01). One study provided very low-certainty evidence that faster rotations decreased sleepiness during shifts measured with the BNSQ (MD -1.24 points, 95% CI -2.24 to -0.24; 62 participants). Limited shift duration (16 hours) versus unlimited shift duration Two RCTs (760 participants) evaluated 80-hour workweeks with maximum daily shift duration of 16 hours versus workweeks without any daily shift duration limits. There was low-certainty evidence that the 16-hour limit increased sleep duration off-shift (SMD 0.50, 95% CI 0.21 to 0.78; which translated to an MD of 0.73 hours' more sleep per day, 95% CI 0.30 to 1.13; 2 RCTs, 760 participants) and moderate-certainty evidence that the 16-hour limit reduced sleepiness during shifts, measured with the Karolinska Sleepiness Scale (SMD -0.29, 95% CI -0.44 to -0.14; which translated to an MD of 0.37 fewer points, 95% CI -0.55 to -0.17; 2 RCTs, 716 participants). Shorter versus longer shifts One RCT, one CBA trial, and one non-randomised cross-over trial (692 participants) evaluated shorter shift duration (eight to 10 hours) versus longer shift duration (two to three hours longer). There was very low-certainty evidence of no difference in sleep quality (SMD -0.23, 95% CI -0.61 to 0.15; which translated to an MD of 0.13 points lower on a scale of 1 to 5; 2 studies, 111 participants) or sleep duration off-shift (SMD 0.18, 95% CI -0.17 to 0.54; which translated to an MD of 0.26 hours' less sleep per day; 2 studies, 121 participants). The RCT and the non-randomised cross-over study found that shorter shifts reduced sleepiness during shifts, while the CBA study found no effect on sleepiness. More compressed versus more spread out shift schedules One RCT and one CBA trial (346 participants) evaluated more compressed versus more spread out shift schedules. The CBA trial provided very low-certainty evidence of no difference between the groups in sleep quality off-shift (MD 0.31 points, 95% CI -0.53 to 1.15) and sleep duration off-shift (MD 0.52 hours, 95% CI -0.52 to 1.56).

AUTHORS' CONCLUSIONS

Forward and faster rotation may reduce sleepiness during shifts, and may make no difference to sleep quality, but the evidence is very uncertain. Very low-certainty evidence indicated that sleep duration off-shift decreases with faster rotation. Low-certainty evidence indicated that on-duty workweeks with shift duration limited to 16 hours increases sleep duration, with moderate-certainty evidence for minimal reductions in sleepiness. Changes in shift duration and compression of workweeks had no effect on sleep or sleepiness, but the evidence was of very low-certainty. No evidence is available for other shift schedule changes. There is a need for more high-quality studies (preferably RCTs) for all shift schedule interventions to draw conclusions on the effects of shift schedule adaptations on sleep and sleepiness in shift workers.

The effect of extended shift work on autonomic function in occupational settings: A systematic review and meta-analysis

OBJECTIVE

To examine the effect of 24-h shift work on autonomic nervous system function via heart rate variability (HRV) methodologies.

METHODS

Electronic databases (indexed in either PubMed, MEDLINE, CINAHL, SPORTDiscus, or OpenDissertations) were searched from January 1964 to March 2023. A modified Downs and Black checklist was used for assessing methodological quality and the Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) approach was used to evaluate the quality of evidence. Study design, study population, study sample, shift work description, and assessment of HRV metrics and methods were extracted from each study.

FINDINGS

A total of 58 478 study articles were identified, of which 12 articles met inclusion criteria. Sample sizes varied from eight to 60 participants, with the ratio of low- to high-frequency HRV (LF/HF) as the most common frequency-domain variable reported. Of the nine included studies that observed LF/HF, three (33.3%) demonstrated a significant increase after 24-h shift work. Moreover, of the five studies that reported HF, two (40%) noted a significant decrease after 24-h shift work. When observing risk of bias, two (16.6%) studies were low quality, five (41.7%) were moderate quality, and five (41.7%) were high quality.

