The retardant used in Alaska is 88% water with ammonium phosphate, a common fertilizer, as the fire-retardant component. The other ingredients include gum thickeners to help it cling to vegetation; conditioners to aid in mixing and flow through delivery systems; and coloring agents made up of clay and iron oxide so pilots can see where retardant has been applied.
Retardant applied to vegetation works as a fuel break to help slow the fire’s advance. It is not used to extinguish the fire but to hinder its spread so firefighters on the ground can build firelines and perform point protection operations in a safer environment.
Retardant is not considered hazardous but can cause skin irritation due to the ammonium. It is easily washed off with soap and water. The salts in the ammonium phosphate can be corrosive if left on vehicles and structures. The red coloring can stain certain materials. Scrubbing surfaces or power washing with a mild soap or detergent can help in the cleaning process.
It will not harm animals but feeders and watering equipment for domesticated animals should be cleaned. Fish and other water creatures may be impacted by fire retardant, but that threat is low. Great care is exercised to minimize any introduction to rivers and lakes.
The main additive is basically a fertilizer that can provide plants nourishment. Retardant not removed from vegetation may cause it to brown and whither. After rain, plants should return to normal and be enhanced due to the plant nutrients.