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Pink Fire Retardant, a Dramatic Wildfire Weapon, Poses Its Own Dangers

From above the raging flames, these planes can unleash immense tankfuls of bright pink fire retardant in just 20 seconds. They have long been considered vital in the battle against wildfires. But emerging research has shown that the millions of gallons of retardant sprayed on the landscape to tame wildfires each year come with a toxic burden, because they contain heavy metals and other chemicals that are harmful to human health and the environment. The toxicity presents a stark dilemma. These tankers and their cargo are a powerful tool for taming deadly blazes. Yet as wildfires intensify and become more frequent in an era of climate change, firefighters are using them more often, and in the…

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  Debate Over Wildfire Retardants Continues in CA

Phos-Chek, that neon-pink goo that airplanes dump over wildfires, is a sticky slurry of ammonium phosphate designed to coat vegetation and other fuels to deprive advancing flames of oxygen. Fire authorities swear by the product, calling it indispensable. But critics argue that officials are overlooking the product's ecological risks. Studies have shown the retardant can harm plants, fish and other species, including steelhead trout and Chinook salmon. It can also act as a fertilizer that grows more vegetation, which can later act as fuel for fires.

 We’re dumping loads of retardant chemicals to fight wildfires. What does it mean for wildlife?

As western wildfires become bigger and more intense, state and federal fire agencies are using more and more aerial fire retardant, prompting concerns over fish kills, aquatic life, and water quality.

 Wildfire retardant is often ineffective. Here’s what communities should do instead

Right now air tankers are flying the skies above the western United States where wildfires threaten homes. When these massive firefighting airplanes drop gallons and gallons of retardant, it can seem like the cavalry has arrived. The problem is, retardant — like many other top-down or last-ditch government efforts — is often wildly ineffective.

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A pink powder is being used to fight California fires. It's getting everywhere

The retardant is typically sprayed around a wildfire on vegetation and land that is fire-prone to stop the flames from spreading to that area. According to the US Forest Service, retardants "slow the rate of spread by cooling and coating fuels, depleting the fire of oxygen, and slowing the rate of fuel combustion as the retardant's inorganic salts change how fuels burn."

Aerial fire retardants: It’s raining red

So what exactly is that bright red slurry dropped by planes during wildfires? Several different types of fire retardant may be used in fighting wild fires, including: Long-Term Retardants: these water-based mixtures often contain ammonium phosphate salts and other additives, and they are typically dropped on wood fuel in advance of a fire. The salts promote charring of wood materials, so the mixture continues to provide fire retardancy after the water has evaporated. The distinctive bright red coloring is an added dye that makes it easier for responders to keep track of treated areas.

After Wildfires, What Happens to Crops Soaked in Fire Retardant?

Hulbert said he spent 39 years ordering retardant drops without knowing much about the potential long-term implications. “This is 50-year-old technology,” he said. “I’m not sure it’s a good thing.”

Are fire retardants used to clean up wildfires doing more harm than good?

Long term retardants, mixed for delivery to wildfires, contain about 85% water, 10% fertilizer (all currently approved retardants use ammonium phosphate fertilizers), and 5% minor ingredients (colorant, corrosion inhibitors, thickener [natural gum and clay], stabilizers, and bactericides). Colorants are added to make fire retardant visible, so that pilots can see where earlier drops were made and accurately aim subsequent drops to help connect or reinforce retardant lines.

Fire Retardant Use Explodes as Worries About Water, Wildlife Risk Grow

State and federal use of fire-retardant chemicals has grown significantly in recent years. Yet recent studies have shown the toxins are deadly to fish and may contribute to permanent changes in plant communities.

Fire retardant: What is it? Everything you need to know

Fire retardants can also cool the fuel through physical actions or endothermic chemical reactions. They come in various forms, including powder for mixing with water, fire-fighting foams, fire-retardant gels, coatings, or sprays for application to objects. Fire retardants are utilized to impede or decelerate the progression of fire, either through physical obstruction or by inducing chemical reactions. Fire retardant is not limited to a single chemical composition but can be formulated from a combination of various properties.

Firefighting Chemicals Are Dangerous for the Environment. Can That Change?

