Metabolic energy cost of workers in agriculture, construction, manufacturing, tourism, and transportation industries

Impact of work pace on cardiorespiratory outcomes, perceived effort and carried load in industrial workers: a randomised cross-over trial

OBJECTIVES

This study investigates the impact of different work paces on cardiorespiratory outcomes, perceived effort and carried load (CL) in industrial workers.

METHODS

A randomised cross-over trial was conducted at a mid-sized steel company. We included 12 healthy industrial workers (8 females, age: mean 44±SD 9 years, height: 1.70±0.08 m, body mass: 79.5±13.4 kg) with at least 6 months of working experience. All participants performed 5 min of piece work at 100% (P100), 115% (P115) and 130% (P130) of the company's internal target yielded in a randomised order, separated by 5 min familiarisation breaks. The primary outcome was energy expenditure (EE), calculated from a respiratory gas exchange using a metabolic analyser. Secondary outcomes were total ventilation, oxygen uptake, carbon dioxide release, respiratory exchange ratio, heart rate and rating of perceived effort (0-10). Furthermore, the metabolic equivalent and the CL were calculated. Data were analysed with repeated measure analyses of variance.

RESULTS

For EE, a large 'pace' effect with a small difference between P100 and P130 (165.9±33.4 vs 178.8±40.1 kcal/hour-1, p=0.008, standard mean difference, SMD=0.35) was revealed. Additionally, a large difference in CL between all paces (p<0.001, SMD≥1.10) was revealed. No adverse events occurred.

CONCLUSIONS

Cardiorespiratory outcomes rise with increased work pace, but the practical relevance of these differences still needs to be specified. However, the CL will add up over time and may impact musculoskeletal health in the long term.

'Wait…, let me tell you, if I worked for a boss, I would be on sick leave': A Qualitative Study of Self-Employed Workers in Physically Demanding Jobs in the Netherlands

PURPOSE

The purpose of this study was to explore the perspectives of self-employed workers with a physically demanding job on work participation.

METHODS

We interviewed self-employed workers with a physically demanding job, using semi-structured interviews, which were audio recorded. The main topic addressed was the workers' health in relation with their work participation, work demands, and preventive measures. The interviews were transcribed verbatim and coded by three team members of the research team in several steps. We used the consolidated criteria for reporting qualitative research (COREQ) checklist to report our findings.

RESULTS

We interviewed 18 self-employed workers: 83% male, 49 years (SD 7), self-employed for 18 years (SD 9) and the majority (n = 14) worked in the construction sector. Thematic analysis revealed facilitators and barriers for work participation across three main themes: personal factors, work factors, and healthcare. Personal factors compassed sub-themes such as health and financial consequences. Work factors included sub-themes related to work demands and adaptations and healthcare encompassed sub-themes associated with work-related care and medication.

CONCLUSION

To our knowledge, this is the first qualitative study that investigated the perspectives of self-employed workers in physically demanding jobs regarding work participation. While most facilitators and barriers were consistent with those described in the literature for employees, certain factors, such as financial consequences of ceasing work, emerged important factors for work participation among self-employed workers.

Work-rest regimens for work in hot environments: A scoping review

BACKGROUND

To limit exposures to occupational heat stress, leading occupational health and safety organizations recommend work-rest regimens to prevent core temperature from exceeding 38°C or increasing by ≥1°C. This scoping review aims to map existing knowledge of the effects of work-rest regimens in hot environments and to propose recommendations for future research based on identified gaps.

METHODS

We performed a search of 10 databases to retrieve studies focused on work-rest regimens under hot conditions.

RESULTS

Forty-nine articles were included, of which 35 were experimental studies. Most studies were conducted in laboratory settings, in North America (71%), on healthy young adults, with 94% of the 642 participants being males. Most studies (66%) employed a protocol duration ≤240 min (222 ± 162 min, range: 37-660) and the time-weighted average wet-bulb globe temperature was 27 ± 4°C (range: 18-34). The work-rest regimens implemented were those proposed by the American Conference of Governmental and Industrial Hygiene (20%), National Institute of Occupational Safety and Health (11%), or the Australian Army (3%). The remaining studies (66%) did not mention how the work-rest regimens were derived. Most studies (89%) focused on physical tasks only. Most studies (94%) reported core temperature, whereas only 22% reported physical and/or mental performance outcomes, respectively. Of the 35 experimental studies included, 77% indicated that core temperature exceeded 38°C.