INTERPRETATION

There were inconsistent findings demonstrating an effect of 24-h shift work on autonomic function, with a suggested shift away from parasympathetic dominance. Discrepancies in HRV methodologies, such as the duration of recordings and hardware used for measurement, may have contributed to the disparity in findings. In addition, differences in roles and responsibilities across occupations may explain the incongruence in findings across studies.

Falls in older persons living alone: the role of individual, social and environmental factors

OBJECTIVE

To identify the prevalence and the risk factors of falling in older people (65+) living alone.

METHOD

This is a descriptive and transversal study which included 186 participants, aged 65+ living alone in community-dwelling.

RESULTS

The prevalence of falls was 80.1% (95% CI 74.1-85.8). Considering the last 3 months, the prevalence of falls reduced to 22.2% (95% CI 17.5-29.9) and the number of falls reported was 2.4 (sd = 2.1). Most falls were accidental (n = 74, 59.7%), followed by dizziness (n = 15, 12.1%) and almost 50% occurred in the morning (n = 53, 45.3%). Considering the local where the falls occurred, 70 (57.4%) were at home (36.1% inside and 21.3% outside), 41 on the street (33.6%) and only 11 (9.0%) in a public place (4.1% inside and 4.9% outside). After the fall, 30.9% of the participants changed daily life after an event.

CONCLUSIONS

Falls among older adults is a multifactorial problem that requires integrated and multiprofessional interventions. Older age, living alone in an urban area, with insufficient resources, reduced physical activity and a poor self-perception are factors associated with a higher risk of falling. Similarly, older people who have difficulty standing, sitting and rising from a chair, as well as being hypertensive and taking a high number of medications are associated with a high risk of falling. Future research should develop and emphasize more national studies to confirm these results.

The Wildland Firefighter Exposure and Health Effect (WFFEHE) Study: Rationale, Design, and Methods of a Repeated-Measures Study

The wildland firefighter exposure and health effect (WFFEHE) study was a 2-year repeated-measures study to investigate occupational exposures and acute and subacute health effects among wildland firefighters. This manuscript describes the study rationale, design, methods, limitations, challenges, and lessons learned. The WFFEHE cohort included fire personnel ages 18-57 from six federal wildland firefighting crews in Colorado and Idaho during the 2018 and 2019 fire seasons. All wildland firefighters employed by the recruited crews were invited to participate in the study at preseason and postseason study intervals. In 2019, one of the crews also participated in a 3-day midseason study interval where workplace exposures and pre/postshift measurements were collected while at a wildland fire incident. Study components assessed cardiovascular health, pulmonary function and inflammation, kidney function, workplace exposures, and noise-induced hearing loss. Measurements included self-reported risk factors and symptoms collected through questionnaires; serum and urine biomarkers of exposure, effect, and inflammation; pulmonary function; platelet function and arterial stiffness; and audiometric testing. Throughout the study, 154 wildland firefighters participated in at least one study interval, while 144 participated in two or more study interval. This study was completed by the Centers for Disease Control and Prevention's National Institute for Occupational Safety and Health through a collaborative effort with the U.S. Department of Agriculture Forest Service, Department of the Interior National Park Service, and Skidmore College. Conducting research in the wildfire environment came with many challenges including collecting study data with study participants with changing work schedules and conducting study protocols safely and operating laboratory equipment in remote field locations. Forthcoming WFFEHE study results will contribute to the scientific evidence regarding occupational risk factors and exposures that can impact wildland firefighter health over a season and across two wildland fire seasons. This research is anticipated to lead to the development of preventive measures and policies aimed at reducing risk for wildland firefighters and aid in identifying future research needs for the wildland fire community.

Mental Health of Canadian Firefighters: The Impact of Sleep

Volunteer and career firefighters are at risk of major depressive disorders, posttraumatic stress disorder (PTSD), alcohol use disorder, and other mental health disorders due to the demanding and unpredictable nature of their employment. The mental health risks are exacerbated by the need to work extended hours, night shifts, and/or rotating schedules, or the competing demands of other employment, especially in volunteer firefighters. The mental health disorders and risk factors interact with altered sleeping patterns. In the current study, we examined volunteer and career firefighters regarding the association between mental health and sleep, drawing from a national Canadian mental health survey of 1217 firefighters. Most (69%) of the firefighters reported less than ideal sleep quality and 21% screened positive for clinical insomnia, with no significant difference between volunteer and career subgroups. Firefighters with insomnia had higher odds ratios (OR) and frequencies for PTSD (OR = 4.98), generalized anxiety disorder (OR = 7.15), panic disorder (OR = 6.88), social phobia (OR = 4.98), and major depressive disorder (OR = 7.91), than firefighters without insomnia. The burden of sleep disorders and their association with mental health disorders suggests that sleep should be considered in health monitoring and self-management, environmental design, fire service work-organization policies, and health programming.

