Cardiovascular Risks of Wildland Firefighting
Brian
J. Sharkey, Ph.D.
406-329-3989
(fax 3719)
bsharkey@fs.fed.us
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)
Introduction
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 one’s 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 individual’s 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 individual’s 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.
References
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.
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P. 2001. The therapeutic role of exercise in modern cardiology. Paper
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