Modern Occupational Diseases: Diagnosis, Epidemiology, Management and Prevention

By Bentham Science Publishers

Occupational disease is an important public health problem of the 21st century. Occupational disease still accounts for many preventable illnesses and injuries in the workplace. It is important to incorporate modern knowledge of disease epidemiology and cutting-edge diagnostic methods and treatment with the most recent developments in the management and prevention methods to better control work-related diseases and injuries. This book covers a selection of the common occupational diseases and injuries. It offers accurate, current information on the history, causes, diagnosis, management and prevention of several occupational diseases.

Key features:
- 14 chapters contributed by more than 30 experts in occupational and preventive medicine
- Comprehensive treatment of the history, causes, diagnosis, management and prevention of many important occupational diseases (including asbestosis, silicosis, work-related asthma, occupational cancer, mesothelioma, arsenic, and other diseases.).
- Each chapter highlights the latest research findings and cutting-edge technologies
- References for further reading

Modern Occupational Diseases: Diagnosis, Epidemiology, Management and Prevention serves as a useful guide for all readers interested in occupational diseases. The suggested readership includes trainees in occupational medicine, general practitioners, medical students, graduate students in public health programs, occupational health nurses, and professionals involved in occupational health and safety roles at public and private levels.

• Language: English
• Publisher: Bentham Science Publishers
• Release date: Dec 31, 2002
• ISBN: 9789815049138

Book preview

Occupational Disease in the 21st Century: COVID-19, Climate Change, and the Fourth Industrial Revolution

Kelly M. Hager¹, Brian Linde¹, Carrie A. Redlich¹, *

¹ Yale Occupational and Environmental Medicine Program, Department of Medicine, Yale University School of Medicine, New Haven, CT, USA

Abstract

The beginning of the 21st century is experiencing tremendous social, political, and technological changes, combined with unprecedented climate change. Recent trends towards non-standard employment, growing economic and health disparities, and the decline of unions have served to undercut worker health and safety protections. Traditional workplace hazards remain important and preventable contributors to injuries and illness while new and/or newly recognized work factors are also becoming apparent. To meet the needs of the changing times, the traditional focus of occupational safety and health on industrial hazards is shifting toward a more holistic framework that incorporates other work stressors, underlying disparities, and the interactions with non-work factors. In this chapter, the major issues affecting workers today are examined through the two defining public health crises of our time, the COVID-19 pandemic and climate change. Initial lessons and observations from these global challenges inform the direction occupational safety and health will take to protect workers and prepare for an uncertain future.

Keywords: COVID-19, Climate change, Heat stress, Health disparities, Health, Occupational disease, Occupational safety, Work organization.

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* Corresponding author Carrie A. Redlich: Yale Occupational and Environmental Medicine Program, Department of Medicine, Yale University School of Medicine, New Haven, CT, USA; Tel: [phone]; E-mail: [e-mail]

INTRODUCTION

Though frequently overlooked, work is a key social determinant of health, impacting health beyond traditionally recognized occupational illnesses and injuries. Factors such as job security, work environment and exposures, as well as job demands all contribute to an individual’s overall health. These work factors change as technology and the economy change. As work factors evolve, so do the ways work impacts health.

The beginning of the 21st century is a time of unprecedented social and technological change. Economic trends of the past fifty years towards more flexible and temporary employment and more fragmented industries and organizations have served to undercut several worker protections, just as the future of work itself is on the verge of major transformations. To meet the needs of workers during this period of growth, the traditional focus of occupational safety and health on industrial exposures is shifting toward a more holistic framework that incorporates non-industrial indoor air exposures, psychosocial stressors, underlying disparities, and interactions with non-work factors.

In this chapter, the major issues affecting workers today are examined through the two defining public health crises of our time: the COVID-19 pandemic and climate change. First, we review the impact of non-standard work and modern work organization on worker health, as well as how work contributes to health disparities overall. The COVID-19 pandemic is then presented with a focus on its effects on worker health, including the disparity in health outcomes between essential and non-essential workers. Next, we examine how climate change is impacting occupational safety and health, both in terms of worker health (e.g. the effects of heat stress and air pollution on vulnerable workers) as well as in hastening larger changes within the field in terms of future planning and preparedness.

Finally, we discuss how lessons learned from current occupational health challenges highlight priority areas for the field going forward. Rapid changes in science, technology, economic patterns, and the environment itself creates uncertainty and volatility, and carry the potential to threaten worker safety. Occupational medical surveillance and research, policy and regulation, training and education all require investment and updating to meet the challenges facing worker protection in the 21st century. Selected priority areas are briefly reviewed.