Low testosterone and cardiometabolic risks in a real-world study of US male firefighters

Low serum total testosterone (TT) is associated with increased cardiovascular risk and metabolic derangements, with fatty liver (FL) emerging as an additional cardiometabolic threat. We investigated the associations between TT and cardiometabolic (CM) health in 298 US male firefighters. Cross-sectional data from occupational health examination were analyzed. TT was categorized as low (< 264 ng/dL), borderline (264-399 ng/dL), and reference (400-916 ng/dL). Conventional CM risk factors were compared among TT categories, and between firefighters with and without FL. 81% of firefighters were obese/overweight; almost 40% had FL. In the low-TT group, only 3.1% had normal BMI, while 78.1% had FL. The low-TT group had a worse CM profile, independently of age and BMI, and a fourfold higher adjusted odds of having FL. FL was associated with lower TT, regardless of age, BMI and HbA1c. Having a FL, HbA1c ≥ 5.7% or triglycerides ≥ 150 mg/dL increased the odds for low-TT by 4.1, 2.7 and 6.6 times, respectively. These real-world data reveal strong associations between low-TT and CM risk factors and support a call for action towards screening for low-TT and FL, regardless of age, BMI or dysmetabolic conditions in firefighters. Recognizing cardiometabolic risks in firefighters provides an opportunity to lessen cardiovascular diseases burden.

A feasibility study of a WhatsApp-delivered Transtheoretical Model-based intervention to promote healthy eating habits for firefighters in Hong Kong: a cluster randomized controlled trial

BACKGROUND

Firefighters' health is often affected by a high prevalence of obesity and cardiovascular diseases, which are common risk factors for sudden cardiac death. The aim of this study is to investigate the feasibility of enhancing healthy eating habits in firefighters through an education programme.

METHODS

This will be a cluster randomized control trial study. The participants will be assigned randomly into either control (health promotion pamphlet) or intervention (health promotion pamphlet and education materials through WhatsApp) groups. Changes in healthy eating habits will be assessed by a self-administered questionnaire and anthropometric measurements at three different time points.

DISCUSSION

More education is required in order to improve firefighters' eating habits.

TRIAL REGISTRATION

ISRCTN registry identifier: Registered on 8 April 2019 ISRCTN95472464.

Effects of Wrist Cooling on Recovery From Exercise-Induced Heat Stress With Firefighting Personal Protective Equipment

OBJECTIVE

To determine the effects of wrist cooling on recovery from exercise-induced heat stress (EIHS) from wearing firefighting personal protective equipment (PPE) and self-contained breathing apparatus.

METHODS

Using a single-blind, counterbalanced, crossover-design, in 11 healthy men, we measured heart rate (HR), HR variability (HRV), core temperature (TCore), thermal strain (TS), and fatigue at rest, during 30-minute of exercise in PPE+SCBA, and during recovery while wearing a wrist cooling band (control[off] vs cool[on]).

RESULTS

No differences were observed between trials at baseline or during exercise, in HR, TCore, TS, or fatigue. Time to 50% and recovery were not different between trials. Upon recovery, TCore was lower, while HR, fatigue, HRV, and TS were relatively indifferent with cooling.

CONCLUSION

Wrist cooling after EIHS only modestly enhanced recovery, questioning its implementation during on-scene rehabilitation of firefighters.

The influence of cardiometabolic risk factors on cardiorespiratory fitness in volunteer Chilean firefighters

OBJECTIVES

Maximum oxygen consumption (VO2_max ) plays a fundamental role in firefighters' occupational activities due to the high intensity tasks they perform in their professional duties. In Chile, firefighters are volunteers (non-salary) and their lack of continuous and programmed physical activity may affect their physical fitness and health. The goal of this study was to determine the influence of anthropometric parameters and cardiometabolic risk (CMR) factors on the cardiorespiratory fitness (CRF) of volunteer Chilean firefighters.

