Pink Flame Retardants: What We Know About Their Use in Combating California Wildfires

Firefighting aircraft in the Los Angeles area are not only dropping water: They are releasing hundreds of thousands of gallons of bright pink fire retardant as a crucial measure to combat raging flames, aiming to protect neighborhoods from destruction.

Since the fires ignited last Tuesday, they have claimed at least 24 lives, forced thousands to evacuate, and annihilated over 12,000 structures. Four major fires impacted by fierce Santa Ana winds have scorched approximately 62 square miles, as reported by Cal Fire.

Fire agencies assert that these suppressants—typically employed in forest fire combat—are vital. However, what exactly do they contain, and are they safe?

Here’s what to consider:

Why Are They Being Used in Los Angeles?

The fires are rapidly spreading across canyons and other challenging terrains that are hard for ground crews to access, according to Cal Fire.

While fire suppressants can be highly effective, they are not without limitations, the agency observed: Strong winds can render it perilous to fly at the low altitudes required for effective drops, and these winds can disperse the retardant before reaching the ground.

Apart from Cal Fire, numerous agencies, including the U.S. Forest Service, the fire departments of Los Angeles and Ventura County, local city officials, and the National Guard, have been involved in releasing fire retardant and water.

How Do They Work?

Aerial fire suppressants usually consist of a blend of water, ammonium phosphate (essentially fertilizer), and iron oxide, which is included to enhance visibility of the retardant, explained Daniel McCurry, a professor of civil and environmental engineering at the University of Southern California.

The Forest Service, which has deployed 13 aircraft to drop suppressants on the fires in Los Angeles, claims that these retardants suffocate a fire by cutting off its oxygen supply and reduce the burn rate by cooling and coating vegetation and other surfaces.

Perimeter, the supplier of fire retardant to the Forest Service and numerous other agencies, notes that the phosphate modifies the decomposition process of cellulose in plants, rendering them non-flammable.

Potential Effects on Environment and Wildlife

While fire suppressants are generally regarded as safe for human exposure, many are concerned about their possible effects on wildlife.

The Forest Service restricts the use of aerial suppressants over bodies of water and habitats of endangered species, “unless human life or public safety is at risk,” due to potential health concerns for fish and other wildlife.

McCurry, from USC, stated that he and other researchers found heavy metals, such as chromium and cadmium, in a commonly used suppressant by the U.S. Forest Service during their testing.

He suggested that the study indicates it’s “plausible” that fire suppressants could lead to increases of chromium and other heavy metals in waterways downstream from wildfires.

“We don’t quite have conclusive evidence yet because it’s challenging, albeit not impossible, to trace the origin of heavy metals,” McCurry said. “We are making strides to address this.”

Perimeter, the manufacturer of the fire retardant used by the Forest Service, highlighted that McCurry’s findings pertained to a formulation that is neither in use in California nor utilized by the Forest Service anymore. The company asserts that it does not include metals, which they suggest are naturally occurring in all ammonium phosphate fertilizers, and emphasizes that their aerial suppressants have been thoroughly tested by the USDA Forest Service, meeting or exceeding all health and safety standards.

Use of Retardants Seen as Imperative to Avoid Greater Risks

The deployment of fire retardants is crucial in extinguishing wildfires that pose health threats to millions, including exposure to a toxic blend of microscopic particles that can inflict respiratory and cardiovascular issues by penetrating deeply into the lungs and bloodstream.

Research indicates that wildfire smoke has contributed to as much as half of all harmful particulate matter air pollution in the western United States in recent years, a consequence of increasingly destructive wildfires.

Furthermore, recent findings released by the Alzheimer’s Association suggest that wildfire smoke may be more detrimental to brain health compared to other forms of air pollution, heightening the risk of dementia.

“Employing wildland fire retardant is the most effective strategy to save lives, safeguard communities, and contain fires,” remarked Edward Goldberg, vice chairman of solutions at Perimeter.

McCurry, the USC researcher, emphasized the need for more research on fire suppressants—especially in Los Angeles once the fires have subsided—but acknowledges their importance: “If I had a brush fire approaching my house, I’d prefer a substantial application of (fire retardant) in front of it.”