THE CHANGING ECONOMY/CHANGING STRUCTURE OF WORK

Bernardino Ramazzini (1633-1714), considered the founder of occupational medicine, observed that work and health are inextricably linked [1]. As society and technology evolve, the types and conditions of work change, with resultant impacts on health and disease. In 2016, world leaders met at the World Economic Forum in Davos, Switzerland, to discuss the emerging era of rapid change in work, science, and technology known as the Fourth Industrial Revolution [2].

Briefly, the three Industrial Revolutions that preceded the current period were defined by the advent of steam power and mechanization in the mid-1700s, the introduction of electric power and mass production in the latter half of the 1800s, and the incorporation of electronic devices and computers to automate production at the end of the 1900s. Each of these revolutions fundamentally changed society and the world of work, and introduced new occupational health and safety challenges, as well as the resurgence of well-known hazards that previously had been better controlled. Table 1 summarizes major occupational health challenges of the 21st century.

Table 1 Major 21st century inter-related occupational health challenges.

The Fourth Industrial Revolution is unique due to the speed and breadth of changes and the development of new emerging technologies such as artificial intelligence, robotics, the internet of things, autonomous vehicles, 3D printing, nanotechnology, biotechnology, materials science, energy storage, and quantum computing [3]. The number and scope of these disruptive advancements make it difficult to predict how the Fourth Industrial Revolution will unfold and what the precise impact will be on work and society.

The anticipated changes in occupational medicine that will accompany the Fourth Revolution will likely impact work structures that expanded following WWII. The initial decades following WWII were ones of general economic stability and prosperity through the Western world, and it was in this context that the standard employment relationship developed [4]. Defined as permanent, full-time, year-round employment with comprehensive job-related benefits as well as strong employment-related rights and protections, including the right to collective representation, this standard employment relationship continued into the mid-1970s. Starting in the 1970s, multiple factors, including the economic oil shocks, worldwide recession, political shifts towards less government regulation and less union representation, began the trends towards reduced employment protections, the increased use of outsourcing and temporary workers and greater income disparities.

The working environment has continued to move away from the traditional post-WWII employment structure in recent years, attenuated by the Great Recession of 2008 and most recently COVID-19. Multiple economic, political and social factors have contributed to the continued rise in income inequality and health disparities, including work factors. Together, precarious employment, non-standard work arrangements, the decline of labor unions, and occupational health disparities are shaping occupational health in the 21st century [4].

Non-standard Work and Precarious Employment

Known by a variety of names, including temporary work, contingent, or contract work, to name a few, non-standard work is becoming more prominent in today’s society [5]. In 2013, researchers at the National Institute for Occupational Safety and Health (NIOSH) reported that roughly 18% of adults work in non-standard arrangements [6]. Due to the lack of standardized definitions of non-standard work as well as the heterogeneous nature of this workforce, it is difficult to obtain an accurate count, however, estimates in the literature range between 8% to 18% of the total workforce [5] and increasing. Non-standard workers are now found in both low-wage and higher-wage occupations.

While there are no standardized definitions of work arrangements, non-standard work shares a common feature of there being no expectation of permanent hire. Such precarious work arrangements do not share the same access to legal protections and social benefits as standard arrangement work, leaving workers especially vulnerable. A growing body of evidence indicates that workers in non-standard arrangements are at higher risk of work-related injury and illness [7]. A systematic review of international, peer-reviewed studies found that 7 of 13 separate reports showed an increased risk of occupational injuries among temporary workers [8]. Authors from this group also looked at the relationship between temporary employment and mortality using longitudinal data from 10 towns in Finland over 11 years and identified that the overall mortality rate of temporary workers was 1.2-1.6 times greater compared to permanent employees [9]. Notably, these researchers also found that moving from temporary to permanent employment was associated with a lower risk of death compared to those who remained continuously in temporary employment.

There are a number of potential explanations for why such differential health risks associated with non-standard work may exist. Non-standard workers may have shorter job tenures and resultant lack of experience and may not be integrated into the workplace as effectively in terms of job skills training, worker safety training, and access to personal protective equipment, resulting in greater exposures to workplace hazards. Lacking a social connection to the workplace, these workers may also be isolated, not ask for assistance from other workers, and be less likely to object to hazardous work.

Finally, as noted earlier, non-standard workers lack some of the legal protections that standard workers are afforded [5].

