PB: the smoking gun.
ONE OF THE MAJOR CONCERNS ASSOCIATED WITH THE CURRENT FOREST-HEALTH SITUATION IN THE WESTERN UNITED STATES IS THE ALMOST-CERTAIN OCCURRENCE OF LARGE, INTENSE WILDFIRES ACROSS MUCH OF THE REGION. THE MAIN REMEDIES TO REDUCE THIS RISK, AS SUGGESTED BY FOREST ECOLOGISTS, INCLUDE THINNING OVERLY DENSE STANDS TO REMOVE EXCESSIVE FUELS, FOLLOWED WHERE POSSIBLE BY SLASH BURNING TO REDUCE WILDFIRE HAZARD AND RECYCLE NUTRIENTS.
On lands where fuel conditions allow a fire to burn without destructive impact on the forest or surrounding private lands and homes, one of the treatments proposed is a careful "prescribed" fire, intentionally or naturally ignited, that is allowed to burn so long as it stays within the prescribed limits of impact and damage.
Both the untreated situation, with its wildfires, and the treatment, with prescribed fires, will create a significant amount of smoke, and smoke is a public health problem that worries air quality regulators. In 1994 it was estimated that over 1.35 million tons of PM2.5 (particulate matter less than 2.5 microns in diameter) were emitted from 65,700 fires that burned 3.8 million acres of federal lands. Several communities, including Wenatchee, Washington, and Boise, Idaho, experienced smoke pollution well over Air Quality Standards adopted by the Environmental Protection Agency to protect public health.
Currently, the regulations associated with the Clean Air Act classify the smoke from prescribed burning as a "human-induced" pollutant, while the smoke from wildfires is a "natural" pollutant. The first has been regulated by EPA and the states; the second hasn't. That could change in the future, however, as implementation of the 1990 Clean Air Act Amendments proceeds. In this latest version, EPA was instructed by Congress to determine whether "natural" events such as wildfires may now be considered to be "human-caused" if people's actions have contributed significantly to their occurrence. With many wildlands so far outside their normal range of fuel-loading variability because of years of intentional fire-suppression activities, a reasonable case can be made that today's wildfires are at least in part "human-caused" and therefore subject to regulation under the Clean Air Act. Just what EPA would do to regulate them is not clear, but there are suggestions that the agency consider the total smoke pollution from both wild and prescribed fires, and seek to keep that total pollution within acceptable limits.
The result, according to some calculations, may be to limit prescribed fires even more than is the case today. In the face of the current forest-health situation, the Forest Service is proposing to increase prescribed burning by 30 percent a year over the next three years. Such increases clearly pose a conflict with air-quality regulations, which many land managers say already limit the amount of prescribed burning they can accomplish in any one year. Given the amount of forest that currently needs treatment to avoid catastrophic wildfire, many feel that it will be impossible to carry out the necessary prescribed burning and slash disposal under the current Clean Air restrictions.
This raises a major question: Are the current air-quality restrictions going to result in more or less human health impact? Is it possible that if the amount of prescribed burning is restricted, the nation will end up with more smoke and sick people from wildfire effects than would have occurred if the land treatment had been allowed? These questions are increasingly being asked by forest and air-quality managers alike, so AMERICAN FORESTS has posed the question to a wide variety of experts who are studying the situation. As you will see, the answers are far from clear, and the stakes are high.
First, it is important to recognize that the pollution associated with woodburning is a legitimate concern, and that people's health and lives are placed at risk by an increase in airborne soot, smoke, chemicals, and other particles. Major attention is now being paid to the very small particles of soot and chemicals produced by woodburning. These are particles smaller than 2.5 microns in diameter. (In comparison, a human hair is about 75 microns in diameter.) Because they are so very small, such particles can bypass the defenses in the respiratory tract and penetrate deeply into lung tissue. The EPA, which has focused its attention and regulatory limits on particles smaller than 10 microns (PM10 is the term commonly used), is now reviewing its regulations to determine if the present health standards should be revised to focus on the smaller, PM2.5 particles.
There is still controversy over how seriously airborne particles affect human health, because the precise cause-effect relationship still remains largely unknown. Increasingly, however, studies show a direct correlation between increases in airborne particulate matter and rates of school absenteeism, sickness, and death. In a 1993 study of six cities where data were available, and in a 1995 follow-up study tracking the health histories of over a half-million adults, Dr. Douglas Dockery of Harvard University and co-workers found that in cities with the highest PM2.5 pollution levels, people were 15-17 percent more likely to die prematurely than they were in the cleanest cities. This remained true even when such other factors as age, smoking history, other health problems, weather, and similar variables were taken into account.
In a separate study conducted in Logan, Utah, Dr. C. Arden Pope III, an environmental economist, discovered that school absenteeism could be directly correlated with the emissions of the valley's main source of particle pollution - a local steel mill. When the mill shut down for a year due to a strike, then started operating again, it provided an excellent basis for studying the correlation between school records, hospital records, and death statistics. Because the Utah area receives less pollution from other sources such as industry and automobiles than areas like Los Angeles or an industrial city in the Midwest or East, the research could focus more directly on a single source of pollution - small particles.