METHODS

Seventy-six volunteer male firefighters (median [5-95 percentiles]) aged 27.5 years [26-56], body mass index (BMI) 27.7 kg m^-2 [19.9-35], and VO2_max 44 mL kg^-1 min^-1 [36-56]) participated in the study. The following variables were assessed: BMI, fat mass%, body density, waist circumference (WC), waist-to-hip ratio (WHR), blood pressure, blood glucose, and VO2_max .

RESULTS

In total, 68% of the samples were overweight or obese. A total of 36% presented abdominal obesity (WC ≥102 cm). High blood pressure (HBP) was observed in 25% of firefighters and high blood glucose was found in about 20%. The presence of abdominal obesity was the strongest predictor of VO2_max (OR = 12.35, 95% CI = 3.56-42.82, P < .001), followed by the WHR (OR = 11.5, 95% CI = 3.1-42.7, P < .001) and high blood glucose (OR = 2.87, 95% CI = 1.7-7.3, P = 0.019).

CONCLUSION

This study showed that abdominal obesity in firefighters was the strongest predictor of low CRF. In addition, CRF was associated with CMR factors, except for HBP.

Do night and around-the-clock firefighters' shift schedules induce deviation in tau from 24 hours of systolic and diastolic blood pressure circadian rhythms?

Systolic (S) and diastolic (D) blood pressures (BP) [SBP and DBP] are circadian rhythmic with period (τ) in healthy persons assumed to be maintained at 24.0h. We tested this assumption in a sample of 30 healthy career (mean >12 yrs) 30-to-46 yr-old male Caucasian French firefighters (FFs) categorized into three groups according to work schedule and duties: Group A - 12 FFs working 12h day, 12h night, and occasionally 24h shifts and whose primary duties are firefighting plus paramedical and road rescue services; Group B - 9 FFs working mostly 12h day and 12h night shifts and whose duties are answering incoming emergency calls and coordinating service vehicle dispatch from fire stations with Group A personnel; Group C - 9 day shift (09:00-17:00h) FFs charged with administrative tasks. SBP and DBP, both in winter and in summer studies of the same FFs, were sampled by ambulatory BP monitoring every 1h between 06:00-23:00h and every 2h between 23:01-05:59h, respectively, their approximate off-duty wake and sleep spans, for 7 consecutive days. Activity (wrist actigraphy) was also sampled at 1-min intervals. Prominent τ of each variable was derived by a power spectrum program written for unequal-interval time series data, and between-group differences in incidence of τ≠24h of FFs were assessed by chi square test. Circadian rhythm disruption (τ≠24h) of either the SBP or DBP rhythm occurred almost exclusively in night and 24h shift FFs of Group A and B, but almost never in day shift FFs of Group C, and it was not associated with altered τ from 24.0h of the circadian activity rhythm. In summer, occurrence of τ≠24 for FFs of Group A and B differed from that for FFs of Group C in SBP (p=0.042) and DBP (p=0.015); no such differences were found in winter (p>0.10). Overall, manifestation of prominent τ≠24h of SBP or DBP time series was greater in summer than winter, 27.6% versus 16.7%, when workload of Group B FFs, i.e. number of incoming emergency telephone calls, and of Group A FFs, i.e. number of dispatches for provision of emergency services, was, respectively, two and fourfold greater and number of 12h night shifts worked by Group B FFs and number of 24h shifts worked by Group A FFs was, respectively, 92% and 25% greater. FFs of the three groups exhibited no winter-summer difference in τ≠24h of SBP or SDP; however, τ≠24h of DBP in Group B FFs was more frequent in summer than winter (p=0.046). Sleep/wake cycle disruption, sleep deprivation, emotional and physical stress, artificial light-at-night, and altered nutrient timings are hypothesized causes of τ≠24h for BP rhythms of affected Groups A and B FFs, but with unknown future health effects.