CONCLUSIONS

Although work-rest regimens are widely used, few studies have investigated their physiological effectiveness. These studies were mainly short in duration, involved mostly healthy young males, and rarely considered the effect of work-rest regimens beyond heat strain during physical exertion.

Chronic Kidney Disease Among Agricultural Workers in Taiwan: A Nationwide Population-Based Study

Introduction

Chronic kidney disease (CKD) in agricultural communities is a significant public health issue. We aimed to investigate the epidemiology of CKD among Taiwanese farmers and its association with outdoor heat exposure.

Methods

A nested case-control study was conducted on participants in the National Adult Health Examination (NAHE) from 2012 to 2018. The farming occupation was identified through National Health Insurance data. The primary outcomes of interest were the development of CKD, defined as a decreased estimated glomerular filtration rate (eGFR) with diagnosis by physicians, and CKD of undetermined etiology (CKDu), defined as CKD excluding common traditional etiologies. We calculated the county-wide average ambient temperature from a climate reanalysis dataset (ERA5-Land). All CKD cases were matched 1:2 to non-CKD participants by age and biological sex. We estimated the odds ratios (ORs) of CKD and CKDu for farmers and changes in mean ambient temperature (°C) before the examination.

Results

We identified 844,412 farmers and 3,750,273 nonfarmers. Among 24.9% of farmers and 7.4% of nonfarmers with reduced kidney function, only 1 in 7 received a diagnosis of CKD. The farming occupation was independently predictive of CKDu (OR = 1.09, 95% confidence interval [CI] = 1.001-1.18) but not CKD. Increased ambient temperature (°C) was associated with a higher risk of CKD (OR = 1.023, 95% CI = 1.017-1.029), with particularly strong associations observed among middle-aged participants and diabetics.

Conclusions

Taiwanese farmers might have a higher risk of developing CKDu. Outdoor heat exposure is associated with the development of CKD, and middle-aged participants and those with diabetes are more vulnerable than the general population.

Physical Inactivity Prevalence in the Islamic World: An Updated Analysis of 47 Countries

BACKGROUND

Physical inactivity prevalence estimates for youth and adults have been published on a global scale and for various geographical and geopolitical permutations. Only one such study has presented estimates for adults in Muslim countries, and it is nearly 10 years old. I conducted an update of this study by incorporating newer data, refining methods, and including youth estimates.

METHODS

I identified 47 Muslim countries with physical inactivity data for youth, adults, or both. Data were extracted by country primarily from global estimates reported by Guthold et al in 2018 and 2020 and from World Health Organization surveillance data repositories. Weighted prevalence calculations for total prevalence and by sex, ethnicity (Arab vs non-Arab), and country income group accounted for country population, study sample size, and a country's proportion of Muslims. Z tests and chi-square tests, and follow-up odds ratios and percentage deviations, respectively, were used to determine differences by sex, ethnicity, and country income group.

RESULTS

Overall physical inactivity prevalence was 84.2% (youth) and 29.6% (adults). Gaps favoring males over females were observed for youth (5.6% lower prevalence) and adults (9.6% lower prevalence). Gaps favoring non-Arabs over Arabs were observed for youth (3.9% lower) and adults (3.8% lower). No pattern emerged for country income group for youth; however, prevalence for adults trended upward across income groups from low (22.7%) to high (62.0%).

CONCLUSIONS

Gaps by sex and ethnicity have narrowed since the original report and prevalence values are somewhat higher than current global estimates.

Lifestyle parameters of Japanese agricultural and non-agricultural workers aged 60 years or older and less than 60 years: A cross-sectional observational study

OBJECTIVES

Improving the lifestyle of occupational workers is essential for extending healthy life expectancy. We investigated various lifestyle-related items in a rural Japanese population and compared them between agricultural and non-agricultural workers.

