Health hazards to park rangers from excessive heat at Grand Canyon National Park

Wilderness First Responder Medical Clearance - A Scoping Review with Recommendations

BACKGROUND AND PURPOSE

Due to environmental extremes, as well as the nature of the work itself, wilderness first responders are at risk of incurring medical events in the line of duty. There currently do not exist standardized and scientifically supported methods to screen for a wilderness first responder's risk of incurring a medical event.

METHODS

We performed multiple scoping reviews using PubMed and CINAHL. The reviews covered six medical screening criteria based on previous recommendations from the National Fire Protection Association (NFPA) and the US Forest Service, and we grouped our reviews into two categories: articles that addressed objective screening criteria, and articles that addressed subjective findings with the first responder.

RESULTS

Of the objective criteria, our reviews identified 21 articles addressing the ability to screen for risk of incurring a medical event by evaluation of a first responder's heart rate, 12 by blood pressure assessment, and 56 by assessment of body temperature. Of the subjective criteria we identified 19 articles focused on self-assessment, 34 articles on the use of standardized tools to assess for fatigue and sleepiness, and two articles on assessment of a first responder's urine to determine level of dehydration. We also identified seven additional articles through a hand search. Overall, there were 151 articles identified in our scoping reviews. These articles were largely of low quality, consisting mostly of case series without comparison groups.

CONCLUSION

There is a dearth of high-quality research into the medical assessment of first responders. We recommend that this paper, and measures discussed within it, be used as a starting point in the development of an evidence-based assessment protocol for wilderness first responders. We also recommend the development of a national database of medical events incurred by wilderness first responders to facilitate higher-quality research of screening protocols in this community.

Beyond "bluespace" and "greenspace": A narrative review of possible health benefits from exposure to other natural landscapes

Numerous studies have highlighted the physical and mental health benefits of contact with nature, typically in landscapes characterized by plants (i.e., "greenspace") and water (i.e., "bluespace"). However, natural landscapes are not always green or blue, and the effects of other landscapes are worth attention. This narrative review attempts to overcome this limitation of past research. Rather than focusing on colors, we propose that natural landscapes are composed of at least one of three components: (1) plants (e.g., trees, flowering plants, grasses, sedges, mosses, ferns, and algae), (2) water (e.g., rivers, canals, lakes, and oceans), and/or (3) rocks and minerals, including soil. Landscapes not dominated by plants or liquid-state water include those with abundant solid-state water (e.g., polar spaces) and rocks or minerals (e.g., deserts and caves). Possible health benefits of solid-state water or rock/mineral dominated landscapes include both shorter-term (e.g., viewing images) and longer-term (e.g., living in these landscapes) exposure durations. Reported benefits span improved emotional and mental states and medical treatment resources for respiratory conditions and allergies. Mechanisms underlying the health benefits of exposure consist of commonly discussed theories in the "greenspace" and "bluespace" literature (i.e., instoration and restoration) as well as less discussed pathways in that literature (i.e., post-traumatic growth, self-determination, supportive environment theory, and place attachment). This is the first review to draw attention to the potential salutogenic value of natural landscapes beyond "greenspace" and "bluespace." It is also among the first to highlight the limitations and confusion that result from classifying natural landscapes using color. Since the extant literature on natural landscapes - beyond those with abundant plants or liquid-state water - is limited in regard to quantity and quality, additional research is needed to understand their restorative potential and therapeutic possibilities.