One-year weight change and long-term sickness absence in professional firefighters

BACKGROUND

Little is known about the association between weight change (particularly moderate weight loss, 5-10% in initial weight) and long-term sickness absence (LSA) in working populations.

METHODS

Three hundred and forty professional firefighters reported their current and past (1 year ago) weights in a cross-sectional survey, along with their LSA experience due to a severe accident, injury, or illness during the previous 12 months.

RESULTS

The prevalence of LSA was 14.7%. In the non-smoking male firefighters, the prevalence of LSA was 3.4% in those with moderate weight loss over the past year; 13.3% in those who maintained their weight; and 21.7% in those who gained their weight moderately: gamma coefficient, 0.44 (95%CI: 0.05, 0.66). The linear association remained significant after further controlling for age and alcohol consumption. And it was similar across the adiposity strata (normal weight, overweight, and obesity) of the firefighters 1 year ago.

CONCLUSIONS

One-year weight loss was associated with decreased risk of LSA in professional firefighters.

Predictors of health-related quality of life among industrial workers: A descriptive correlational study

Assessment and evaluation of the health-related quality of life of industrial workers is an important research focus. This descriptive correlational study identifies the predictors of health-related quality of life using a random sampling of industrial workers (n = 640) from construction factories in Amman Governorate in Jordan using demographic characteristics, a health and work-related factors questionnaire, and the World Health Organization Quality of Life-Brief scale. Results showed that industrial workers had good physical health but a poor working environment. There was a statistically significant relationship between educational level, conflict between work and individual life and work and social life, working hours, and workload, and all domains of health-related quality of life. Overall, educational level was the main predictor for all domains of health-related quality of life. Such results confirm the need to develop appropriate interventions and strategies to improve workers' health-related quality of life. Furthermore, developing an integrated approach among policymakers, employers, and work organizations to enhance industrial workers' occupational health programs could be effective.

Ambulatory heart rate of professional taxi drivers while driving without their typical psychosocial work stressors: a pilot study

BACKGROUND

Few studies have examined ambulatory cardiovascular physiological parameters of taxi drivers while driving in relation to their occupational hazards. This study aims to investigate and quantify the impact of worksite physical hazards as a whole on ambulatory heart rate of professional taxi drivers while driving without their typical worksite psychosocial stressors.

METHODS

Ambulatory heart rate (HRdriving) of 13 non-smoking male taxi drivers (24 to 67 years old) while driving was continuously assessed on their 6-hour experimental on-road driving in Los Angeles. Percent maximum HR range (PMHRdriving) of the drivers while driving was estimated based on the individual HRdriving values and US adult population resting HR (HRrest) reference data. For analyses, the HRdriving and PMHRdriving data were split and averaged into 5-min segments. Five physical hazards inside taxi cabs were also monitored while driving. Work stress and work hours on typical work days were self-reported.

RESULTS

The means of the ambulatory 5-min HRdriving and PMHRdriving values of the 13 drivers were 80.5 bpm (11.2 bpm higher than their mean HRrest) and 10.7 % (range, 5.7 to 19.9 %), respectively. The means were lower than the upper limits of ambulatory HR and PMHR for a sustainable 8-hour work (35 bpm above HRrest and 30 % PMHR), although 15-27 % of the 5-min HRdriving and PMHRdriving values of one driver were higher than the limits. The levels of the five physical hazards among the drivers were modest: temperature (26.4 ± 3.0 °C), relative humidity (40.7 ± 10.4 %), PM2.5 (21.5 ± 7.9 μg/m3), CO2 (1,267.1 ± 580.0 ppm) and noise (69.7 ± 3.0 dBA). The drivers worked, on average, 72 h per week and more than half of them reported that their job were often stressful.

CONCLUSIONS

The impact of physical worksite hazards alone on ambulatory HR of professional taxi drivers in Los Angeles generally appeared to be minor. Future ambulatory heart rate studies including both physical and psychosocial hazards of professional taxi drivers are warranted.

