Environment Minister Matt Kean says firefighting foam containing per- and poly-fluoroalkyl substances (PFAS) will be banned for all training and demonstration purposes in NSW from next month.

"Firefighting foam is the key cause of PFAS contamination in the NSW environment with concentrations detected at airports, defence sites, emergency service facilities, training facilities, major hazard facilities, and their surrounding environments," Mr Kean said in a statement on Monday.

"This ban on PFAS firefighting foam will significantly reduce the impact on our environment but still enable our emergency agencies to fight catastrophic fires that can have devastating impacts on life and property."

The use of any PFAS firefighting foam for training and demonstration purposes will stop next month and the use of long-chain PFAS firefighting foam will be restricted from from September 2022.

The use and sale of PFAS firefighting foam in portable fire extinguishers will be restricted from September 2022.

"These changes will make the phase out mandatory across NSW, and is a key step to bring our state into line with Australia's National PFAS Position Statement."

Exemptions will be available if a business has valid cause to continue the use of certain PFAS foams, and some exceptions apply.

Australian Associated Press