What Is Phos-Chek? Pink Powder Being Used To Combat Los Angeles Wildfires
Phos-Check is a brand of long-term fire retardant that has been used to fight fires since the 1960s. It is said to contain roughly 85% water, 10% fertiliser and 5% minor ingredients.
Los Angeles is witnessing fast-moving and destructive wildfires, which have led to the death of at least 24 people, and destroyed more than 12,000 structures, scorching an area of more than 60 square miles. The fire burning in and around Los Angeles have claimed the homes of numerous Hollywood celebrities, including Billy Crystal, Jeff Bridges, and R&B star Jhene Aiko, according to reports.
Amid the wildfires, which have been raging for around a week, visuals have emerged on social media of air-tankers showering red and pink powders over neighbourhoods.
The pink substance, which is being dropped over the wildfires, is known as Phos-Check.
What is Phos-Check?
Phos-Check is a brand of long-term fire retardant that has been used to fight fires since the 1960s in the US. It is most widely used by the California Department of Forestry and Fire Protection, and is the world’s most-utilised fire retardant.
This fire retardant substance is marketed by a company named Perimeter and said to contain roughly 85 per cent water, 10 per cent fertiliser and 5 per cent minor ingredients, according to the USDA. Other components of fire retardant mixed in the substance include phosphate and sulfate salts mixed with clay to thicken the product.
Thousands of gallons of fire retardant powder is showered over wildfires through aeroplanes to stop the blaze.
The method of containing the Inferno has been widely being shared on social media, where clouds of red and pink powder could be seen in the fire-fighting effort in California.
ABD, Los Angeles'taki yangınlar sırasında uçaklardan püskürtülen pembe toz, Phos-Chek olarak biliniyor.
— GazeteVar (@gazetevar) January 13, 2025
Bu malzeme, özellikle orman yangınlarında alevlerin yayılmasını önlemek amacıyla kullanılıyor. pic.twitter.com/OLAo9I0nhS
Why Is It Pink?
The vibrant pink hue of PHOS-CHECK serves a critical purpose: it helps firefighters easily identify where it has been deployed and where it hasn't. According to a 2023 NBC Los Angeles report, this visibility allows ground crews to strategically build fire lines around the treated areas, potentially protecting lives and property.
"We tested every color in the rainbow, and the pink was by far the most visible. And, it's pretty," Melissa Kim, vice president of research and development at Perimeter Solutions, was quoted as saying in the report.
Kim further emphasised the importance of visibility: "If you can't see it, then it's essentially not effective. The purpose is they're flying in high smoke, low visibility with winds. The pilots have to get it right the first time. This job doesn't offer many second chances."
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How Does Phos-Check Work?
The retardant works by cooling and coating fuels, depleting oxygen from the fire, and changing the nature of how materials burn through the action of its inorganic salts, according to the US Forest Service.
Phos-Check owes its pink colour to colorants that are mixed into the fire retardant to make it visible. However, exposure to sunlight darkens it down to an earthy colour allowing pilots and ground crews to target the drop line.
In 2022, a group of employees of the United States Forest Service-filed a complaint claiming that aerially deployed fire retardant violates clean water laws.
According to this group, the chemical contaminates waterways, harms fish, and is ineffective at times.
However, Fire Retardants such as Phos-Chek remain indispensable in the management of wildfires. These chemicals create a barrier that slows the flames, giving firefighters valuable time to protect lives, homes, and ecosystems.