The Utah results show that children's breathing capacity goes down as particulate pollution rises. Adults suffer as well losing 3 percent of lung capacity for every rise of 100 micrograms of particles in a cubic meter of air. The researchers also found that death rates went up 16 percent for every additional 100 micrograms of airborne particles.
The research has policy analysts at EPA concerned, as a court-ordered review of Clean Air Standards moves ahead. "'We are certain to have to factor in the health hazards of PM2.5 during the next round of regulatory review," says Dr. Dwight Atkinson, chief of the Air Policy Branch in EPA's Office of Policy Analysis. "But the forest-health situation in the West raises an enormously complicated question about how to do this in a way that does not make a bad situation even worse."
His concern is shared by Dr. John Core, director of the WESTAR Council, an organization representing western state air-quality agencies. In a paper presented at a March 1995 scientific conference on prescribed fire in Tampa, Dr. Core noted that air-quality agencies are increasingly concerned about forest health. "Millions of people in western communities may be at serious health risk in the current wildfire situation," Core noted. "With PM10 levels already high from forest and agricultural burning in many areas, new concerns surfacing about the health effects of fine particles, and western interests wanting to prevent regional haze and visibility loss, the proposal to increase prescribed burning by a factor of two to 10 times causes considerable concern. On the other hand, the prospect of seeing intense wildfires that create even higher pollution levels is not an attractive option."
Core identities a question that, though it lies at the heart of the matter, may defy an accurate answer based on current science. "If forests are treated with prescribed fire and other forest-health treatments, will wildfire extent and severity really go down, and to what extent?" Though it is recognized that wildfires generate higher levels of particulate pollution per acre than prescribed fires because of higher fuel consumption, it is also true that the cooler, smoldering fires often associated with prescribed burning can create as much as twice the smoke per unit of fuel consumed. So, the tradeoff is not always clear.
Wildfires may, however, create far different pollution events that affect wider regions of the country. Nobody controls when or where wildfires occur, and today's fires often result in very high-intensity crown fires that create high-velocity winds within the fire storm. They may also burn during periods of windy weather, when the smoke can be carried hundreds of miles. In 1994, Forest Service researchers following the smoke plume from the Chicken and Corral fires near McCall, Idaho, were still measuring pollution at or near levels that would violate the federal clean-air standard near Missoula, Montana - more than 140 miles away. Depending on weather conditions, large wildfires can affect air quality over large regions.
Prescribed fires, on the other hand, are normally undertaken when weather and fuel conditions are such that smoke impacts on the public are likely to be minimized. But the impact of a large prescribed-fire program, as is being proposed in some forest regions where fuel conditions are a serious concern, might mean that wide areas of the West will see elevated smoke levels for longer periods of the year. The tradeoff, then, is between much higher average levels of smoke from prescribed fire or shorter-term but more severe wildfire smoke impacts.
The Forest Service is currently working to develop a computer model that can help evaluate the combined emissions from prescribed fire and wildfire under different levels of fuel treatment, and to help identify the amount of prescribed fire that might result in the lowest possible total of particulate emissions from wildlands. This effort may be useful in helping air-quality agencies establish regulations that encourage prescribed-fire levels that can both meet the forest health need and keep pollution levels minimized.
Forest managers point out, however, that a significant expansion of prescribed fire is not an easy task. The Forest Service estimates that it is currently able to treat about 430,000 acres by prescribed fire each year - only about one-quarter of one percent of the public land administered by the agency in the West. With many of the long-needled-pine ecosystems needing to be treated every 15-25 years, the current rates of treatment will need to be greatly accelerated. Even if clean-air restrictions are eased, the short periods of safe burning weather in spring and fall, coupled with the high risks and liability involved in a fire escape, mean that managers will continue to be cautious in their approach to using fire as a forest-management tool.
What is clear is that the forest-health situation, with its almost-certain increase in future air pollution from smoke (whether from wildfires, prescribed fires, or a combination of the two), comes at an awkward time for air-quality regulatory agencies. Under pressure from Congress and the public to reduce public health hazards, visibility losses, and other impacts of airborne pollution, they face the prospect that those problems may increase significantly in the next few decades, due to the pent-up fuels that are the legacy of a century of fire suppression in the West.
Atkinson and Core believe that the best solution today may be a concerted, cooperative effort by land-management and air-quality agencies to identify the highest-risk forest areas - in terms of wildfire hazard, pollution impacts, and other factors such as endangered wildlife, and job protection - and to mount an all-out forest-health-treatment program designed to minimize the risks. An exploratory effort has so far involved AMERICAN FORESTS and several federal agencies in discussions designed to create such an initiative.
"If we can come together on this issue," Atkinson says, "it may dispel the myth that forest managers and air-quality agencies are opposing each other. We're on the same side - we all want to see healthier forests, fewer destructive wildfires, less air and water pollution, and strong economies in forest communities. Our challenge is, how do we get there?"
NEIL SAMPSON - is senior vice president for science and policy at AMERICAN FORESTS.
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|Title Annotation:||prescribed burning|
|Date:||Jul 1, 1995|
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