Thus non-standard workers are vulnerable to unfair treatment and lack the ability to negotiate pay and benefits. In addition to an increased risk of work-related injury and illness, precarity and job insecurity are associated with adverse effects on mental health [4]. Survivors of downsizing generally take on a greater workload and experience increased job strain and sustained job insecurity [10]. Deleterious effects of precarious employment have been shown to extend beyond the individual to adversely impact families and communities [4].

Work Organization

As the nature of work has evolved in the past years with changes in technologies, shifting from an economy based on manufacturing jobs to one dominated by the service sectors in the U.S., the proportion of jobs with a fixed schedule and location has decreased [11]. Innovations in information communication technologies such as internet-connected laptops and smartphones make it possible to work from nearly anywhere, at any time. Prior to 2020, approximately 20% of U.S. workers were engaged in remote or mobile work, which greatly increased with COVID-19, and will likely continue post-pandemic as remote work and telework become more accepted modes of work [12]. While the flexibility of this type of work can have benefits, it has also blurred the lines between work and non-work, with some workers engaging in longer working hours and experiencing difficulties disengaging from work. Stress associated with conflicts between work and personal responsibilities is increasingly impacting occupational health and illness in the 21st century [13].

To quantify the potential effects of work stress burdens, the WHO/ILO Joint Estimates of the Work-related Burden of Disease and Injury recently performed the first global analysis of the loss of life and health associated with long working hours [13a]. Based on data from 194 countries between 2000-2016, they estimated that 488 million people were exposed to long working hours (defined as greater than 55 hours per week) with an exposure-associated 745,194 attributable deaths due to heart disease and stroke. This represented 4.9% of all deaths and accounted for about one-third of the total estimated work-related burden of disease globally, While warranting greater attention to the hazards of long work hours.

While remote work can create new work opportunities, it can also increase work-family conflict and work-related stress [13b]. The pressure to respond to work e-mail and text messaging, known as workplace telepressure, plays an important role in work-family conflict and work-related stress. Though information communication technologies offer employees greater autonomy for timing and location of work, the pressure to work at all hours is associated with a negative effect on the balance of work and home responsibilities. In addition to the effect on work-life balance, the defining feature of workplace telepressure is its impact on stress-related outcomes: increased burnout, elevated stress levels, and poor sleep practices [14].

Nearly two-thirds of adults identify work as a significant source of stress, making work-related stress one of the most important health and safety issues in the modern world of work.

As future demands of work increase and human connections of the physical workplace decrease, it is expected that workers will experience escalating frequent and intense emotional and mental stress [12]. Stress is linked to a myriad of negative health outcomes, and stressful situations spur the body into the protective fight or flight mode. When stress is short-lived, these physiological changes pose little risk. Sustained exposure to stress without the opportunity to recover leads to an increased risk of burnout as well as anxiety and depression. Due to the potentially devastating personal and professional consequences of stress-related disease, stress prevention efforts and stress management are priority areas for occupational health and safety in the 21st century.

CONTRIBUTION OF WORK TO OTHER HEALTH DISPARITIES

It is well established that adults with better jobs enjoy better health than those with less prestigious, lower-wage jobs [15]. The Whitehall Studies, which began with an examination of mortality rates of British civil servants against their civil service grade levels over a ten-year period from 1967-1977, established work as a social determinant of health [5]. Whitehall I, as well as subsequent Whitehall studies, demonstrated a strong, inverse association between civil service grade levels and mortality rates. While several factors are identified as contributing to this association, a key underpinning is that psychosocial stressors, as well as exposure to physical and chemical hazards, are disproportionately distributed to workers of lower socioeconomic status. Technological displacement associated with the future of work threatens to further accentuate occupational health disparities by replacing certain lower-wage jobs and consolidating the power of higher-status jobs.

The likelihood of holding a high-status job and avoiding a host of negative exposures at work are differentially distributed across social groups [16]. Educational attainment, racial/ethnic group membership, immigrant status, and gender all influence an individual’s access to healthy work [17]. In 2014, NIOSH used Bureau of Labor Statistics data to examine the relationship between high-risk occupations and demographic variables [18]. They found that employment in high-injury/illness occupations was independently associated with being male, Black race, foreign-birth, not having a high school degree, and low wages.

Equitable distribution of the benefits and risks associated with new work arrangements and organization is one of the central challenges to the future of work. Workplace discrimination, inadequate training, communication challenges due to literacy or language barriers, and pressure to accept risky work assignments due to economic insecurity are all ways in which occupational health disparities are heightened along social and cultural lines [19]. As today’s workforce continues to diversify, the gender, age, race, nativity, and economic disparities among working groups grow [20].