An international scoping review of rangers’ precarious employment conditions

Protecting wildlife and other natural resources requires engaging and empowering local communities, ensuring compliance with rules, and ongoing monitoring and research. At the frontline of these efforts are rangers. Despite their critical role in maintaining the integrity of parks and protected areas, rangers across the world are exposed to precarious employment conditions and hazardous work environments. We conducted an international scoping review to understand which employment and working conditions are examined in the context of the ranger occupation and to assess whether the concept of precarious employment is used in the conservation, criminological, and environmental sustainability literature on rangers. We reviewed publications from Web of Knowledge, Scopus, ProQuest, and Medline, and grey literature for relevant English language articles published between 2000 and 2021. Our findings are based on the analysis of 98 included studies. We found that the most commonly discussed aspect of rangers’ employment and working conditions was the hazardous social and physical work environment, although this was often accompanied by severe income inadequacy, employment insecurity, and a lack of social security, regulatory support, and workplace rights. Such employment and working conditions can cause adverse impacts on rangers’ mental and physical health, well-being, and safety, and are also detrimental to their ability to adequately protect biodiversity. We conclude by outlining the need for sustainable solutions and additional research based on established conceptualizations of the precarious employment concept and other related concepts. Lastly, we suggest that governments should acknowledge the importance of rangers through their recognition as essential workers and provide greater support to improve their employment conditions.

Occupational heat exposure and the risk of chronic kidney disease of nontraditional origin in the United States

Occupational heat exposure is linked to the development of kidney injury and disease in individuals who frequently perform physically demanding work in the heat. For instance, in Central America, an epidemic of chronic kidney disease of nontraditional origin (CKDnt) is occurring among manual laborers, whereas potentially related epidemics have emerged in India and Sri Lanka. There is growing concern that workers in the United States suffer with CKDnt, but reports are limited. One of the leading hypotheses is that repetitive kidney injury caused by physical work in the heat can progress to CKDnt. Whether heat stress is the primary causal agent or accelerates existing underlying pathology remains contested. However, the current evidence supports that heat stress induces tubular kidney injury, which is worsened by higher core temperatures, dehydration, longer work durations, muscle damaging exercise, and consumption of beverages containing high levels of fructose. The purpose of this narrative review is to identify occupations that may place US workers at greater risk of kidney injury and CKDnt. Specifically, we reviewed the scientific literature to characterize the demographics, environmental conditions, physiological strain (i.e., core temperature increase, dehydration, heart rate), and work durations in sectors typically experiencing occupational heat exposure, including farming, wildland firefighting, landscaping, and utilities. Overall, the surprisingly limited available evidence characterizing occupational heat exposure in US workers supports the need for future investigations to understand this risk of CKDnt.

Observational Study of Grand Canyon Rim-to-Rim Day Hikers: Determining Behavior Patterns to Aid in Preventive Search and Rescue Efforts

INTRODUCTION

Grand Canyon National Park has seen an increase in visitors traversing the canyon from rim to rim (R2R) in a single day. R2R hikers travel over 33.8 km (21 mi) over 3300 m (11,000 ft) of elevation change and endure large temperature changes. Grand Canyon emergency medical service providers provide emergency medical services to over 1100 visitors annually. Direct guidance by Preventive Search and Rescue rangers has improved safety. The objective of this study was to examine visitors attempting an R2R traverse and to enhance PSAR rangers' anticipatory guidance.

METHODS

We conducted an observational study of R2R hikers in the spring and fall of 2015. Hikers consented to study inclusion and were interviewed at the starting trailhead, canyon bottom, and exit trailhead. We performed a survey and collected biometric data.

RESULTS

We enrolled 617 visitors with a median age of 43 y (interquartile range [IQR] 33-53); 65% were male and 46% had hiked the R2R a median number of 3 times previously (IQR 2-7). Hydration strategies included water bottle only (20%), hydration bladder only (31%), and both water bottle and hydration bladder (48%). R2R crossers had an average start time of 0530 (SD 1.3 h) and median crossing time of 11.9 h (IQR 10.7-13.3). Crossing time and self-reported fatigue were negatively correlated with prior R2R experience (P=0.02).

CONCLUSIONS

Crossing R2R in a day is hazardous and associated with risk of injury and illness. The results of this study can be used by Preventive Search and Rescue to reduce these risks by educating hikers.

Impact of climate change on occupational health and productivity: a systematic literature review focusing on workplace heat

Background:

With climate change, mean annual air temperatures are getting hotter and extreme weather events will become more and more common in most parts of the world.

Objectives:

As part of the EU funded project HEAT-SHIELD we conducted a systematic review to summarize the epidemiological evidence of the effects of global warming-related heat exposure on workers’ health and productivity.

