Cardiovascular Risks of Wildland Firefighting
Brian J. Sharkey, Ph.D.
406-329-3989 (fax 3719)
Abstract†† Historical records of firefighter fatalities indicate that heart attacks have been a major contributor to the medical fatalities experienced by wildland firefighters. In recent years, three individuals have died while training for or taking a work capacity test designed to select firefighters. This paper outlines the cardiovascular risks associated with wildland firefighting, compares the risks of work capacity testing with those of firefighting, and considers ways to reduce the risks, including health screening, medical examinations, and reconsideration of the Incident Command System positions requiring the arduous level work capacity test.†††† Key words: Work capacity tests, health risk screening, medical examinations
(Paper delivered at the annual meeting of the International Association of Wildland Fire, Missoula, MT, 2001)
An analysis of the wildland firefighter fatalities occurring between 1990 and 1998 indicated that 29% were due to burnover, 24% to aircraft accidents, 21% to heart attacks, and 18% to vehicle accidents. The remaining fatalities were due to falling snags (4%) and miscellaneous causes (4%). Further analysis indicated that deaths from heart attack were higher for volunteers (42%) than for federal or state firefighters (15 and 11% respectively)(Mangan 1999). An analysis of firefighter fatalities from 1910 to 1996 indicated that medical or sickness related fatalities accounted for 11% of all deaths, and that heart attacks were responsible for 90% of that total, or 10% of all firefighter deaths (NWCG 1997). Death from heart attack is all too common among wildland firefighters.
A heart attack or myocardial infarction occurs when the flow of blood in the coronary arteries is severely restricted, robbing the heart muscle of needed oxygen. The underlying cause, atherosclerosis, is a process that deposits scale-like plaque within the artery, eventually restricting the flow of blood, or sloughing off plaque to form a clot. Atherosclerosis is a disease that begins in childhood. Hearts of deceased teenagers have been shown to exhibit varying degrees of coronary narrowing, as have the hearts of autopsied young soldiers. Heart disease is the major cause of death for men and women. It begins early and develops at a rate that depends on the influences of heredity and behavior, including diet, weight control, cigarette smoking, and physical activity.
This paper outlines the cardiovascular risks associated with wildland firefighting, compares the risks of work capacity testing with those of firefighting, and considers ways to reduce the risks.
Risks of Firefighting†††
Analysis of mortality data for structural firefighters indicates heart-related death rates similar to or slightly above population values. There was no evidence of an association between the occupation of firefighting and increased risk of overall mortality, mortality from all cancers combined, or from lung cancer (Baris et al. 2000). Data for wildland firefighters indicate higher cardiovascular risks for volunteers than for federal or state firefighters. One possible reason for the difference is that federal and many state agencies annually administer work capacity tests that encourage the maintenance of physical fitness. Few municipal and volunteer departments have mandatory annual testing. However, several test-related fatalities have led to a reexamination of the work capacity tests, the procedures for test administration, and the types of positions that require the arduous level of testing.
The Pack Test (PT) is the work capacity test used by federal agencies to determine fitness for duty. It consists of a 3-mile (4.83-km) hike with a 45-pound (20.5-kg) pack over level terrain. The test emerged from a process that included a job task analysis, laboratory studies, and then extensive field trials. The test is based on an actual job task that is highly correlated to other firefighting tasks. The energy expenditure of the test is similar to that encountered on the job (7.5 kcal/min). The duration of the test reflects the ability to sustain the effort for prolonged periods of work. The test does not have an adverse impact on women or minorities, nor does it discriminate according to age, height, or weight. Pass rates on the test exceed 90% in the United States, Canada, and Australia (Sharkey 1999).†
Because the PT replicates a portion of the job of firefighting, and because performance on the test is highly correlated with other firefighting tasks, its risks could be considered similar to the job itself. It could be argued that the pressure and anxiety associated with taking the test might increase the cardiovascular risk. However, it is unlikely that this stress would exceed the stress of hiking over difficult terrain under adverse environmental conditions, or of moving to a safety zone during an emergency.† Since the adoption of the PT in 1998, three federal or state employees have died while taking the test. Over the period 1990 to 1998, 29 wildland firefighters died of heart attacks, an average of 3.2 per year. There were 3 in 1994 and 4 in 1996. During the 2000 fire season, the worst in 50 years, 2 heart-related firefighter fatalities were recorded, one on a fire and one during testing with the PT. The small number of heart fatalities during the 2000 season is remarkable considering the number of personnel deployed, the length and severity of the fire season, and the advanced age of retirees who returned to help during the severe fire season..
