What is the pink powder sprayed over the California wildfires?
As the wildfires in Southern California continue to burn, streaks of bright pink fire retardant have become a familiar sight.
Fanned by strong Santa Ana winds, the fires have killed at least 25 people and burned around 40,000 acres in the greater Los Angeles area. More than a week after it ignited, the area’s largest blaze, the Palisades Fire, was 19% contained as of Wednesday. Los Angeles County has declared a public health emergency because of the smoke.
The powdered substance being sprayed over the wildfires is called Phos-Chek. It can be dropped from the air or applied via trucks on the ground. It’s primarily made up of water, ammonium phosphate — an ingredient commonly found in fertilizer — and pink coloring, though it’s thickened with gum to improve accuracy for aerial drops.
“Phos-Chek is a fertilizer-based retardant product. It’s the same ingredients that are used on your fertilizer for lawn care,” said Shannon Horn, chief operating officer at Perimeter Solutions, the maker of Phos-Chek.
When used in fire retardant, ammonium phosphate can change the way the cellulose in plants reacts to heat. Ordinarily, plants exposed to a fire’s heat begin to decompose and become fuel, but Phos-Chek acts as a coating, creating a barrier that consumes the heat energy. The reaction produces a nonflammable carbon material, thereby slowing a blaze to buy firefighters time.
Pink flame retardant is seen 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 be accurate in creating and identifying lines of retardant.
“Essentially, it lets pilots see where lines are dropped,” Horn said. “If it was clear, they wouldn’t know where the retardant lines are.”
Phos-Chek can fade over time in sunlight and be washed off with water, so it does not permanently stain a landscape.
Neptune Aviation, a Montana-based air tanker company, is among the services currently delivering fire retardant to areas affected by the fires. The company contracts with the U.S. Forest Service and California Department of Forestry and Fire Protection (Cal Fire).
Nic Lynn, Neptune Aviation’s vice president of operations, said three of the company’s air tankers are in use in Southern California. The planes use designated, government-established air tanker bases, he explained.
“We go to those pre-established tanker bases, where they mix the retardant and pump it into the airplanes. Kind of think of us like we’re a dump truck. We’ll carry the product from A to B,” he said.
Pink flame retardant is seen on a home in the hills of Mandeville Canyon in Los Angeles on Monday.
Neptune Aviation has conducted at least 93 missions and delivered more 280,000 gallons of retardant to combat the fires, Lynn added.
To protect ecosystems, the Forest Service and the Department of the Interior require planes to avoid dropping fire retardant within 300 feet of waterways (ground deliveries must also avoid waterways). Some exceptions can be made, however, including if “potential damage to natural resources outweighs possible loss of aquatic life,” according to the Forest Service.
The primary environmental concern associated with the retardant is the presence of heavy metals. A study last year suggested that one version of Phos-Chek had higher levels of metals like cadmium and chromium than is considered safe according to regulatory thresholds. Heavy metals are not directly added to the product but may come from naturally occurring impurities.
Horn, however, said that the version of Phos-Chek being dropped in California is “a different product from years ago.”
A sign at the entrance to a trail in Mandeville Canyon is covered in pink flame retardant in Los Angeles 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 fire retardants outweigh the risks.
“There’s very little evidence showing there are serious long-term health effects associated with it” for people, Zhu said.
She added that the immediate health risks posed by wildfire smoke, which contains high levels of particulate matter, are more severe than potential concerns linked to the fire retardant.
Exposure to smoke pollution can cause a range of respiratory and cardiovascular issues, such as difficulty breathing, bronchitis or heart attacks, according to the Environmental Protection Agency.
This article was originally published on NBCNews.com