Policies and regulations, as well as labor unions, all play important roles in protecting workers. Established in 1970, the Occupational Safety and Health Administration (OSHA) was created to assure safe and healthful working conditions for working men and women, through the promulgation and enforcement of OSHA standards [16]. Unfortunately, OSHA has been understaffed, underfunded, and lacking authority to impose strong penalties for violations of safety and health regulations [21]. The maximum total penalty for a deadly OSHA violation is roughly $10,000 and it is estimated that given the number of current OSHA inspectors, it would take the agency 165 years to visit every workplace once [21a]. These challenges to OSHA regulations and enforcement threaten the health of U.S. workers.

Labor unions have historically been involved in creating healthy and safe workplaces and advocating for important workplace safety regulations [22]. As President Barack Obama stated: The 40-hour work week, the minimum wage, family leave, health insurance, Social Security, Medicare, retirement plans, the cornerstones of the middle-class security all bear the union label. [23]. When American labor unions were at their most powerful in the mid-1950s, more than one third of U.S. workers belonged to unions. In 2014, American labor union density was at a 99-year low, and currently, only approximately one in ten U.S. workers is in a union [23].

Low union participation has left workers vulnerable to reduced health and safety standards and has weakened the role of organized labor as a power equalizer. The decline in union power coincides with the greatest level of economic inequity in the history of the U.S. [22]. In 2012, researchers investigated the relationship between unionization and health in a representative sample of 11,347 full-time workers drawn from The National Opinion Research Center’s General Social Survey [24]. They found evidence of a positive association between union membership and self-rated health, attributed to a number of factors, foremost increased income. Given the fundamental role labor unions played in workplace safety and health protection over the past one hundred years and beyond, the current, low union membership density is an important determining factor shaping the future of occupational disease.

COVID-19 AS AN EXAMPLE OF AN EMERGING OCCUPATIONAL DISEASE AND WORK HEALTH DISPARITIES

Multiple new virulent pathogens have surfaced over the past twenty years, serving as reminders that, despite improved medical science and technology, emerging infections remain an ongoing public health threat in today’s world. Shortly after the first cases of SARS-CoV-2 were reported to the WHO in December 2019, it was declared a public health emergency of international concern [25]. As the situation evolved over the following weeks, the traditional views of the nature of work were challenged, as the pandemic affected workers in unprecedented ways.

Effects on Workers

The COVID-19 pandemic profoundly affected workers across multiple occupations. The early classification of positions as essential and non- essential designated those who were unbound from stay-at-home restrictions to perform job responsibilities determined to be necessary to societal function. Those workers who were deemed essential continued to report to work in-person throughout the pandemic phase of COVID-19, with varying levels of risk mitigation and resources in place to preserve their safety. Outside of the CDC recommendations, there was no unified consensus to shape protocols to protect most workers outside of health care environments. Businesses attempted to mitigate risks by implementing different protective strategies. Development of formal administrative controls, including work policies regarding social distancing and requirements for facemasks/hand hygiene, lagged, resulting in widespread variation in safety practices between occupational environments/organizations, and often, delays in implementation of effective preventive measures [26]. In places where social distancing would be difficult to achieve, engineering controls, including the installation of physical barriers such as clear plexiglass at grocery store checkout stations, were enacted to reduce open-air contact between consumers and workers. Other systemic changes, including reduced open hours in retail establishments, were utilized to reduce exposure risks, also enabling businesses to function with a reduced workforce.

While considered to be the lowest in the hierarchy of controls, personal protective equipment (PPE) was thrust to the forefront in the eyes of the public as the stress placed on global supply chains by the pandemic combined with the sudden rise in demand greatly affected its availability. In healthcare environments, the once abundant and single-use, N95 respirators were rationed and reused for multiple days and even sterilized for redistribution [27, 28]. Commercial cleaners/ janitorial services experienced disinfectant product supply backorders, in addition to personal protective equipment. The shortage of PPE especially impacted healthcare workers, who reported increased work-related stress and burnout secondary to concerns of personal illness or transmission of the disease to their families in the absence of adequate protection [29].

The pandemic also presented challenges for workers considered non-essential. To conform with social distancing regulations and other practices, businesses quickly reorganized and developed strategies to remain productive while keeping their workers safe most notably, a work from home model. This movement of the workforce to the home environment alleviated many viral exposure concerns and provided continuity of pay/work benefits, but was not without hardship. Following the closures of schools and childcare facilities, many working parents were left juggling the responsibilities of in-home childcare/remote education in addition to their daily work responsibilities. Similarly, workers who were essential and still reporting to in-person work who were left without childcare were faced with the difficult decision to continue working or stay at home with their children if alternative arrangements could not be made.