Population data indicate that approximately 10% (6-14%) of all heart attacks occur during exertion. This percentage agrees with the historical trend for heart-related deaths among wildland firefighters. Those most likely to experience an event are overweight males who smoke, have high cholesterol, and are physically inactive. Research indicates that physically inactive individuals are 56 times more likely to experience a problem during exertion (Thompson 2001). Other risk factors include a family history of heart disease, age (over 45 for men, 55 for women), hypertension, and diabetes.
Population data reveal the life-threatening risks of clinical exercise tests (1.59/10,000 hours) and screening exercise tests (1.06/10,000 hours). The 2000 fire season fatality associated with the pack test yields an estimated risk rate below 0.5/10,000. The risk of testing firefighters is less than half the population risk. During exercise training, the risk of death in apparently healthy individuals ranges from 0.01 to 0.2/10,000 hours (Foster and Porcari 2001). The two fatalities during the 2000 fire season yield an estimated risk rate of 0.00017/10,000 hours (based on 25,000 employees working 45 days of 10 hours per day). Thus the risk of exertion associated with wildland firefighting is a small fraction (one-one hundreth) of the risk associated with exercise training.
Fire personnel who died taking or training for the PT exhibited one or more of these cardiovascular risks. All were over 45 years of age, some were inactive or had only recently become active to train for the test, and some had medical conditions such as hypertension. One individual had experienced a previous myocardial infarction (heart attack) but was not screened before taking the test. Autopsies revealed evidence of underlying atherosclerosis. Two individuals had visited a physician before taking the PT. Only one of the fatalities was likely to be a line-going firefighter. What measures can be taken to reduce the risks of death during testing or firefighting?
Twenty-two incident command positions call for the arduous category test (PT); of these, only two include the actual firefighting duties for which the test was devised. The National Wildfire Coordinating Group (NWCG) Safety and Health Working Team (SHWT) has begun a review of line-going positions to determine which positions should require the arduous category and test. Other approaches to risk reduction include health screening, medical examinations, and risk† reduction.
Health Screening†† The American Heart Association (AHA) and the American College of Sports Medicine (ACSM) recommend a health-screening questionnaire (HSQ) designed to identify the small number of individuals who should seek medical advice before becoming involved†† in moderate physical activity (www.americanheart.org). Answers to simple health questions indicates oneís suitability for involvement in an exercise test or moderately vigorous training. Candidates for fitness training, firefighting, and field work should complete the HSQ before beginning strenuous training or taking a work capacity test (Table __).
The HSQ evaluates cardiovascular risk with questions concerning age, smoking, blood pressure, cholesterol, weight, family history, and physical activity. The questionnaire is designed to identify those in need of further medical review. A medical exam may be recommended for individuals over 45 years of age who have one or more heart disease risk factors, those who have been inactive, or those for whom the test, training, or work represents a significant increase in physical activity. For many others, the HSQ provides assurance of the readiness to engage in training, work, or a job-related work capacity test. For apparently healthy adults, the HSQ substantially reduces the risk of taking exercise tests or training, while significantly reducing the costs associated with medical examinations in a low-risk population. Studies in industry and sport indicate that health-screening questionnaires identify the risk factors and problems that call for further medical review.
Medical Exams††† The Federal Fire and Aviation Leadership Council, composed of fire management leaders from five federal land management agencies, accepted draft medical standards for arduous firefighting duties developed by an interagency committee. The medical standards are intended to help the examining physician, the agency personnel officer, and the medical review officer determine whether medical conditions may hinder an individualís ability to safely and efficiently perform the arduous work requirements of wildland firefighting without undue risk to himself/herself or others. The standards are subject to interpretation by a medical review officer (MRO) who has knowledge of the job requirements and environmental conditions in which employees must work.