METHODS

This cross-sectional study was conducted as a part of the "Iwaki Health Promotion Project." Lifestyle-related items such as sleep, work hours, nutrition, health-related quality of life, and proportion of time spent performing each daily activity were compared between agricultural and non-agricultural workers in the ≥60 years (n = 251) and <60 years (n = 560) age groups.

RESULTS

Agricultural workers had significantly lower Pittsburgh Sleep Quality Index total scores than non-agricultural workers in the <60 years group. The proportion of participants with more than 5 weekly working days was high among agricultural workers in both groups. Additionally, the proportion of people who worked more than 8 h per day was high among agricultural workers in both age groups. Energy intake per day was high among agricultural workers in the <60 years group. In both age groups, agricultural workers slept and woke up approximately 40 min earlier than did non-agricultural workers.

CONCLUSIONS

Agricultural workers have better sleep habits but work longer than non-agricultural workers, with some differences in energy intake and proportion of time spent on each daily activity. These differences should be considered when planning lifestyle intervention programs for agricultural workers.

Serum klotho concentrations in older men with hypertension or type 2 diabetes during prolonged exercise in temperate and hot conditions

PURPOSE

Klotho is a cytoprotective protein that increases during acute physiological stressors (e.g., exercise heat stress), although age-related declines in klotho may underlie cellular vulnerability to heat stress. The present study aimed to compare serum klotho in healthy older men and men with type 2 diabetes (T2D) or hypertension (HTN) during prolonged exercise in temperate or hot conditions.

METHODS

We evaluated serum klotho in 12 healthy older men (mean [SD]; 59 years [4]), 10 men with HTN (60 years [4]), and 9 men with T2D (60 years [5]) before and after 180 min of moderate-intensity (fixed metabolic rate of 200 W/m²; ~ 3.4 METs) exercise and 60 min of recovery in temperate (wet-bulb globe temperature (WBGT) 16 °C) and hot (WBGT 32 °C) environments. Core temperature (rectal), heart rate (HR), and heart rate reserve (HRR) were measured continuously while klotho was measured at the end of baseline, exercise, and recovery.

RESULTS

Total exercise duration was reduced during the hot condition in older men with HTN and T2D than healthy older men (both p ≤ 0.049), despite similar core temperatures, HR, and HRR. Klotho was higher than rest following exercise in the heat in healthy older men (+ 191 pg/mL [189]; p < 0.001) and responses were greater (p = 0.036) than men with HTN (+ 118 pg/mL [49]; p = 0.030), although klotho did not increase in men with T2D (+ 4 pg/mL [71]; p ≥ 0.638).

CONCLUSION

Given klotho's role in cytoprotection, older men with HTN and especially T2D may be at increased cellular vulnerability to prolonged exercise or physically demanding exercise in the heat.

Population Characteristics, Symptoms, and Risk Factors of Idiopathic Chilblains: A Systematic Review, Meta-Analysis, and Meta-Regression

BACKGROUND

Chilblains/perniosis is a non-freezing cold injury causing painful inflammatory skin lesions. Its pathogenesis remains poorly understood because it is often studied as secondary to other underlying conditions.

METHODS

We systematically investigated the population characteristics, symptoms, and predisposing factors of chilblains in healthy adults exposed to cool/cold environments. We screened PubMed, Embase, and Cochrane Library, and we adopted PRISMA reporting guidelines (PROSPERO: CRD42021245307). The risk of bias was assessed by two independent reviewers (RTI item bank). Random-effects model meta-analyses were performed to calculate the pooled prevalence of histopathological features. Mixed-effects meta-regressions were used to assess other sources of between-study heterogeneity.

RESULTS

Thirteen studies (477 patients) were included. Chilblains affect more women than men, up to 12% of the body skin surface, and most frequently, the hands and fingers. Meta-analyses of nine studies (303 patients) showed a frequent presence of perivascular lymphocytic infiltrate (81%), basal epidermal-cell layer vacuolation (67%), papillary dermal edema (66%), and perieccrine lymphocytic infiltrate (57%). Meta-regressions (p ≤ 0.05) showed that smoking and frequent occupational exposure to water increase the likelihood of histopathological features.

CONCLUSIONS

The population characteristics, symptoms, and predisposing factors of chilblains revealed in this analysis should be incorporated in medical care to improve the condition's diagnosis and management.