Job insecurity was another aspect impacting worker’s health unmasked by the pandemic. Previous research has shown associations between increased job-security-related stressors and physical/mental health conditions [30, 31 and 31a]. Non-relocatable, non-essential workers who could not work from home suffered great disruption including hour reductions or voluntary/involuntary layoffs. During the early months of the pandemic, unemployment claims surged to record levels, disproportionately affecting retail and food service occupations among others [32].

Health Disparities

COVID-19 brought societal disparities to the forefront. In the early weeks of the pandemic, essential workers within transportation, food service and public service positions continued to work, many initially without guidelines/regulations in place to ensure their safety. An analysis performed of U.S. occupational data prior to the pandemic showed that about 25% of the U.S. workforce were employed in positions that could be performed at home – leaving 108.4 million persons in jobs associated with increased risk of COVID-19. The study also identified significant differences between median annual wages between workers who would likely be able to work from home and those who would not ($30,000 less annual income) – unveiling greater risks among lower-income workers [33].

Data from other countries reveal a greater risk of COVID-19 among lower paid workers. The Office of National Statistics (ONS) figures from England and Wales showed people in low wage, manual labor jobs faced greater risk of dying from COVID-19 compared to higher-paid, white collar workers [34]. COVID-related mortality rates were significantly higher in occupations where physical distancing was difficult, such as men working as security guards, plant machinists, taxi drivers/chauffeurs/chefs, and sales and retail assistants. Previous ONS reports identified that black and ethnic minorities were dying at increased rates compared to whites and were over-represented in high-risk occupations. Similar findings were noted in the United States; A California-based study showed 22% relative excess deaths among working age adults due to COVID-19, with the greatest effects on mortality among essential workers, with excess mortality across all race and ethnic groups, disproportionately affecting Latino and black workers working in food/agriculture and transportation/logistics, respectively [35].

But not all high-exposure essential jobs were associated with increased risks of COVID-19 infection, again, illustrating disparities. The above ONS figures reported increased death rates of homecare workers when compared to the general population (23.4 deaths for every 100,000 men and 9.6 deaths for every 100,000 women), however, health care workers (doctors and nurses) did not have increased fatality rates. Studies within the U.S. and abroad mirror these statistics, showing that physicians generally experienced comparable rates of infection to the general public despite high workplace exposure, likely in part due to the availability of PPE and other protective measures [36]. Such findings are not new phenomena and are consistent with the previously defined concept of the Inverse Hazard Law, described by Krieger et al as the accumulation of health hazards tend to vary inversely with the power and resources of the population affected [37]. Compared to higher-wage workers, low-wage workers have a greater likelihood to be exposed to occupational hazards, with decreased health insurance coverage and less job autonomy [38].

It is well documented that COVID-19 infections occurred with increased frequency in people of color [38a]. Many explanations for these elevated risks have been proposed, including pre-existing health co-morbidities, socioeconomic status and living arrangements [39]. Research suggests this increased vulnerability and the variability in risk for COVID-19 among ethnicities should also include the nature of one’s employment [40]. Using employment data from the Bureau of Labor Statistics Current Population Survey, a study evaluated the frequency of infectious exposures of those in essential industries and their ability to maintain social distance practices. People of color were more likely to be employed in job positions that could not practice social distancing, which supports that variability in COVID-19 risk between races may be partly due to occupational risks [40].

Other Health Effects

The risks of working during the COVID pandemic extended beyond contracting COVID-19; the toll of being separated from family, providing in-home childcare and education, rationing of health care resources, and increased stress impacted mental health. Increased rates of mental health disorders in health care workers during the COVID pandemic have been well documented [41-43]. Similar trends were identified among public health workers. A recent survey conducted among 24,000 tribal, local and territorial health department workers showed 59% worked >41 hours/week during the pandemic, with increased prevalence of mental health conditions correlating to the amount of overtime and participation in COVID-19 response activities [41]. Increased trends in mental health conditions have been seen among other essential workers and the general public.