Globalization, Work, and Cardiovascular Disease

Cardiovascular disease (CVD), a global epidemic, is responsible for about 30% of all deaths worldwide. While mortality rates from CVD have been mostly declining in the advanced industrialized nations, CVD risk factors, including hypertension, obesity, and diabetes, have been on the increase everywhere. Researchers investigating the social causes of CVD have produced a robust body of evidence documenting the relationships between the work environment and CVD, including through the mechanisms of psychosocial work stressors. We review the empirical evidence linking work, psychosocial stressors, and CVD. These work stressors can produce chronic biologic arousal and promote unhealthy behaviors and thus, increased CVD risk. We offer a theoretical model that illustrates how economic globalization influences the labor market and work organization in high-income countries, which, in turn, exacerbates job characteristics, such as demands, low job control, effort-reward imbalance, job insecurity, and long work hours. There is also a growing interest in “upstream” factors among work stress researchers, including precarious employment, downsizing/restructuring, privatization, and lean production. We conclude with suggestions for future epidemiologic research on the role of work in the development of CVD, as well as policy recommendations for prevention of work-related CVD.

Twenty-four-hour work shifts, increased job demands, and elevated blood pressure in professional firefighters

PURPOSE

To investigate whether working conditions (number of 24-h shifts, number of calls, sedentary work, job strain, effort-reward imbalance, and physical demands) are associated with elevated blood pressure and hypertension among professional firefighters.

METHODS

A total of 330 (321 males and 9 females) firefighters were chosen for this study among the Southern California firefighters who participated in a work and obesity project. Working conditions were measured with a firefighter-specific occupational health questionnaire. Blood pressure was clinically assessed, and hypertension was defined according to the contemporary standard classification.

RESULTS

About 11 % of the firefighters had hypertension. Fifty percent of the hypertensive firefighters (mostly mild hypertensive) had uncontrolled high blood pressure. Hypertension was more prevalent in male, older, and high-rank firefighters and firefighter who reported low numbers of daily calls. In male firefighters who were normotensive or hypertensive without taking anti-hypertensive medication, additional 24-h shifts in the past month increased the risk of elevated diastolic blood pressure (DBP) than those who reported a standard work schedule (eight to eleven 24-h shifts). Particularly, firefighters who reported sixteen 24-h shifts had 5.0 mmHg higher DBP (p < 0.01). Body mass index attenuated the association between number of shifts and blood pressure to some extent. Firefighters who reported "increased job demands over the past years" had 3.0 mmHg (p = 0.06) higher systolic blood pressure. Other working conditions were not associated with elevated blood pressure and hypertension.

CONCLUSIONS

Many additional 24-h shifts and increased job demands were risk factors for elevated blood pressure in male firefighters. Optimal collective and individual workload and improved hypertension management are warranted for enhancing the cardiovascular health of firefighters.

Factors related to heart rate variability among firefighters

OBJECTIVES

The aim of this study was to investigate factors associated with heart rate variability in firefighters working in a metropolitan city in South Korea.

METHODS

Self-administered questionnaires including Korean Occupational Stress Scale (KOSS) as well as surveys collecting socio-demographic characteristics and work-related factors were given to 962 firefighters. After exclusion for missing data, 645 firefighters were included, and analysis of covaiance adjusted for the general risk factors and job characteristics were used to assess the relationship between heart rate variability and associated factors.

RESULTS

SDNN and RMSSD and were decreased in the area of occupational climate of the group with high job stress (p = 0.027, p = 0.036). HF(ln) was decreased in the area of organizational system and occupational climate of the group with high stress that statistically significant level (p = 0.034, p = 0.043).

CONCLUSIONS

Occupational climate and organizational system are associated with reduction of heart rate variability. Preventive medical care plans for cardiovascular disease of firefighters through the analysis and evaluation of job stress factors are needed.

24-hour work shifts, sedentary work, and obesity in male firefighters

BACKGROUND

Little is known about the occupational risk factors for obesity in US firefighters.

METHODS

308 male California firefighters, who participated in a work and obesity project, were chosen. Working conditions were measured with a firefighter-specific occupational health questionnaire. Adiposity was clinically assessed using body mass index (BMI), waist circumference (WC), and body fat percent.

RESULTS

In a multivariate analysis, the prevalence of obesity by all measures was significantly higher (PRs = 3.69-6.03, P < 0.05) in the firefighters who reported seventeen to twenty-one shifts than those who reported eight to eleven shifts in the past month. Prolonged sedentary work was also a risk factor for obesity by BMI (PR = 4.18, P < 0.05). Furthermore, there was a linear dose-response relationship of obesity by BMI and WC with the number of 24-hr shifts and sedentary work.