Food Services in the Tourism Industry in Terms of Customer Service Management: The Case of Poland

The catering market in Poland, especially in such areas as the Old Town in Gdańsk, is constantly developing, and in recent years there has been a great development in gastronomic offerings; therefore, the potential in this sector is significant. The gastronomic services market in Gdańsk is subject to segmentation due to the diversity of consumer needs and the location of the outlets. New points are constantly appearing on the gastronomic map of this historical part of Tri-City, where every tourist, regardless of the adopted form of tourism, can satisfy his or her needs without any problems. The authors aimed to analyse the impact of catering services on the tourism industry. In particular, the study is an attempt to identify the functioning of the contemporary culinary market and the conditions for the development of catering services and to describe the forms of enterprises providing this service. The variety of aspects of the research subject matter, oscillating around the main objective, made it necessary to formulate the following research hypotheses: first hypothesis (H1)—catering services influence the management of the tourism industry; second hypothesis (H2)—the tourist is the main determinant shaping demand; third hypothesis (H3)—the tourist contributes to benefits in the sphere of supply. The research tool was two structured, short survey questionnaires used to verify the hypothesis. The survey was conducted during the summer of 2018. The survey involved 20 restaurateurs from the Old Town in Gdańsk and 438 random tourists over 15 years old. The survey of tourists can be characterised as randomised focus groups. The questionnaire addressed to owners of catering establishments was a representative survey. The implication of research carried out among representatives of the tourism segment is the development of a foodservice market based on a marketing strategy that takes into account the specific needs of consumers and the constant monitoring of market behaviour in order to keep up with the changes that occur in it.

Occupational heat strain in outdoor workers: A comprehensive review and meta-analysis

The present comprehensive review (i) summarizes the current knowledge on the impacts of occupational heat stress on outdoor workers, (ii) provides a historical background on this issue, (iii) presents a meta-analysis of published data, (iv) explores inter-individual and intra-individual factors, (v) discusses the available heat mitigation strategies, (vi) estimates physical work capacity, labour productivity, and metabolic rate for the year 2030, and (vii) provides an overview of existing policy and legal frameworks on occupational heat exposure. Meta-analytic findings from 38 field studies that involved monitoring 2,409 outdoor workers across 41 jobs in 21 countries suggest that occupational heat stress increases the core (r = 0.44) and skin (r = 0.44) temperatures, as well as the heart rate (r = 0.38) and urine specific gravity (r = 0.13) of outdoor workers (all p < 0.05). Moreover, it diminishes the capacity of outdoor workers for manual labour (r = -0.82; p < 0.001) and is responsible for more than two thirds of the reduction in their metabolic rate. Importantly, our analysis shows that physical work capacity is projected to be highly affected by the ongoing anthropogenic global warming. Nevertheless, the metabolic rate and, therefore, labour productivity are projected to remain at levels higher than the workers' physical work capacity, indicating that people will continue to work more intensely than they should to meet their financial obligations for food and shelter. In this respect, complementary measures targeting self-pacing, hydration, work-rest regimes, ventilated garments, and mechanization can be adopted to protect outdoor workers.

Indicators to assess physiological heat strain - Part 2: Delphi exercise

In a series of three companion papers published in this Journal, we identify and validate the available thermal stress indicators (TSIs). In this second paper of the series, we identified the criteria to consider when adopting a TSI to protect individuals who work in the heat, and we weighed their relative importance using a Delphi exercise with 20 experts. Two Delphi iterations were adequate to reach consensus within the expert panel (Cronbach's α = 0.86) for a set of 17 criteria with varying weights that should be considered when adopting a TSI to protect individuals who work in the heat. These criteria considered physiological parameters such as core/skin/mean body temperature, heart rate, and hydration status, as well as practicality, cost effectiveness, and health guidance issues. The 17 criteria were distributed across three occupational health-and-safety pillars: (i) contribution to improving occupational health (55% of total importance), (ii) mitigation of worker physiological strain (35.5% of total importance), and (iii) cost-effectiveness (9.5% of total importance). Three criteria [(i) relationship of a TSI with core temperature, (ii) having categories indicating the level of heat stress experienced by workers, and (iii) using its heat stress categories to provide recommendations for occupational safety and health] were considered significantly more important when selecting a TSI for protecting individuals who work in the heat, accumulating 37.2 percentage points. These 17 criteria allow the validation and comparison of TSIs that presently exist as well as those that may be developed in the coming years.

