What is it the red fire retardant dropped by planes to fight LA fires?

Authorities in the Los Angeles area are using a red fire retardant called Phos-Chek to battle large wildfires, with over 440 million gallons used across federal, state, and private land in the past decade. The retardant is mainly composed of salts that alter the way fire burns, decreases intensity, and slows advance. Approved by the USDA, it is considered safe and effective, although precautions are taken to prevent environmental harm, such as maintaining a buffer zone near waterways and monitoring for any intrusions.

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