The medical standards are intended to address health and safety issues, to improve medical surveillance, and to reduce job-related injuries. The initial medical exam involves a medical history, physical examination, vision, hearing, blood, and other tests (chest x-ray, resting EKG, and pulmonary function). The plan calls for subsequent examinations every 5 years until the age of 45, then every 3 years thereafter. The draft medical standards will be field tested in select locations during the 2001 fire season.††
Medical examinations are costly, time consuming, and - based on Australian experience with medical examinations - likely to disqualify about 3-7% of current firefighters. A time-consuming appeals process will reinstate some employees with previous experience. Others will have to seek additional medical tests at their own expense. The medical tests (e.g., EKG) will yield a percentage of false positive results, leading to additional testing and expense. Because the need for medical examinations increases with age, firefighters should receive a medical examination at age 45 and every 3 years thereafter. A health-screening questionnaire such as that recommended by the American Heart Association is adequate for fire personnel younger than 45.
The National Fire Protection Association (NFPA) has long had a standard on medical requirements for municipal firefighters (NFPA 1582). Yet these firefighters continue to have a high rate of heart-related deaths. Medical examinations do not eliminate the risk of heart attack. The NFPA does not have a mandatory annual standard for fitness and work capacity.
††††††††††† Lack of Activity†† In 1993 the American Heart Association listed lack of physical activity as one of the major risk factors for cardiovascular disease, along with cigarette smoking, hypertension, and elevated blood cholesterol. Regular physical activity has been proven to substantially reduce the risk of heart disease and cardiac death. The reduction in risk ranges from 30% for moderately active individuals to 70% for those who habitually engage in vigorous activity. A year-round program of physical fitness is recommended for those who intend to perform arduous work associated with wildland firefighting. The regular activity also serves to help control weight, hypertension, and blood cholesterol levels.
††††††††††† Weight Control††† With 61% of its population overweight or obese, the United States is experiencing an epidemic of excess weight (CDC 2001). The epidemic is due to an increase in caloric intake and a decrease in caloric expenditure. The consequences include increased rates of heart disease and diabetes, and billions of dollars in health care costs. Exercise and diet combine to provide effective control of body weight.
††††††††††† Hypertension †††High blood pressure increases the workload of the heart and its need for oxygen during exertion. Individuals with elevated blood pressure may exhibit an exaggerated blood pressure response to exertion, thereby increasing the risk of a heart problem. The exaggerated increase in blood pressure, along with the elevated heart rate associated with a low level of fitness, increase the work and oxygen needs of heart muscle. If the coronary arteries are narrowed, the muscle may experience the pain of ischemia or lack of oxygen. Excess weight is associated with elevated blood pressure and low levels of fitness.†
††††††††††† Cholesterol† ††High levels of serum cholesterol are associated with an increased risk of heart disease. The risk is associated with levels of low-density lipoprotein cholesterol (LDL-C) and inversely related to high-density lipoprotein cholesterol (HDL-C). Diet and exercise can lower LDL-C and raise HDL-C, reducing cardiovascular risk. Diet and exercise also lower serum triglycerides, another lipid related to heart disease risk. Coronary arteries are gradually narrowed by the deposition of plaque, a scale consisting of† LDL cholesterol and other debris. Some plaque is soft and more easily dislodged, capable of causing a clot that interrupts the flow of blood to the heart. Heavy physical exertion, along with an increased heart rate, blood pressure, and hormones (e.g., epinepherine), may disrupt vulnerable plaque and trigger an acute myocardial infarction or heart attack. At present, no readily available test can identify those with plaque deposits that may leave them especially vulnerable to a heart attack..
Alternative Tests††† Several other approaches to risk reduction have been suggested. They include alternatives to the work capacity test, such as a medically administered test, or a less strenuous predictive test. This approach has been recommended as a reasonable accommodation for older workers and those with joint problems. This approach presents several problems. An alternative test will lead to two classes of employees, those who meet the established standard and those who meet a modified standard. Will someone who cannot complete the PT on level terrain be able to negotiate the difficult terrain of a fire? This approach is certain to invite legal challenges, both during the hiring process and after injuries or fatalities occur.
