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  • Writer's pictureThe Beagle

Use Of Retardant And Foams During Firefighting Operations

Community Information from NSW Rural Fire Service The NSW RFS drops fire suppressant retardants from aircraft during firefighting operations to help slow the spread of a fire. Foams can also be applied by firefighters in controlling and containing a fire, and this helps to protect properties. This fact sheet contains information about what to do if these suppressants have been used on your property. Things to remember › It is coloured so firefighters can easily track where it has landed. › If fire suppressants come into contact with skin wash thoroughly with a gentle soap. › If eye contact is made, rinse the area with fresh water for 15-minutes; then consult a doctor. › If swallowed, rinse your mouth out with fresh water; then consult a doctor. › For your comfort, when cleaning surfaces be sure to wear protective equipment including safety glasses, disposable gloves and disposable face mask such as a P2 mask and wash your hands regularly. › Fire suppressants that have landed on the ground will degrade with exposure to the sun. What are fire suppressants? Fire suppressants are chemicals that slow the spread or intensity of a fire. They help firefighters on the ground and are sometimes also dropped from aircraft. Short-term fire suppressants are detergent chemicals mixed into foam, then applied using water. Long-term fire suppressants such as fire retardant are chemicals that are mixed with water to form a slurry. What are they made of? Long-term fire suppressants such as retardants are essentially fertilisers (ammonium and diammonium sulphate and ammonium phosphate), with thickeners (guar gum) and corrosion inhibitors (for aircraft safety). Sometimes a red coloured pigment, made from iron oxide, is added so that those spraying can see where they have released the fire retardant. Short-term fire suppressant foams are made of a combination of wetting agents and foaming chemicals, mixed with water. This allows the water to penetrate surfaces more easily. Their usefulness is limited against high-intensity fires, where long-term retardants have proven more successful. How do fire retardants work? Long-term fire retardants are mixed with water before they are dispersed over the target area. When the water is completely evaporated, the remaining chemical residue retards vegetation or other materials from igniting, until it is removed by rain or erosion. Fire retardants also work by binding to the plant material (cellulose) and preventing combustion. Gels and foams are used to fight fires by preventing the water they are mixed with from evaporating easily. They coat the fuel (grass, trees and shrubs) and prevent or slow down combustion. A slurry of gel can be pumped over the fire and it immediately cools down the intense heat and puts out the fire. What about environmental effects? Current evidence does not suggest any significant effects on birds or mammals. However, in Australia, long-term fire retardants have been observed to cause effects on some species of native plants (leading to low level damage to new growth). Water plants and animals are more sensitive to the effects of fire retardants; foams in particular can be moderately toxic to aquatic life. For this reason, pilots try not to apply fire suppressant retardants within 100m of waterways, but these agents can drift across buildings. What about health effects? Irritancy testing on animals shows these chemicals have little effect. The concentrated powder may cause minor respiratory irritation, to workers who are handling it. Once it is mixed into slurry this health effect does not occur. Workers require gloves and goggles and dust masks when handling the powder. Tips on cleaning up fire retardant residue If aerial fire suppressants (primarily retardant) or fire fighting foam residue is present on the house and/or cars, use a mild detergent and brushes to scrub and dilute the dried residue and flush it from the surfaces; rinse with clean water. Take care - it could be slippery. Gloves and non-slip shoes should be worn. For properties where downpipes are connected to water tanks, these should be disconnected to stop further retardant being washed into tanks. If the fire retardant does enter your water tank: Do not drink it. High levels of ammonia and sulphate in water will make it smell terrible and taste salty. It will not be suitable as drinking water for humans or animals (pets or livestock). The water can still be used for irrigation and fire fighting. For property owners who are unable to clean up any residue themselves or may require assistance for drinking water shortages you should contact the local Fire Control Centre on (02) 6739 6900.


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