These planes can release a tankful of bright pink flame retardant over a roaring flame in just 20 seconds. They have long been considered essential in fighting wildfires.
But new research shows that the millions of gallons of flame retardant sprayed onto landscapes each year to quell wildfires contain heavy metals and other chemicals that are harmful to human health and the environment. , has been shown to be associated with harmful burdens.
This toxicity poses a serious dilemma. These tankers and their cargo are powerful tools for putting out deadly fires. But as wildfires become more intense and more frequent in the era of climate change, firefighters are using them more frequently, releasing more harmful chemicals into the environment in the process.
Some environmental groups question the effectiveness and potential harm of retardants. Flame retardants are one of the intensive firefighting tactics used during large fires, so their effectiveness has been difficult to measure. Once the flames are extinguished, it's hard to take credit.
In recent years, the frequency and severity of wildfires has increased, particularly in the western United States. Scientists also found that fires across the region are growing faster than in recent decades.
There are also long-term health effects from exposure to wildfire smoke, which can penetrate the lungs and heart and cause illness. A recent global study on the health effects of air pollution from wildfires found that exposure to wildfire smoke has increased by 77% since 2002 in the United States. Globally, wildfire smoke is estimated to be responsible for up to 675,000 premature deaths per year. year.
Flame retardants pose a “very troubling trade-off” that further increases the burden on health and the environment, said Daniel McCurry, assistant professor of civil and environmental engineering at the University of Southern California, who led recent research on flame retardants. he said. -Metal content.
The U.S. Forest Service said Thursday that nine large retardant spray planes and 20 water cannon helicopters are being used to battle Southern California fires that have displaced tens of thousands of people. Several “water scooper” amphibious aircraft are also in use, which can skim the surface of the ocean or other bodies of water to fill tanks.
Two large DC-10 aircraft, dubbed “super-large air tankers” and capable of transporting up to 9,400 gallons of retardant, will also soon join the force, said Stanton, a spokesman for the National Interagency Fire Center in Boise, Idaho.・Mr. Florea said. It coordinates national wildland firefighting efforts throughout the West.
Florea said flame retardant sprayed before a fire coats the plants and prevents oxygen from burning them. (Red dye is added so firefighters can see the flame retardants against the landscape.) And flame retardants, which are typically made with salts such as ammonium polyphosphate, “last longer. . It doesn't evaporate like a drop of water,” he said.
But a new study by Dr. McCurry and his colleagues finds that at least four heavy metals in a common type of flame retardant used by firefighters exceed California's hazardous waste requirements. did.
Federal data shows that between 2009 and 2021, more than 440 million gallons of flame retardants were applied on federal, state, and private lands. Using that figure, researchers estimated that more than 400 tonnes of heavy metals were released into rivers between 2009 and 2021. The environment due to firefighting efforts is one-third the size of Southern California.
Both the federal government and the flame retardant manufacturer, Perimeter Solutions, dispute the analysis, saying the researchers evaluated different versions of the flame retardant. Perimeter spokesman Dan Green said the flame retardants used in aviation firefighting have passed “extensive testing to ensure they meet rigorous standards for aquatic life and mammal safety.” He said there was.
Still, the findings help explain why concentrations of heavy metals tend to increase hundreds of times in rivers and streams after wildfires. And while fire retardants are under increased scrutiny, the Forest Service has established buffer zones around lakes and rivers, but the agency's own data shows that flame retardants are still being inadvertently introduced into these bodies of water. Shown to be adrift.
In 2022, the environmental nonprofit Forest Service Employees for Environmental Ethics sued the government in federal court in Montana, demanding that the Forest Service obtain a permit under the Clean Water Act to cover accidental spraying into waterways. Ta.
The judge ruled that the agency must actually obtain a permit. However, the use of flame retardants was authorized to continue to protect life and property.
