There are few jobs that come attached with more peril than firefighting.
But the greatest threat to a firefighter's life may not be smoke or flames. It could be his or her heart.
Just ask Ronald Browne, a former 3-star chief with the New York City Fire Department.
Browne says his heart attack occurred when he was at home but still on duty. There were warning signs, he says -- but he ignored them until the pain was too intense to bear.
"Fortunately my wife is a nurse," he says. "My wife said I turned ashen gray. She recognized the symptoms of a heart attack, and she called 911 right away."
Browne was rushed to the hospital, where doctors treated him for his heart attack. He survived, but the episode led to his retirement from firefighting.
Now, a new study shows that episodes like Browne's may be more common than once believed, suggesting a tremendous increase in risk of death from heart attack and other cardiac emergencies for firefighters on the job.
"Although people have been discussing this issue for the past 30 years, there wasn't any scientific background on it," says lead study author Dr. Stefanos Kales of the Harvard School of Public Health.
Kales' study examined duty-specific risks of death from coronary heart disease among on-duty U.S. firefighters from 1994 to 2004.
What he and his colleagues discovered was that heart disease causes 45 percent of the deaths that occur among U.S. firefighters while they are on duty -- making it the most frequent cause of death in this dangerous profession.
The study, which appears in the current issue of the "New England Journal of Medicine", found that firefighters, while fighting a fire, experienced a risk of heart attack anywhere from 12 to 136 times as high as when they were engaged in normal day-to-day activities.
Their chances of heart-related death were also 2.8 to 14.1 times as high while responding to an alarm, 2.2 to 10.5 times as high while returning from an alarm, and 2.9 to 6.6 times as high during physical training.
Kales says the findings suggest that the psychological stress and physiological demands of some of the profession's most crucial tasks combines with other individual lifestyle factors to increase the risk of heart attack.
A Dangerous 'Workplace'
It's not the type of working environment that OSHA would smile about.
Raging blazes and blankets of sulfurous smoke set the stage for firefighters, often carrying more than 50 pounds of gear, to perform a wide array of demanding and dangerous tasks.
"Firemen have a job which appears to involve periods of exceedingly high physical demand and stress interposed with longer periods of relatively sedentary work," says Dr. Jeffrey Brinker, professor of medicine and radiology at Johns Hopkins University.
"There is little time to 'warm up.' In addition, the exposure to smoke may decrease the oxygen available for respiration."
All of these external hazards combine with the internal threat of psychological stress and adrenaline -- a "perfect storm" of sorts for a deadly heart attack.
"This fits with the data indicating that the major cause of death in athletes over 35 years old is coronary heart disease," says Dr. Doug Zipes. "So strenuous exertion in 'older' men, if it causes a fatality, that fatality is more likely to be due to coronary heart disease than other factors."
And the threat is more than just theoretical. Browne says that when he was a young lieutenant, he bore witness to the death of one of his fellow firefighters from a heart attack.
"He came out of the fire, sat on the back step of the truck and proceeded to have a heart attack," he recalls.
But off the job, there is little that sets firefighters apart from anyone else in terms of heart risk, as heart experts were quick to point out.
The study "shows that the relative risk of cardiac death is dramatically higher during fire suppression, alarm response and return to physical training compared to non-emergency duties," says Dr. P.K. Shah, Director of the cardiology and atherosclerosis research center at Cedars Sinai Medical Center. "But the study does not necessarily show an overall increased in cardiac death in firefighters compared to non-firefighters."
"It reconfirms that the absolute risk of cardiovascular death in firefighters is low, but that the relative probability is high during stressful activity," says Dr. Robert Myerburg, cardiologist at the University of Miami Medical School.
Heroes Experience Uncommon Stress
Some cardiac experts say the additional risks shown in the study underscore the importance of detecting heart problems early in firefighters who might defy the normal profile of someone at risk of heart disease.
"Firefighters are popularly viewed as young and physically fit, just the opposite of the profile we expect to be at heightened risk of cardiovascular disease," says Dr. Paul Underwood, past president of the Association of Black Cardiologists. "Yet the apparent stress of responding to a fire is reported as having measurable consequences."
Rich Duffy, director of occupational health, safety and medicine for the International Association of Fire Fighters (IAFF), agrees.
"The two largest risk factors for heart disease in the general public -- obesity and smoking -- are not big factors in the fire services," he says.
And sometimes the trauma of a particularly stressful event can linger on for years. Both of Browne's sons are chief officers with the FDNY, and both work in busy companies.
And both were part of the emergency units responding to the 9/11 attacks on the World Trade Center.
"During 9/11, their unit lost 12 men -- almost 50 percent of the unit -- which put them under a lot of stress," Browne says. "On 9/11, nothing in our experience prepared us for a building of that size collapsing in that way.
"That stress is always in the back of your mind, and that stress takes a toll."
Browne adds that firefighters face hazardous situations for a majority of their careers, which means that those with underlying heart problems could be gambling with their health for decades.
"For 20 to 25 years of your career as a firefighter, you are subjected to all of the hazards and stress that firefighting entails," he says.
"As a firefighter, you always want to do the right thing and do it to the best of your ability, but in the back of your mind there is always a nagging thought: Is this going to be the fire that I don't walk away from?"
Safeguarding Future Firefighters
Dr. Sanjeev Saksena, director of the Cardiovascular Institute and Arrhythmia/Pacemaker Service at the PBI Regional Medical Center Passaic, N.J., says more studies need to be done in order to determine the actual triggers for deadly heart attacks in firefighters.
However, he says the study represents a first step in learning how to prevent and deal with these episodes.
"It certainly gives room to pause and think of how we can improve outcomes," Saksena says, adding that the findings raise the point that "firefighters [should] be given protective medications before the actual events, and should there be medical help with them from the onset, among many other considerations."
Even more crucial may be measures that can be taken in order to deal with firefighters' underlying heart problems before they turn into a deadly situation.
"It seems important that fireman maintain physical conditioning throughout their working life -- and even thereafter," Brinker says. "In addition they should be screened for coronary risk factors."
Many of the preventive measures are already making their way into firehouses around the nation, Duffy says.
"We've been doing an awful lot," he says, adding that since 1997 the IAFF has pushed for all firefighters to receive an annual medical checkup.
"It's a hazardous job, but we do what we can to prevent not just traumatic injuries, but long-term diseases such as heart disease and cancer."
But Duffy adds that it is unlikely that the uncommon physical and psychological demands of the job will ever change.
"The actual physical stress of the job is an issue," he says. "I don't know how you resolve that. We try lots of interventions, but you're not going to end the 3 a.m. calls to a dangerous situation. That's just part of the angst that goes with it."
Browne says his biggest hope is that the current work done to help make firefighting as safe a job as possible will have benefits for his sons.
"I would hope that when they get my age, they don't have a heart problem," Browne says. "I hope that when they're 70 years of age, like I am now, their life expectancy will be better than mine."