Work strain and thermophysiological responses in Norwegian fish farming - a field study

Fish farming is considered as a physical demanding occupation, including work operations with high workloads and awkward work positions for prolonged periods of time. Combined with potential challenging environmental conditions, these factors may negatively affect work performance, comfort and health. This study aimed to explore work strain and thermophysiological responses in Norwegian fish farming. Fourteen workers (age 35 ± 15 yrs) from four fish farms participated in the field studies, and measurements of heart rate (HR), core- and skin temperatures were registered continuously during a work shift. Questions about subjective thermal sensation and comfort were answered. This study has shown that workers at fish farms are periodically exposed to high or low levels of work strain, where the high workloads are manifested as increased core temperature and HR when working. The results are expected to give a better understanding of work strain and environmental challenges during fish farm operations.

Hot weather and heat extremes: health risks

Hot ambient conditions and associated heat stress can increase mortality and morbidity, as well as increase adverse pregnancy outcomes and negatively affect mental health. High heat stress can also reduce physical work capacity and motor-cognitive performances, with consequences for productivity, and increase the risk of occupational health problems. Almost half of the global population and more than 1 billion workers are exposed to high heat episodes and about a third of all exposed workers have negative health effects. However, excess deaths and many heat-related health risks are preventable, with appropriate heat action plans involving behavioural strategies and biophysical solutions. Extreme heat events are becoming permanent features of summer seasons worldwide, causing many excess deaths. Heat-related morbidity and mortality are projected to increase further as climate change progresses, with greater risk associated with higher degrees of global warming. Particularly in tropical regions, increased warming might mean that physiological limits related to heat tolerance (survival) will be reached regularly and more often in coming decades. Climate change is interacting with other trends, such as population growth and ageing, urbanisation, and socioeconomic development, that can either exacerbate or ameliorate heat-related hazards. Urban temperatures are further enhanced by anthropogenic heat from vehicular transport and heat waste from buildings. Although there is some evidence of adaptation to increasing temperatures in high-income countries, projections of a hotter future suggest that without investment in research and risk management actions, heat-related morbidity and mortality are likely to increase.

Excessing Energy Expenditure in Female Healthcare Workers in a University Hospital

INTRODUCTION

The assessment of energy expenditure (EE) at workplaces maintains a central topic in occupational health due to increasing work-related issues. Today 80% of employees in the healthcare system are women. Limited research concerning their physical activity at work is available. The purpose of the study was the investigation of body composition, maximum physical capacity and quantification of physical work activity for female healthcare workers under real-time conditions.

METHODS

Occupational physical activity (PA) of 33 female healthcare workers in a university hospital was quantified. Health associate professionals (HAP), health professionals (HP), and females working from cleaners and helpers (CH) department participated. All underwent cardio pulmonary exercise test. For every working task VO2, VCO2 and RER were measured and EE was calculated individually for each task.

RESULTS

Forty-two different working tasks were identified and grouped in seven categories to compare physical activity (PA): 'office and laboratory work', 'bedside patient care', 'instrument reprocessing, packing boxes', 'walking with patient, or alone', 'pushing carts or wheelchairs', 'strenuous cleaning in bent posture' and 'lifting heavy boxes, weights or items'. By comparing groups of healthcare workers, CH and HAP spent significant (p < 0.01) more EE (in kcal/min) 3.9 resp. 3.2 than HP 2.5. Light PA e.g. office and laboratory work (2.7 ± 0.6) and bedside patient care (2.9 ± 0.7) were accomplished by HP and HAP while HAP and CH performed moderate PA such as 'packing boxes' (3.6 ± 0.8), 'pushing carts' and 'strenuous cleaning' (4.7 ± 0.9). Work performed by CH and HAP, i.e. 'strenuous cleaning' and 'lifting heavy items' showed highest kcal per kg Fat Free Mass (FFM) per hour with 5.80 [4.05-7.81] and 6.94 [5.18-9.03] kcal/kgFFM/h.