In firefighting, different fuels call for different chemicals and techniques. Class A fuels, like wood or paper, can be put out using water, often made even more effective with additives. You’re probably familiar with Class A fire retardants from photos of air tankers dropping red clouds near wildfires; they slow oncoming flames by changing how they burn. To be clear, these are different from PFAS—although they have their own risks. Made of salts or chemicals used to make fertilizer, they have killed fish and caused algae blooms; their use is now restricted near water.

It’s raining red: Why chemical fire retardants are on the rise

Fire retardants contain many of the same ingredients found in common garden fertilizers. Although they are United States Department of Agriculture (USDA) and United States Forest Service (USFS) approved and considered safe for humans and the environment, studies have demonstrated adverse effects on salmon and trout. Salmon at the smolt stage are vulnerable to chemical fire retardant when it’s accidently dropped over their habitat, particularly in stagnant pools and river eddies where it is not quickly dispersed downstream. Ash, mud, and debris resulting from fires can also affect waterways, but the long-term risks of fire retardant in sensitive aquatic and terrestrial habitats likely outweigh the other adverse effects of a fire event. Although Phos-Chek is sold as an environmentally beneficial product because it acts as a fertilizer after the fire, it also encourages the spread of invasive plants, which often capitalize on nutrient-rich environments.

Painting LA pink!

It is made using a mix of chemicals that are used to extinguish or slow down the spread of the blaze, including ammonium polyphosphate - which does not evaporate easily and stays set on materials for longer than water.

The Consequences of Spraying Fire Retardants on Wildfires

However, I can tell you from my research that the safety and usage guidelines for the fire retardants were developed nearly forty years ago. And the research that informed those guidelines was based on the amounts of chemicals that they were spraying back then, not at these increased amounts we see now.

This Gel Could Prevent Wildfires

There are a number of fire retardants used on active forest fires, but they can easily be washed away by rain or blown away by wind, so they don’t last long enough to prevent new fires. The new gel-like material can be used as a carrier fluid for these traditional fire retardants, making them stick to vegetation throughout the wildfire season.

What Are They Dumping on Wildfires?

What the air tankers are dumping is a fire retardant known as slurry, a mixture of mostly water and fertilizer designed to protect trees and other flammable material from flames. The coating clings to vegeation and insulates it from the approaching inferno; the fertilizer helps the damaged areas regrow in the wake of the blaze. The powdery concoction is a key ingredient of a multi-pronged firefighting strategy; after the air drop, bulldozers and ground crews move in to cut a fire break designed to halt the advancing flames.

What do firefighting chemicals do to a forest?

There are a fair number of risk assessments out there examining the impact of fire retardants on ecosystems — however, not a lot of them offer clear answers.

What is the flame retardant that planes are dropping on the LA fires?

So, how does it stop fires from spreading? Under normal conditions, cellulose in plant matter decomposes as it's heated, producing flammable compounds. Phos-Chek's maker says the reaction between the retardant and cellulose consumes heat energy from the approaching fire and produces non-flammable carbon material. The goal is to slow or stop the fire's spread, especially if the area includes homes or other structures.

What's in the Pink Flame Retardant Planes Are Dropping on the LA Fires?

“It’s basically a mixture of water, fertilizer, and then the red color that you see is just rust,” McCurry says. In the wild, the color fades over time with exposure to sunlight. “You might see a gum or thickening agent just to change the viscosity, how sticky this stuff is,” McCurry says. Thickeners also keep the material from drifting off-target, he adds, “But the business end of it really is ammonium phosphate fertilizer.” For anyone who’s heard of fertilizer being used in explosives: That’s ammonium nitrate. Phos-Chek commonly contains two types of salt: diammonium phosphate ([NH4]2HPO4) and ammonium polyphosphate ((NH4PO3)n).

Where Does Fire Retardant Fall in a Forest? Ask a Satellite

Knowing where fire retardant lands once it’s dropped from a plane is hard to pin down. A new remote sensing approach offers clues.

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Phos-chek

PHOS-CHEK® and FIRE-TROL® brand long-term fire retardants, Class A foams, and water-enhancing gels are the world’s leading chemical solutions for managing wildland, industrial and municipal fires.