CONCLUSIONS

Many additional 24-hr shifts and prolonged sedentary work substantially increased the risk for obesity in male firefighters. Am. J. Ind. Med. 59:486-500, 2016. © 2016 Wiley Periodicals, Inc.

Factors associated with health-related quality of life in Korean older workers

Objectives

The prevalence of aged individuals in the Korean workforce continues to increase. This research determined the health and working conditions of Korean older wage workers and confirmed the effects of factors on the health-related quality of life of Korean older workers.

Methods

Of the 25,534 persons surveyed in the fifth Korea National Health and Nutrition Examination Survey, 1368 older (>55 years of age) wage workers without missing variables were selected. Their general characteristics, health status (cardiovascular disease, musculoskeletal disease, and mental health), working conditions (type of occupation, employment status, full- or part-time work, weekly average working hours, and shift work), and health-related quality of life assessed by the EQ-5D questionnaire were examined.

Results

The mean values of the EQ-5D index of the male and female older workers were 0.956 ± 0.087 and 0.917 ± 0.124, respectively (p < 0.001). The factors that caused statistically significant differences in the EQ-5D index for all subjects were age, education, household income, cerebro-cardiovascular event, osteoarthritis, musculoskeletal pain, stress, occupation type, employment status, and working hours. In logistic regression analysis, the factors that associated with perceived problems in each EQ-5D dimensions were age, musculoskeletal pain, stress, diabetes, smoking, occupation type, employment status, and working hours.

Conclusions

To eventually raise the quality of life of older workers through health maintenance and management, it is necessary to manage related factors that include of musculoskeletal pain and diseases, stress, diabetes, smoking, occupation, employment status, and working hours.

Effects of high occupational physical activity, aging, and exercise on heart rate variability among male workers

Objectives

Effects of aging and leisure time physical activity (LPA) might influence the effect of occupational physical activity (OPA) on risk for cardiovascular disease (CVD). This study was conducted to determine whether OPA affects CVD after controlling the effects of LPA and other risk factors for CVD such as job stress.

Methods

Participants were 131 male Korean manual workers. Tests for heart rate variability (HRV) were conducted for five minutes in the morning at work. We defined OPA as the combined concept of relative heart rate ratio (RHR), evaluated using a heart rate monitor.

Results

Whereas high OPA was not related to any HRV items in the younger age group, high OPA was associated with an increased number of low-value cases among all HRV items in older workers. Exercise had beneficial effects only in the younger group. After controlling for exercise and other risk factors, the odds ratios of the root-mean square of the difference of successive normal R-R intervals (rMSSD) and high frequency band power (HF) among the older age and high OPA group compared with the younger age and low OPA group were 64.0 and 18.5, respectively. Social support and shift work were independent risk factors in HRV.

Conclusions

OPA in aging workers increases CVD risks. This study provides support for the need for protection of aging workers from physical work overload, and indicates the need for further study of optimal limits of OPA.

Non-accidental health impacts of wildfire smoke

Wildfires take a heavy toll on human health worldwide. Climate change may increase the risk of wildfire frequency. Therefore, in view of adapted preventive actions, there is an urgent need to further understand the health effects and public awareness of wildfires. We conducted a systematic review of non-accidental health impacts of wildfire and incorporated lessons learned from recent experiences. Based on the literature, various studies have established the relationship between one of the major components of wildfire, particulate matter (particles with diameter less than 10 µm (PM10) and less than 2.5 µm (PM2.5)) and cardiorespiratory symptoms in terms of Emergency Rooms visits and hospital admissions. Associations between wildfire emissions and various subclinical effects have also been established. However, few relationships between wildfire emissions and mortality have been observed. Certain segments of the population may be particularly vulnerable to smoke-related health risks. Among them, people with pre-existing cardiopulmonary conditions, the elderly, smokers and, for professional reasons, firefighters. Potential action mechanisms have been highlighted. Overall, more research is needed to better understand health impact of wildfire exposure.