CONCLUSION

Our findings lend preliminary support to the hypothesis that the majority of activities in female healthcare workers were of low and moderate PA and can be accomplished by middle aged and even older female workers. CH performed tasks with heavy physical activities (PA) like cleaning and lifting heavy weights. HAP performed light/moderate PA below their maximum physical capacity.

The Impacts of Sun Exposure on Worker Physiology and Cognition: Multi-Country Evidence and Interventions

BACKGROUND

A set of four case-control (n = 109), randomized-controlled (n = 7), cross-sectional (n = 78), and intervention (n = 47) studies was conducted across three countries to investigate the effects of sun exposure on worker physiology and cognition.

METHODS

Physiological, subjective, and cognitive performance data were collected from people working in ambient conditions characterized by the same thermal stress but different solar radiation levels.

RESULTS

People working under the sun were more likely to experience dizziness, weakness, and other symptoms of heat strain. These clinical impacts of sun exposure were not accompanied by changes in core body temperature but, instead, were linked with changes in skin temperature. Other physiological responses (heart rate, skin blood flow, and sweat rate) were also increased during sun exposure, while attention and vigilance were reduced by 45% and 67%, respectively, compared to exposure to a similar thermal stress without sunlight. Light-colored clothes reduced workers' skin temperature by 12-13% compared to darker-colored clothes.

CONCLUSIONS

Working under the sun worsens the physiological heat strain experienced and compromises cognitive function, even when the level of heat stress is thought to be the same as being in the shade. Wearing light-colored clothes can limit the physiological heat strain experienced by the body.

Occupational Heat Stress: Multi-Country Observations and Interventions

BACKGROUND

Occupational heat exposure can provoke health problems that increase the risk of certain diseases and affect workers' ability to maintain healthy and productive lives. This study investigates the effects of occupational heat stress on workers' physiological strain and labor productivity, as well as examining multiple interventions to mitigate the problem.

METHODS

We monitored 518 full work-shifts obtained from 238 experienced and acclimatized individuals who work in key industrial sectors located in Cyprus, Greece, Qatar, and Spain. Continuous core body temperature, mean skin temperature, heart rate, and labor productivity were collected from the beginning to the end of all work-shifts.

RESULTS

In workplaces where self-pacing is not feasible or very limited, we found that occupational heat stress is associated with the heat strain experienced by workers. Strategies focusing on hydration, work-rest cycles, and ventilated clothing were able to mitigate the physiological heat strain experienced by workers. Increasing mechanization enhanced labor productivity without increasing workers' physiological strain.

CONCLUSIONS

Empowering laborers to self-pace is the basis of heat mitigation, while tailored strategies focusing on hydration, work-rest cycles, ventilated garments, and mechanization can further reduce the physiological heat strain experienced by workers under certain conditions.

Sustainable solutions to mitigate occupational heat strain - an umbrella review of physiological effects and global health perspectives

BACKGROUND

Climate change is set to exacerbate occupational heat strain, the combined effect of environmental and internal heat stress on the body, threatening human health and wellbeing. Therefore, identifying effective, affordable, feasible and sustainable solutions to mitigate the negative effects on worker health and productivity, is an increasingly urgent need.

OBJECTIVES

To systematically identify and evaluate methods that mitigate occupational heat strain in order to provide scientific-based guidance for practitioners.

METHODS

An umbrella review was conducted in biomedical databases employing the following eligibility criteria: 1) ambient temperatures > 28 °C or hypohydrated participants, 2) healthy adults, 3) reported psychophysiological (thermal comfort, heart rate or core temperature) and/or performance (physical or cognitive) outcomes, 4) written in English, and 5) published before November 6, 2019. A second search for original research articles was performed to identify interventions of relevance but lacking systematic reviews. All identified interventions were independently evaluated by all co-authors on four point scales for effectiveness, cost, feasibility and environmental impact.

