by As wildfires continue to burn in Southern California, stripes of bright pink fire retardant have become a familiar sight.
The fires, fueled by strong Santa Ana winds, have killed at least 27 people and burned more than 40,000 acres in the Los Angeles area. More than a week after it ignited, the region’s largest blaze, the Palisades Fire, was 22% contained as of Thursday morning.
The powdered substance sprayed over forest fires is called Phos-Chek. It can be dropped from the air or deployed on the ground using trucks. It consists primarily of water, ammonium phosphate – an ingredient commonly found in fertilizers – and pink dye, although it is thickened with rubber to improve accuracy in airdrops.
Follow us for live coverage
“Phos-Chek is a fertilizer-based retarder product. They are the same ingredients used in your lawn care fertilizer,” said Shannon Horn, chief operating officer at Perimeter Solutions, the manufacturer of Phos-Chek.
When used as a fire retardant, ammonium phosphate can change the way cellulose in plants responds to heat. Normally, plants exposed to the heat of a fire decompose and become fuel. However, Phos-Chek acts as a coating and creates a barrier that dissipates the heat energy. The reaction creates a non-combustible carbon material, slowing a fire to buy time for firefighters.
Pink flame retardants on a car in the Mandeville Canyon neighborhood of Los Angeles on Saturday.
The primary purpose of the pink dye is simply to help firefighters and pilots accurately create and identify deceleration lines.
“Essentially, it allows pilots to see where lines are being dropped,” Horn said. “If it was clear, they wouldn’t know where the brake lines were.”
Phos-Chek can fade over time in sunlight and can be washed off with water so it does not leave permanent stains on the landscape.
Neptune Aviation, an air tanker company based in Montana, is among the services currently delivering fire retardant to areas affected by the fires. The company contracts with the US Forest Service and the California Department of Forestry and Fire Protection (Cal Fire).
Nic Lynn, vice president of operations for Neptune Aviation, said three of the company’s air tankers are operating in Southern California. The planes use designated air tanker bases set up by the government, he said.
“We go to these pre-established tanker bases where they mix the retardant and pump it into the planes. Think of us as if we were a dump truck. “We transport the product from A to B,” he said.
Pink flame retardants on a home in the hills of Mandeville Canyon on Monday.
“Neptune Aviation conducted at least 93 missions and delivered an additional 280,000 gallons of fire retardant to combat the fires,” Lynn added.
To protect ecosystems, the Forest Service and the Department of the Interior require aircraft to avoid dropping fire retardant within 300 feet of waterways (ground deliveries must also avoid waterways). However, some exceptions can be made, such as when “the potential damage to natural resources outweighs the potential loss of aquatic life,” according to the Forest Service.
The biggest environmental problem associated with the retardant is the presence of heavy metals. A study last year found that a version of Phos-Chek had higher levels of metals such as cadmium and chromium than are considered safe under legal limits. Heavy metals are not added directly to the product, but can come from naturally occurring contaminants.
However, Horn said the version of Phos-Chek discontinued in California is “a different product than years ago.”
Pink flame retardant covers a sign at the entrance to a trailhead in Mandeville Canyon on Monday.
Yifang Zhu, a professor of environmental health sciences at the University of California, Los Angeles Fielding School of Public Health, said the benefits of using flame retardants outweigh the risks.
“There is very little evidence that this is associated with serious long-term health effects for people,” Zhu said.
She added that the immediate health risks from wildfire smoke, which contains high levels of particulate matter, are more serious than potential concerns related to the fire retardant.
According to the Environmental Protection Agency, exposure to smoke can cause a range of respiratory and cardiovascular problems, such as difficulty breathing, bronchitis or heart attacks.
This article was originally published on NBCNews.com
