Breathless

By Robin Bible Tennessee Division of Forestry

Traditionally, breathing smoke on the fire line has been considered all in a day's work for wildland firefighters. Smoke is one of the many occupational risks that comes with the job, along with falling snags, breaking a leg, or worse, getting burned over. Researchers are just beginning to learn more about the serious health problems that can result from inhaling wildfire smoke.

When forest fuels burn, they discharge hundreds, if not thousands, of chemical compounds into the atmosphere, including carbon monoxide, total suspended particulates, hydrocarbons, nitrogen oxides and water vapor. “Through the detailed chemical characterizations of smoke, we find literally hundreds of compounds, many of these in very, very low concentrations,” says Darold Ward of the Forest Service's Fire Sciences Laboratory in Missoula, Mont.

The 1988 Yellowstone fires burned well over 1 million acres and provided the first opportunity to study a major wildfire smoke event. Concentrated smoke from the Yellowstone fires and others hung for weeks over Montana, Idaho and Wyoming, affecting the lives of thousands of residents and firefighters.

The following year, the National Wildfire Coordinating Group, the organizer of wildland firefighter activities for the U.S. Forest Service, National Park Service and Bureau of Land Management and Indian Affairs, launched a comprehensive risk-management study for determining the immediate and long-term effects of exposure to forest fire smoke. The Missoula Technology and Development Center, a fire research arm of the Forest Service, was asked to organize the study. “Interest in the health hazards of smoke intensified after the 1987 and 1988 fire seasons, which led us to develop a comprehensive plan to study emissions, employee exposure, health effects, risk assessment and risk management,” says the MTDC's Brian Sharkey.

Then came the fires of 2000 that burned over 7 million acres. In western Montana, smoke from numerous fires hung over mountain communities for several weeks, creating an eerie and choking fog. Streetlights came on in mid-afternoon and softball games and other outdoor activities had to be cancelled. Businesses relying on tourism lost millions of dollars, and air pollution alerts were common in many communities during this period.

With more people treated for smoke inhalation and other effects, this “smoke event” presented scientists and health researchers the opportunity to conduct a detailed study. The state of Montana asked the Centers for Disease Control and Prevention to determine if increases in respiratory and cardiovascular hospital admissions occurred during the last season's fires. The CDC compared 1999 and 2000 admissions records in four Montana counties: Ravalli, with the highest exposure to smoke; Missoula and Lewis and Clark Counties, with moderate exposure; and Yellowstone County, with the lowest exposure.

According to the study, hospital admissions for heart and lung ailments increased significantly at the height of the wildfire season, most notably in Ravalli County. Admissions for respiratory disease went from 8.6 per 10,000 residents in 1999 to 16.4 per 10,000 during the 2000 wildfire season — a 90% increase. Admissions for heart problems went from 22.1 per 10,000 residents to 34.6 — a 57% increase.

“Much remains to be studied about the long-term health effects of smoke from wildfires,” says Ann Acheson, the Forest Service's regional air quality officer in Missoula. “There's no doubt that the smoke is going to impact people, and they need to take the necessary precautions. What's unclear is when people are impacted with smoke for long periods, even weeks at a time. That's where additional research is needed.”

What is known is that over time, these smoke particles accumulate in the lungs and cause health problems — especially in people with congestive heart disease or lung diseases such as chronic obstructive pulmonary disease, emphysema or asthma. Obviously, those most affected are the elderly, children and smokers, along with those individuals who have existing respiratory and cardiovascular diseases.

During the 2000 wildfire season, large numbers of firefighters were required to seek medical attention for upper respiratory problems. “Breathing high smoke concentrations does expose those persons to toxic compounds contained in the smoke,” says Shannon Therriault, air quality specialist with the Missoula City-County Health Department.

“One of the greatest hazards in smoke lies in the particulate matter, a general term for that mixture of solid particles and liquid droplets found in air. Particulate from smoke tends to be very small, and as a result, is more of a health concern than the coarser particles,” Therriault said. “For example, the diameter of the average human hair is about 30 times bigger. These particles can build up in your respiratory system, causing a number of health problems, including burning eyes, runny noses, cough, headache and irritated sinuses. Long-term exposure, such as on the order of what firefighters experience, can impair lung function and possibly lead to cardiopulmonary disease and lung cancer.”

Studies have found that fine particulate matter, alone or with other pollutants, is linked to a number of significant respiratory and cardiovascular-related diseases. In addition, airborne particles are respiratory irritants and laboratory studies show that high concentrations of particulate matter cause persistent cough, phlegm, wheezing and physical discomfort in breathing. Particulate matter also can alter the body's immune system and affect removal of foreign materials like pollen and bacteria from the lungs.