RESULTS

Following screening, 36 systematic reviews fulfilled the inclusion criteria. The most effective solutions at mitigating occupational heat strain were wearing specialized cooling garments, (physiological) heat acclimation, improving aerobic fitness, cold water immersion, and applying ventilation. Although air-conditioning and cooling garments in ideal settings provide best scores for effectiveness, the limited applicability in certain industrial settings, high economic cost and high environmental impact are drawbacks for these solutions. However, (physiological) acclimatization, planned breaks, shading and optimized clothing properties are attractive alternative solutions when economic and ecological sustainability aspects are included in the overall evaluation.

DISCUSSION

Choosing the most effective solution or combinations of methods to mitigate occupational heat strain will be scenario-specific. However, this paper provides a framework for integrating effectiveness, cost, feasibility (indoors and outdoor) and ecologic sustainability to provide occupational health and safety professionals with evidence-based guidelines.

Physical activity and work activities in Florida agricultural workers

BACKGROUND

Laboring in hot and humid conditions is a risk factor for heat-related illnesses. Little is known about the amount of physical activity performed in the field setting by agricultural workers, a population that is among those at highest risk for heat-related mortality in the United States.

METHODS

We measured accelerometer-based physical activity and work activities performed in 244 Florida agricultural workers, 18 to 54 years of age, employed in the fernery, nursery, and crop operations during the summer work seasons of 2015-2017. Environmental temperature data during the participant's workdays were collected from the Florida Automated Weather Network and used to calculate wet bulb globe temperature (WBGT). Generalized linear mixed model regression was used to examine the association between WBGT on physical activity, stratified by the agricultural sector.

RESULTS

Fernery workers had the highest overall volume of physical activity, spending nearly 4 hours in moderate to vigorous activity per workday. Activity over the course of the workday also differed by the agricultural sector. A reduction on average physical activity with increasing environmental temperature was observed only among crop workers.

CONCLUSIONS

The quantity and patterns of physical activity varied by the agricultural sector, sex, and age, indicating that interventions that aim to reduce heat-related morbidity and mortality should be tailored to specific subpopulations. Some workers did not reduce overall physical activity under dangerously hot environmental conditions, which has implications for policies protecting worker health. Future research is needed to determine how physical activity and climatic conditions impact the development of heat-related disorders in this population.

A free software to predict heat strain according to the ISO 7933:2018

Our primary objective in this study was to design and implement the FAME Lab PHS Calculator software (PHS_FL) (www.famelab.gr/research/downloads), a free tool to calculate the predicted heat strain of an individual based on ISO 7933:2018. Our secondary objective was to optimize the practicality of the PHS_FL by incorporating knowledge from other ISO standards and published literature. The third objective of this study was to assess: (i) the criterion-related validity of the PHS_FL by comparing its results against those obtained using the original ISO 7933:2018 code; and (ii) the construct validity of the PHS_FL by comparing its results against those obtained via field experiments performed in human participants during work in the heat. Our analysis for criterion validity demonstrates that PHS_FL provides valid results within the required computational accuracy, according to Annex F of ISO 7933:2018. The construct validity showed that root mean square errors (RMSE) and 95% limits of agreement (LOA) were minimal between measured and predicted core temperature (RMSE: 0.3°C; LOA: 0.06 ± 0.58°C) and small between measured and predicted mean skin temperature (RMSE: 1.1°C; LOA: 0.59 ± 1.83°C). In conclusion, the PHS_FL software demonstrated strong criterion-related and construct-related validity.

Accuracy of metabolic rate estimates from heart rate under heat stress-an empirical validation study concerning ISO 8996

The standard ISO 8996 provides methods for the determination of metabolic rate from measured oxygen consumption (M_VO2), as well as simplified estimation algorithms based on heart rate (M_HR). We quantified the accuracy of these methods by comparing M_HR with M_VO2 measured in 373 climatic chamber experiments under different workloads and widely varying heat stress conditions. While our results confirmed the 5% accuracy level for M_VO2, M_HR considerably overestimatedM_VO2 due to the rise in core temperature concomitantly increasing heart rate by approximately 30 bpm/°C resulting in an overall error of 43%. After individually correcting for this bias the accuracy was 10-15% as stipulated by the standard. Thus, methods correcting for the thermal component of heart rate, e.g. by introducing intermittent resting periods of sufficient length of at least five min when investigating heat stress at workplaces, should become a mandatory element in the ongoing revision of the relevant standards.