Use of a medically-administered work capacity test assumes a test development and validation process at least as rigorous as that employed to develop the PT. The test will not be job-related, and it will lack important muscular fitness information and extensive data correlating performance on the test to firefighting tasks. Test reliability and objectivity will be difficult to ensure, and the cost of testing will be high. For these and other reasons an alternative test is not recommended. Other approaches can reduce the risks substantially.
A careful evaluation of the ICS positions that currently require the arduous test may reduce the number of positions and the cardiovascular risk. Finally, it is possible that some†† test-related fatalities may have occurred in the absence of any work capacity test. The exertion of fire duties could trigger an event, as could an the stress of an emergency operation or escape to a safety zone, when responding to the heart attack could slow escape and endanger the lives of coworkers.
There is no cost-effective way to guarantee heart health and suitability for arduous duty. No currently available test indicates the presence of vulnerable plaque, or the risk of heart attack. A medical examination, a resting EKG, or even a treadmill EKG (stress test) cannot guarantee heart health. Half of those who die of heart attacks and who had a recent stress test had a normal test (false negative test). For every 10 apparently healthy individuals who have an abnormal stress test, further testing will show that only one out of the 10 actually have a heart problem, the other nine do not (false positive test). False positive tests require expensive hospital-based follow-up to eliminate the concern (Neuburg 2000).††
Historical data on wildland fire fatalities indicate that about 10% of all deaths or 3.2 deaths per year have been due to heart attacks. The recent fatalities related to work capacity testing have not increased the historical rate. The risk of wildland firefighting and test-related fatalities can be reduced with health screening, medical examinations for those 45 years or older (or those indicated by the HSQ), and cardiovascular risk reduction. Risk-reduction strategies include year-round physical activity, weight control, attention to blood pressure and cholesterol. Careful review of the positions suitable for the arduous category could reduce the number of high-risk employees required to take the test.
The Medical Qualification Standards for Wildland Firefighters are intended to determine whether medical conditions may hinder an individualís ability to safely and efficiently perform the arduous work requirements of wildland firefighting without undue risk to himself/herself or others. However, evidence documenting the need for the standards has not been presented. There is no compelling evidence that visual, hearing, lung or other problems† endanger the health or safety of wildland firefighters. And the death rate of wildland firefighter from heart attacks is substantially below the rate for volunteer or municipal firefighters, or for the population at large.†
A comprehensive employee health/wellness program is a cost-effective way to provide periodic tests of blood pressure, cholesterol, and other tests indicated by age, family history or occupational exposure. The program also includes information and instruction on exercise, weight control, diet, stress reduction, and other factors associated with health. The program could be mandatory for fire personnel and voluntary for all others. The cost of the program could be met with the money saved by limiting medical examinations to those who actually need them, including individuals over 45 years of age and those identified by a health screening questionnaire.†
Baris, D. et al.† 2000.†† A cohort mortality study of Philadelphia firefighters. Fire Engineering, February.
Foster, C. and Porcari, J.† 2001.† The risks of exercise training. Journal of Cardiopulmonary Rehabilitation (in press, November).
Mangan, R. 1999.† Wildland Fire Fatalities in the United States 1990-1998. Missoula, MT: USDA Forest Service, Technology & Development Center.
Nuburg, J. 2000.† Cardiovascular Risk Assessment of BLM Wildland Firefighters over 40.† Unpublished paper presented to fulfill requirements of the MPH Degree Program in Occupational Medicine, College of Medicine, University of Arizona, Tucson.
NWCG 1997.† Historical Wildland Firefighter Fatalities 1910-1996. 2nd ed. Boise, ID: National Interagency Fire Center, NFES 1849.
Sharkey, B. 1999.† Development and validation of a job-related work capacity test for wildland firefighters. Paper presented at the meeting of the International Association of Wildland Fire, Sydney, AU.
Thompson, P.† 2001.†† The therapeutic role of exercise in modern cardiology. Paper presented at the meeting of the American College of Sports Medicine, Baltimore, MD.