Protections Looking to the Future

While strides were made in certain aspects of the pandemic response, these above-mentioned situations raise important questions regarding worker safety health inequities and highlight the need to consider work as an important and modifiable social determinant of health. Shutdown policies, while instituted to thwart the spread of infection among the general public, did little to protect essential workers. The need for robust regulations and protections for all workers must be prioritized, with clearly defined and enforceable safety protocols which are consistently and appropriately applied. The pandemic exposed not only the fragility of existing medical surplus supplies and PPE, but also, the inadequacies in policies regarding the distribution and allocation of resources. Recommendations for improved material preparedness include models supporting the development of centralized national supply chain centers, which will oversee procurement, quality control, and distribution of these precious resources during future pandemics [44]. The response must incorporate local and national governments, and strategies for multifocal response plans. Individual employers must develop preparedness plans which support vulnerable employees during pandemics by including protective on the job measures, paid sick leave and other protections in case of adverse outcomes due to exposure. Finally, the experience of the COVID-19 pandemic has increased recognition that infectious diseases can be transmitted in the workplace, including from co-worker to co-worker, a fact of particular importance in the 21st century in the face of emerging infectious diseases and climate change.

CLIMATE CHANGE

Human behavior has significantly influenced the Earth’s natural environment, most notably through the impact of climate change. Earth’s annual average surface temperature has risen dramatically over the 21st century, contributing to increased frequencies of adverse weather, natural disaster events, sea-level rise and air pollution. Workers are particularly susceptible to the adverse effects of climate change, including heat-related illness and respiratory illness secondary to poor air quality. Clinicians should be aware of the direct and indirect effects of climate change on workers, and learn to identify those at greatest risk so early mitigation strategies can be employed to ensure protection and safety.

Climate Change and Human Health

Studies evaluating the impact of climate change have identified wide-spread health effects. Increased temperatures are not only associated with isolated spikes in heat-related morbidity and mortality but are linked to other health outcomes including diabetes, renal disease, and sleep disturbances [45]. Heatwaves are strongly associated with increases in all-cause and cause-specific mortality. Other extreme weather events – including tornadoes, and wildfires – are associated with acute loss of life, and chronic sequelae such as adverse mental health outcomes, malnutrition secondary to food insecurity, and exacerbations of existing illness. Similarly, meteorological factors, including humidity and changes in precipitation and flooding, are associated with respiratory illnesses as increased risks of water-borne infectious diseases [46, 47]. Together, these provide strong evidence that addressing climate change and its effects are integral to ensuring public health safety. The effects of climate change also extend into the workplace due to the daily interplay between personal health, the natural environment and their influence on occupational activities.

Heat Stress

Rising global temperatures and environmental heat are workplace hazards of growing concern [48]. The effects of heat strain have been studied in many countries among various occupations, including miners, agricultural workers, health care workers, and manufacturers [49]. Global temperature rise will disproportionately affect equatorial areas, including tropical areas of high agriculture where many workers are employed outdoors. In addition to heat stress, increased ambient temperatures increase risks of injury, illness, and death in such workers, who are often also working without electrical cooling. Per the International Labor Organization, under currently predicted temperature rises, the elevations would be enough to render 2 percent of all work hours as too hot to work by 2030, which would correspond to significant job loss (an estimated 80 million full-time jobs) [50]. Job loss estimations are upwards of 5% in Asia and Western Africa. While the health burden of climate change likely will be felt the hardest amongst those workers performing manual labor in low-middle income countries, workers in high-income countries will also be impacted.

Recommendations for temperature-related exposure limits are published by the NIOSH, measured as Wet Bulb Globe Temperature (WBGT) – a combination of four environmental factors including temperature, relative humidity, wind speed, and radiation [51]. Studies have shown that working in the heat is associated with decreased worker productivity and increased accidents, work injuries (slips, trips, falls, wounds), and death [52]. These adverse outcomes are found across many indoor and outdoor occupational settings [49, 53].

Performing physical activity in high temperature/humidity can contribute to the development of heat stress due to elevated body temperatures, leading to dire effects including heat exhaustion and death [54]. Multi-layered clothing designed to protect workers from chemical or physical hazards can contribute to increased heat strain through the physical inhibition of natural evaporative cooling processes of the skin. In efforts to stay cool, recommended PPE may be abandoned due to sweaty hands or fogging goggles and extreme discomfort. Warning systems (heat advisories) for the general public usually recommend staying cool indoors during periods of extreme heat. However, such strategies are not realistic for outdoor workers. As temperatures continue to rise, a large amount of outdoor work requiring physical exertion will become prohibitive unless alternative cooling systems are adapted. To maintain safety, employers and workers must be educated to recognize the effects of heat strain, with guidelines on how to safely proceed with activity during times of high temperatures. Adaptations, including an increased number of breaks and access to drinking water every fifteen minutes, should be adopted, in addition to cooling mechanisms [55].

