Above: Smoky conditions on the Legion Lake Fire in Custer State Park in South Dakota, December 12, 2017. Photo by Bill Gabbert.
Originally published at 6:02 p.m. MT, February 6, 2018.
After collecting data from wildland firefighters in the field, a group of researchers concluded that firefighters’ exposure to smoke can increase the risk of mortality from lung cancer, ischemic heart disease, and cardiovascular disease. In this first section we cover what is in vegetation fire smoke, and after that we have details about the additional mortality risk faced by firefighters who can’t help but breathe the toxic substances.
What is in the air that firefighters breathe?
There have been many studies about smoke dating back to the 1988 NIOSH project at the fires in Yellowstone National Park. Most of them confirmed that yes, wildland firefighters ARE exposed to smoke and in most cases they quantified the amount.
In 2004 Timothy E. Reinhardt and Roger D. Ottmar found a witches’ brew of methyl ethyl bad stuff that firefighters are breathing. All of these are hazardous to your health:
- Aldehydes (volatile organic compounds); can cause immediate irritation of the eyes, nose, and throat, and inhalation can cause inflammation of the lungs. Short-term effects include cough, shortness of breath, and chest pain. The most abundant aldehyde in smoke is formaldehyde. When formaldehyde enters the body, it is converted to formic acid, which also is toxic.
- Sulfur dioxide (SO²); causes severe irritation of the eyes, skin, upper respiratory tract, and mucous membranes, and also can cause bronchoconstriction. It forms sulfuric acid in the presence of water vapor and has been shown to damage the airways of humans.
- Carbon monoxide (CO); As CO is inhaled it displaces O2 as it attaches to red blood cells and forms COHb. COHb reduces the ability of the blood to carry oxygen and causes hypoxia (a condition in which the body does not receive sufficient oxygen). Due to their strenuous work, wildland firefighters often have increased respiratory rates, which will increase the amount of CO being inhaled when smoke is present. COHb has a half-life (the time it takes half of the COHb to dissipate from the body) of about 5 hours. Symptoms of CO exposure include headaches, dizziness, nausea, loss of mental acuity, and fatigue. Prolonged, high exposure can cause confusion and loss of consciousness
- Particulate matter; Respirable particulates are a major concern as they can be inhaled into the deeper recesses of the lungs, the alveolar region. These particles carry absorbed and condensed toxicants into the lungs
- Acrolein; may increase the possibility of respiratory infections. It can cause irritation of the nose, throat, and lungs. Long-term effects can include chronic respiratory irritation and permanent loss of lung function if exposure occurs over many years.
- Benzene; can cause headaches, dizziness, nausea, confusion, and respiratory tract irritation. Although the human body can often recover and repair damage caused by irritants, prolonged exposure from extended work shifts and poorly ventilated fire camps can overwhelm the ability to repair damage to genes and deoxyribonucleic acid (DNA).
- Crystalline silica; can cause silicosis, a noncancerous lung disease that affects lung function. But OSHA classifies it as a carcinogen.
- Intermediate chemicals; have been shown to cause a variety of health problems including bronchopulmonary carcinogenesis, fibrogenesis, pulmonary injury, respiratory distress, chronic obstructive pulmonary disease (COPD), and inflammation.
One of the more recent research efforts, from 2009 to 2012, was led by George Broyles of the U.S. Forest Service, National Technology and Development Program, in Boise, Idaho. They collected data in 11 fuel models in 17 states on initial attack, prescribed burns, and large project fires. The group measured carbon monoxide (CO) with electronic datalogging dosimeters and particulate matter using air pumps and filters.
Monitoring carbon monoxide (CO) can be important, and is also fairly easy to do and not terribly expensive. Researchers have found that it can be a surrogate for the primary irritants of concern in wildland smoke near the combustion source. If CO is present, it’s almost certain that the smorgasbord of nasty stuff is in the air.
Electronic CO monitors are available for $100 to $300. Another option is the little disposable CO monitors called diffusion tubes. With the holder they are about the size of a dry erase marker. Many are made by Drager, and for eight hours can record the cumulative CO. You can’t get an instantaneous reading, but the total hourly exposure can be monitored. They cost about $13 each. If one or two people on the crew carry them it can provide a heads up if the air quality is really bad.
What are the health effects of smoke exposure on a wildland fire?
Employers in most if not all workplaces are required to minimize hazards and provide a safe working environment. But of course it is impossible to totally eliminate all risks to firefighters. A cynic might assume that leadership in the wildland fire community may be hesitant to ask the question if they don’t want to hear the answer.
In spite of numerous studies confirming that yes, there is smoke where wildland firefighters work, there has been little in the literature that quantifies the effects on a person’s health. A new study published in August, 2017 contains a preliminary analysis addressing that question.
It is titled Wildland Fire Smoke Health Effects on Wildland Firefighters and the Public – Final Report to the Joint Fire Science Program. The authors are Joe Domitrovich, George Broyles, Roger D. Ottmar, Timothy E. Reinhardt, Luke P. Naeher, Michael T. Kleinman, Kathleen M. Navarro, Christopher E. Mackay, and Olorunfemi Adetona.
They used the field data collected in the 2009 to 2012 George Broyles study to extrapolate the physical and health effects on humans. The authors actually came up with numbers that indicate firefighters’ relative mortality risk for lung cancer, ischemic heart disease, and cardiovascular disease.
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