It’s widely used because it can slow flames in ways that water can’t. But it also contains heavy metals and other harmful compounds.

Aircraft battling fires raging through the Los Angeles area are dropping hundreds of thousands of gallons of hot-pink fire suppressant in a desperate effort to stop the flames.

Parts of Southern California are covered with pink fire retardant as firefighters try to control deadly wildfires raging in Los Angeles. But what is Phos-Chek fire retardant and is it safe?

The powdered substance sprayed over the California wildfires is called Phos-Chek. It contains ammonium phosphate — an ingredient commonly found in fertilizer.

Perimeter Solutions, the company that makes the substance, explains its hot pink hue. As crews battle fires in Los Angeles, the hot pink fire retardant they’ve dropped to stall the flames’ advance has become one of the striking visuals to come out of the disaster.