Air Quality

Climate change, air pollution and human health are intertwined. Air pollutants both contribute to the development of climate change and are modified by climate change, and both impact human health. Greenhouse gases (carbon dioxide, nitrous oxide, methane) from human activity are the primary drivers of climate change. Adopted in 2015, the Paris Agreement served as the first unified global climate change agreement to collectively reduce greenhouse gas emissions, providing a framework to impede climate change with the specific goal of limiting global warming [56, 57]. Burning fossil fuels for transportation, heat and electricity is the largest source of greenhouse gas emissions, as well as particulate air pollution. Within the U.S., California has aggressively attempted to combat climate change by adopting robust mitigation policies to improve air quality, specifically the adoption of clean car standards to reduce greenhouse gas emissions to pre-1990 levels by 2030 [58]. Additional states have adopted California’s Zero Emission Vehicle Mandate since it’s induction. In less developed countries, agricultural burning and solid fuel combustion remain the leading generators of carbon emissions; however, as these countries acquire modernizations of more developed nations, diesel fuel and coal-fired power plants are becoming more prominent contributors to air pollution.

Climate change alters multiple components of air quality that can adversely impact human health [59, 60]. For example, rising temperatures increase ozone levels, particulate matter and the risk of wildfires. Outside workers engaged in strenuous physical activity are especially vulnerable to poor air quality. In addition to associations with adverse respiratory and cardiac outcomes, the International Agency for Research on Cancer classifies outdoor air pollution and particulate matter as a Group I human carcinogen [61]. Climate change directly or indirectly increases other harmful pollutants, including polycyclic aromatic hydrocarbons, pesticides, and allergens [61, 62]. Less than ideal working conditions - including long work hours, lack of cooling systems, increased temperatures - can further exacerbate the detrimental effects of these exposures. For example, outdoor farm workers face multiple interacting hazards impacted by climate change, including ozone, pesticides, and heat.

Air quality is also influenced by weather. Arid temperatures and droughts are associated with the development of dust storms; sand/dust containing allergens, fungal spores, gaseous and mineral contaminants that can cause respiratory inflammation in susceptible individuals. The frequency of these events is expected to increase in the next century as precipitation levels vary due to elevated global temperatures. Similarly, high temperatures and arid environments are associated with an increased frequency of wildfires. The total area burned by wildfires in the western U.S. doubled between 1984 to 2015, secondary to the effects of climate change and fire suppression [63]. Wildfires are increasingly making media headlines, creeping closer to suburban areas, displacing thousands of individuals and exposing thousands of others to toxic levels of chemicals including hydrocarbons, carbon monoxide, particulate matter, carcinogens and respiratory irritants [64]. Wildfires contribute to multiple adverse health effects, from acute injuries, burns and smoke inhalation to the more chronic effects of wildfire smoke, with firefighters and emergency responders disproportionately impacted. Exposure is associated with multiple adverse cardiopulmonary health effects, similar to particulate air pollution, including reduced lung function, asthma exacerbations and acute cardiovascular events [65, 66].

Increase in Natural Disasters and Resurgence of Zoonotic Diseases

The occurrence of other natural disasters – including hurricanes, tornadoes, and floods – also increased in recent decades, linked to climate change [67]. Affecting water supplies and sanitation systems, natural disasters can have profound effects on the communities they affect and cause great disruptions to established infrastructures and habitats, including threatening water supply. Workers involved in disaster response and emergency rescue are at increased risk of injury and illness through exposure to chemical and infectious hazards present within these unstable environments and associated psychological conditions due to the stressful nature of the recovery work.

There are also concerns that the effects of changing seasonal patterns on vector habitats/reservoirs will cause a resurgence of zoonotic infectious diseases in endemic areas [68]. Studies have shown associations between meteorological factors (temperature, precipitation, flooding) and increases in vector-borne diseases, in addition to other food-borne and water-borne infections, including cholera, schistosomiasis, salmonella and E.coli, with emergency responders and clean-up workers at particular risk. Previous extreme weather events and flooding have also been associated with outbreaks [69-71]. Alterations in the ecosystem can also lead to a loss in biodiversity and further imbalances. These situations must be monitored regularly to protect working populations in agriculture, sanitation, animal husbandry, and fisheries who are more susceptible to pathogenic bacteria exposure due to the nature of their work.

