As fire crews and air tankers work to block the wildfires' explosive growth, images of red clouds of fire retardant falling onto trees are common. What is it — and what's in it?

The bright substance blanketing areas of Los Angeles County has long been used to stop wildfires from spreading.

A firefighting aircraft drops Phos-Chek pink fire retardant on Pacific Palisades on Jan. 7 (Image credit: Mario Tama/Staff via Getty Images) It's hard to measure the efficiency of fire retardant ...

The vibrant red fire retardant is known as Phos-Chek and has been used by firefighters battling wildland blazes for over 50 years, according to its manufacturer, Perimeter Solutions. Between 2009 ...

Phos-Chek is made from ammonium phosphate ... The front steps and mailbox of an house in Mandeville Canyon after fire retardant was dropped on the neighborhood. AFP via Getty Images Use ...

Los Angeles firefighters are using Phos-Chek, a bright pink fire retardant, to combat wildfires threatening lives and property. Developed by Perimeter Solutions, Phos-Chek helps slow the spread of ...

Some of the visuals coming out of Los Angeles County over the past week show a vivid pink substance coating streets, cars and plants. This is fire retardant, dropped by aerial firefighting tankers in ...

There can't be anyone who hasn't seen horrific footage of the LA fires. Nor could anyone miss seeing plane after plane of some mysterious red liquid dumped on unburnt trees. What is it? Why is it red?

Phos-Chek, a bright pink powder, is being used to combat wildfires. Dropped from planes and helicopters, the fire retardant slows the flames and shields vulnerable areas. The retardant is ...

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 ...

When you buy through links on our articles, Future and its syndication partners may earn a commission. A plane drops pink flame retardant during the Eaton Fire in Los Angeles, California on Monday ...