What is the red colour substance dropped from aircraft during bush fires?

Slurry, a mixture of mostly water and fertilizer designed to protect trees and other flammable material from flames.

What the air tankers and helicopters are dumping is a fire retardant known as slurry, a red coloured mixture of mostly water and fertilizer designed to protect trees and other flammable material from flames. The coating clings to vegetation and insulates it from the approaching inferno; the fertilizer helps the damaged areas regrow in the wake of the blaze. The powdery concoction is a key ingredient of a multi-pronged firefighting strategy; after the air drop, bulldozers and ground crews move in to cut a fire break designed to halt the advancing flames.

Slurry is dyed bright red to aid in visibility and help tanker pilots drop a seamless line of retardant. "Basically, they're trying to box in the fire."

Another advantage of slurry is that unlike water, fertilizer doesn't evaporate. It offers still another bonus for farmers, who have requested that unused slurry be dropped onto their fields as aircraft make their way home.

Is Slurry Toxic?

The hundreds of thousands of litres of red slurry that air tankers are dropping on wildfires has a downside: It is toxic. As it is a mixture of fertilizer and water it contains the same ingredients as any other fertiliser, ammonia and nitrates, it has the potential to kill fish and taint water supplies. Pilots dispensing the slurry avoid dispatching near waterways, creeks, rivers or dams when possible. But if wildfires threaten people & property, RFS officials say, it’s drops away, and air tankers will drop chemicals as close as they need. All “misapplications” recorded and reported, allowing for effective monitoring and management if required post fire event. Air tanker pilots and crew commanders now are required to carry maps that identify sensitive terrain.

There are other chemicals associated with it, but ammonia and the nitrates are the ones we’re currently aware of that are the largest concern. These can change the water chemistry drastically. That can have a very quick and often lethal effect on fauna.

Massive fish kills have been documented after fires were put out in northwestern united states. National Parks and NSW Rural Fire acknowledges concerns about toxic fire retardants degrading habitat and watersheds.

Many wildfires burn in remote, rugged areas, and the application of fire retardant can slow the spread of a fire until ground forces can reach the area and begin construction of a fire breaks. In can be dispersed onto homes without damage, however it works better on the ground. It slows the advance of a fire so that ground crews can get in there.

Contact Survival Solutions for information on all fire safety procedures on 1300 040 362


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