Future Recommendations

Climate change threatens the health and safety of numerous workers, especially those who work outdoors. Preventive action must include a comprehensive approach incorporating the nature of the work, the specific exposures, mitigation strategies, and the underlying health of the worker. Within individual workplaces, education to both employers and employees must be provided regarding the potential risks and negative health consequences of working under such conditions. Workers should be closely monitored, especially those with pre-existing conditions including cardiovascular disease and respiratory disease who have increased risks associated with exposure to increasing temperatures and poor air quality. Providers must be trained to recognize and respond as hazards develop, and policies and procedures must be re-evaluated regularly to ensure sustainability, safety and effectiveness.

While alterations in workplace behaviors, including reduced work hours and increased rest periods during peak heat times, help to manage risks associated with heat stress, primary efforts must focus on the driving source: climate change. Response planning must be multidisciplinary, including representatives from workers, employers, the health sectors, the community, and government to ensure a comprehensive, effective approach. Multidisciplinary research and educational components are also needed to better understand, predict and communicate the impact of future hazards associated with climate change and mitigation strategies. Sustained access to critical resources (e.g. health care, water, food) and the protection of response workers responsible for providing assistance must be addressed.

As the future moves towards technology that supports greener energy, stakeholders must also remain vigilant towards the potential effects of new exposures. Renewable energies may lead to a decrease in coal mining and fossil fuel related hazards; however, the integration of solar and wind energies introduces new possible exposures including cadmium telluride, gallium arsenide and photovoltaic panels, which warrant close monitoring of exposures and surveillance of at risk workers and communities.

HOW TO BETTER PROTECT WORKERS IN THE FUTURE

Occupational safety and health face several challenges related to the rapid societal, technological, economic, and employment-related changes that characterize the Fourth Industrial Revolution. Protecting future worker health and well-being will require multiple initiatives, summarized in Table 2. These include better-integrated databases, greater investment in of occupational health research and education, enforceable regulations, and new preventive strategies.

Table 2 Selected priorities for better worker protection in the 21st century.

The current status of occupational health surveillance and data collection in the U.S. is inadequate to meet the needs of the future and will need to adapt to capture changing work structures and hazards, including variables introduced by flexible work, multiple jobs held at one time, as well as periods of unemployment. Given the fragmentation of the workforce that has occurred, innovative approaches to reach workers for participation in surveillance are needed. Preliminary efforts are underway to incorporate occupational information into electronic health records but are not widespread [72]. NIOSH has drafted an information model of Occupational Data for Health, so the information captured is useful both for primary care physicians as well as public health. These approaches must also help fill data gaps that exist for vulnerable workforces and occupational health disparities in general [19].

NIOSH has also utilized machine learning to rapidly code large data sets of Workers’ Compensation claims, speeding up a process that would otherwise take years [11]. This is a promising application of artificial intelligence to occupational health research. Artificial intelligence also has the potential to revolutionize the field of exposure assessment: artificial intelligence-enabled sensors could improve surveillance of occupational health effects through the formation of 24/7 sensor networks and algorithm-driven data analysis. Such advances will be necessary to assess the impact of novel work exposures and the effects of mixed exposures (in contrast to traditional analysis of one exposure at a time) and interactions between work and environmental exposures.

Greater investment in occupational safety and health training and regulatory programs is also needed. In its 50-year history, OSHA has been able to enact only a small number of new or revised standards, in large part due to industry opposition. There is no substitute for clear workplace safety standards and enforcement. Federal, state, and local agencies entrusted with public health and safety need greater support and resources to meet current needs, not to mention those that are anticipated in the future.

Programs in industrial hygiene, occupational medicine, and occupational health nursing within the U.S. have experienced a decline in funding and are attracting a decreasing number of trainees and supporting faculty [20]. Investment in multidisciplinary occupational health research and educational programs is needed to develop future occupational health practitioners, educators, and researchers. Partnering with community-based organizations, industry, workers, and labor unions will improve education on worker health and safety issues and increase knowledge through collaborative projects.

Occupational safety and health increasingly require consideration of the full range of work factors that contribute to overall well-being, in contrast to the traditional focus on recognizing and managing specific physical and chemical hazards. The nature of workplace exposures has changed over time and will continue to change with technological advancement, as well as flexible and precarious work. Psychosocial hazards have taken on an added importance, as work has become increasingly digitalized and flexible. Strategies to prevent and reduce stress-related disease will need to take their place alongside PPE and engineering controls as hallmarks of the field.

The health of the workforce is determined by both work and non-work risk factors, and the field is expanding to reflect this. NIOSH’s Total Worker Health exemplifies a new, holistic approach to occupational safety and health that aims to integrate