This control measure should be read in conjunction with National Operational Guidance: Environmental Protection - Treatment

Neutralisation is a chemical method of making a spill less corrosive by applying a second material that will chemically react with the original to form a less harmful substance. The most common example is applying a base or alkali to an acid spill to form a neutral ‘salt’.

Firefighters should not assume that the salt produced by neutralisation is safe. These salts, while no longer presenting a corrosive hazard, can have other hazards (for example, they may be toxic or explosive).

The major advantage of neutralisation is the significant reduction of harmful vapours being given off. In some cases, the corrosive material can be rendered harmless and disposed of at much lower cost and effort. However, during the initial phases of combining an acid and a base, a tremendous amount of energy may be generated along with toxic and flammable vapours.

When a decision has been made to neutralise a spill, consideration should be given to the type of neutralising agent that will be used. Certain neutralising agents produce less heat when reacting and some materials are more environmentally friendly than others; the key concern is biodegradability. Environment agencies should be consulted prior to any neutralisation tactics being implemented.