Carbon monoxide, a colorless, odorless gas, is produced as a byproduct of incomplete combustion. Firefighters are exposed to large amounts of the gas in the smoldering stages of the fire, usually during the final mop-up stage. Carbon monoxide enters the bloodstream through the lungs and reduces oxygen delivery to the body's organs and tissues. The health threat from lower levels of carbon monoxide is most serious for those who suffer from cardiovascular disease. At higher levels, carbon monoxide exposure can cause headaches, dizziness, visual impairment, reduced work capacity and manual dexterity even in otherwise healthy individuals. At even higher levels seldom associated solely with a fire, carbon monoxide can be deadly.

Other hazardous air pollutants also are present in smoke, but in far less concentrations than particulate and carbon monoxide. According to Therriault, the most common are:

1. Acrolein

   An aldehyde with a piercing, choking odor that even at low levels, can severely irritate the eyes and upper respiratory tract causing stinging and tearing eyes, nausea and vomiting.

2. Formaldehyde

   Low-level exposure can cause irritation of the eyes, nose and throat. Higher levels cause irritation to spread to the lower respiratory tract. Long-term exposure is associated with nasal cancer.

3. Benzene

   Benzene causes headaches, dizziness, nausea and breathing difficulties and is a very potent carcinogen. The substance can cause anemia, liver and kidney damage, and cancer.

On the fire line, information collected by the MTDC from fire camp first-aid stations last summer indicated that 30 to 50% of first-aid visits were for upper respiratory problems such as colds, coughs and sore throats. Studies indicate that upper respiratory symptoms and problems increase over the course of the fire season. While upper respiratory problems may be due to smoke, they also may result from physical exhaustion, psychological stress and poor nutrition, all factors known to suppress the function of the immune system. The spread of these infections may be exacerbated by poor health habits and unhealthy conditions in fire camps.

Little is known about the long-term effects of smoke exposure on wildland firefighters. Several models, including cigarette smoking, urban air pollution and structural firefighting, have been used to infer possible risks.

It's been estimated that 80% of structural firefighters' injuries are due to smoke inhalation or oxygen deficiency and more than 50% of line-of-duty deaths are due to smoke exposures. During a structural fire, the carbon particles become coated with the chemicals released in the fire. The particles then carry the chemicals deep into the lungs. When firefighters exert themselves during the fighting stage of the fire, they breathe rapidly and deeply, increasing the amount of toxins inhaled.

Structural fires also can produce toxic chemicals such as polyvinyl chloride, which is used to make upholstery, wire, pipes and wall coverings. Burning pvc creates hydrogen chloride and phosgene. Polyethylene and pvc often are more dangerous when smoldering than during the high heat of a working fire, emitting carbon monoxide, hydrogen cyanide, hydrochloric acid and other chemicals.

Studies consistently fail to establish an increased risk of heart disease among structural firefighters. However, firefighters who smoke have been shown to have a greater risk of heart and pulmonary disease and lung cancer. “Pulmonary function changes and chronic lung disease have been shown in some studies of structural firefighters,” says Sharkey. “But, the effects have not been associated with years of service or exposure, suggesting greater effects in a small subgroup of workers.”

Days and weeks of smoke exposure can lead to more persistent health effects, including potential suppression of the immune system. Smoke can deaden the ciliary action that sweeps larger particles out of the respiratory tract for expectoration. Sharkey says that without this “ciliary escalator” to clean the lower respiratory tract, particles would slide deeper into the tract, causing congestion, coughing and other problems. “When such problems are combined with a suppressed immune system from stress, exhaustion and poor nutrition, the stage is set for bronchitis and a prolonged recovery,” Sharkey said.

According to studies conducted by the mtdc, mortality studies haven't been conducted to determine the long-term effects of exposure to forest fire smoke. The population of long-term wildland firefighters is limited, exposure data is nonexistent and potential exposure to other hazards, such as smoking, radon, wood burning and air pollution confounds the data. A fire manager who died of lung cancer was a long-time smoker; a retired firefighter recovering from open-heart surgery had a strong family history of the disease. Neither of these firefighter retirees spent much time on fires during their last 10 years of employment.

Roger Ottmar of the Forest Service's Pacific Northwest Research Station and Tim Reinhardt of the Radian Corporation conducted studies of employee exposure at prescribed and wildland fires. The research team fitted firefighters with sampling packs to collect breathing-air samples. The samples then were analyzed in the laboratory for respirable particulate, carbon monoxide, formaldehyde, acrolein, benzene and other toxic compounds. The researchers found that exposure to particulate matter, carbon monoxide and aldehydes was considerably less than they would have expected. Fewer than 5% of the firefighters studied were exposed to concentrations that exceeded exposure levels deemed permissible by OSHA, according to MTDC.

“Firefighters have a health risk at both wildfires and prescribed fires,” Ottmar says. “It's a risk that probably is less than some of the other risk threats they have out on the fireline, such as falling snags and getting hurt with the tools that they're using, and also driving on very narrow roads and hiking in very steep and rugged terrain.”