Methods:

Three separate searches, focused, respectively, on: i) heat-related illness (HRI), cardiovascular, respiratory and kidney diseases; ii) traumatic injuries; and iii) vector-borne diseases or vectors distribution, were conducted in PubMed. EMBASE was also consulted to retrieve relevant studies focused on the health effects of climate change. A fourth search strategy to assess the effects on work productivity was conducted both in PubMed and in the SCOPUS database.

Results:

A significant proportion of studies reported findings regarding the Mesoamerican nephropathy issue. This is a disease occurring especially among young and middle-aged male sugarcane workers, without conventional risk factors for chronic kidney disease. For injuries, there is a reversed U-shaped exposure-response relationship between Tmax and overall daily injury claims. Outdoor workers are at increased risk of vector-borne infectious diseases, as a positive correlation between higher air temperatures and current or future expansion of the habitat of vectors is being observed. As for productivity, agriculture and construction are the most studied sectors; a day with temperatures exceeding 32°C can reduce daily labour supply in exposed sectors by up to 14%.

Conclusions:

The present findings should inform development of further research and related health policies in the EU and beyond with regard to protecting working people from the effects of workplace heat during climate change.

On the identification and interpretation of human skin spectral responses under adverse environmental conditions

The identification and interpretation of skin spectral responses play a central role in a wide range of biomedical engineering applications, from the noninvasive assessment of human health parameters to the location of individuals in distress during search and rescue operations. In this paper, we investigate the sensitivity of these responses to physiological changes triggered by adverse environmental conditions. Our findings, which are supported by predictive computer simulations and experimental observations reported in the scientific literature, indicate that the resulting variations of skin reflectance can be substantial. Accordingly, if not properly taken into account, they may considerably impair the efficacy of systems designed for the detection and analysis of skin signatures within and outside the visible spectral region.

The epidemiology of occupational heat exposure in the United States: a review of the literature and assessment of research needs in a changing climate

In recent years, the United States has experienced record-breaking summer heat. Climate change models forecast increasing US temperatures and more frequent heat wave events in the coming years. Exposure to environmental heat is a significant, but overlooked, workplace hazard that has not been well-characterized or studied. The working population is diverse; job function, age, fitness level, and risk factors to heat-related illnesses vary. Yet few studies have examined or characterized the incidence of occupational heat-related morbidity and mortality. There are no federal regulatory standards to protect workers from environmental heat exposure. With climate change as a driver for adaptation and prevention of heat disorders, crafting policy to characterize and prevent occupational heat stress for both indoor and outdoor workers is increasingly sensible, practical, and imperative.

Exertional heat-related illnesses at the Grand Canyon National Park, 2004-2009

BACKGROUND

The Grand Canyon National Park has approximately 4 million visitors between April and September each year. During this period, outdoor activity such as hiking is potentially hazardous owing to extreme heat, limited shade, and steep, long ascents. Given the high visitation and the public health interest in the effects of extreme heat, this study calculated morbidity rates and described heat-related illness (HRI) among visitors.

METHODS

We conducted a retrospective cross-sectional study from April 1 through September 30, during 2004-2009. From a review of Ranger Emergency Medical Services (EMS) incident report files, we extracted information on those that met the case definition of greater than 1 hour of outdoor heat exposure with an HRI assessment or diagnosis, HRI self-report, or signs or symptoms of HRI without another etiology noted. Visitor and temperature data were obtained from respective official sources.

RESULTS

Grand Canyon EMS responded to 474 nonfatal and 6 fatal HRI cases, with the majority (84%) being US residents, 29% from Western states. Of the nonfatal cases, 51% were women, the median age was 43 years (range, 11-83 years), and 18% reported a cardiovascular condition. Clinical HRI assessments included dehydration (25%), heat exhaustion (23%), and suspected hyponatremia (19%). Almost all (90%) were hiking; 40% required helicopter evacuation. The highest HRI rates were seen in May.

CONCLUSIONS

HRI remains a public health concern at the Grand Canyon. High-risk evacuations and life-threatening conditions were found. Majority were hikers, middle-aged adults, and US residents. These findings support the park's hiker HRI prevention efforts and use of park EMS data to measure HRI.