According to research scientists at the Smoke Management Coordination Air Program at the Forest Service's Northern Regional Office in Missoula, having access to accurate daily smoke forecasts can help managers plan their firefighting tactics. The ideal situation is to obtain good smoke dispersal. However, making sure that smoke disperses depends on a variety of factors working together, such as wind strength, atmospheric stability and the mixing depth above the surface.

The bad news is that those conditions that are usually ideal for smoke dispersal are usually not good for fighting fires. For example, strong winds that help move smoke out of a region also contribute to high erratic fire behavior, which makes control difficult. Unstable atmospheric conditions — the kind that produce thunderstorms — can also help smoke dispersion in the atmosphere.

What about respiratory protection? mtdc researchers have concluded that while respirators are feasible, this added protection for firefighters has not proved to be a viable option. One of the major concerns is in the reduction of work capacity. Respirators increase resistance to airflow, which also increases breathing resistance. Most healthy adults can use a respirator with an effectiveness of 95% without uncomfortable breathing resistance. However, heavy physical exertion on the fireline and working long hours at a physically demanding pace can lead to physiological stresses like increased respiratory and heart rates and heat stress. Also, mask use among those with cardiopulmonary and respiratory diseases can be dangerous and should only be used under a doctor's supervision.

Many firefighters have not been trained on how to use the masks properly and don't understand the importance of getting an airtight seal. To be effective, respirators must be able to filter out very small particles — around 0.3 to 0.1 microns — and provide an airtight seal around the firefighter's face. The best respirators are those with the purple HEPA as they offer the best protection, but are less comfortable.

Researchers and scientists agree that there are many inexpensive devices that can be implemented to immediately reduce the incidence of upper respiratory infection. Probably the most important thing that managers can do is to plan ahead and organize their fire, especially managed fires, in a way that keeps firefighters out of high-smoke concentration areas. If an individual firefighter is sensitive to the conditions that they're experiencing, they should take the common sense step of backing off a few feet, getting into a different location and using the natural conditions that are out there to put themselves in a better environment. The importance of good physical fitness, along with good personal hygiene and healthy behaviors, needs to be emphasized.

Robin Bible has 22 years of experience in wildland fire management and currently is the wildland operations manager for the Tennessee Forestry Division. He spent a portion of the summer of 2000 fighting fires and breathing smoke in Montana.

To minimize exposure to smoke:

• Locate camps and incident command posts in areas that are not prone to inversions.
• Reduce dust by watering roads at the incident, on drier roads leading to the incident, and in the base camp.
• Rotate personnel out of heavy smoke areas.
• Use flank attack as opposed to head attack, where appropriate, in heavy smoke situations.
• Minimize mop-up when possible.
• Use time and patience instead of water to put the fire out. Use burn piles and allow areas to burn themselves out. Rely on burn-up instead of mop-up.
• In heavy smoke situations, remove crews from the line when possible.

Health maintenance to reduce smoke exposure impacts:

• Monitor personnel for signs of fatigue and illness.
• Ensure firefighters are properly equipped for anticipated conditions (cold nights, rain, etc.).
• Provide for good rest and sleeping conditions.
• Encourage a high fluid intake during and after work for all personnel.
• Provide for adequate nutrition and supplements (e.g. antioxidants) if needed.
• Allow sick firefighters time to recover.
• Provide washing facilities near food lines and toilets.
• Limit close contact among firefighters by providing personal sleeping tents.
• Discourage sharing of canteens except in emergencies.
• Encourage personnel to cover their mouth and nose when they cough or sneeze to avoid the spread of infection.
• Segregate infected personnel when possible.
• Demobilize crews that have a large number of sick personnel.
• When symptoms are above the neck (stuffy nose, sneezing, scratchy throat), it's safe to continue to work if personnel continue to practice health maintenance tips mentioned above. If symptoms include fever, aching muscles, nausea, or diarrhea, hard work should be reduced or curtailed.

When symptoms are respiratory in nature — lung congestion, expelling of phlegm, chronic cough — it may be appropriate to reduce or curtail hard work. If symptoms persist and become severe, the medical unit leader should consult a qualified physician to determine the appropriate treatment, which may include a rest period in a clean air environment. This environment could include a nearby motel or fire camp that is smoke free or a school auditorium with a closed, filtered circulation system.

Montana Department of Environmental Quality
www.deq.state.mt.us/FireUpdates/index.asp

EPA/University of Washington Fire, Smoke and Health
www.firesmokehealth.org

National Weather Service
www.wrh.noaa.gov

National Wildland Fire Information
www.nifc.gov/information.html

Satellite Images of Fires
www.osei.noaa.gov/Events/Fires