Five airport sites across the state, including Perth Airport, are known or suspected to be contaminated with the chemicals, according to Airservices Australia, an Australian government-owned corporation which is responsible for aviation firefighting.

Airservices Australia is assessing Perth and Broome airports, as well as the former airport sites at Karratha and Port Hedland.

Jandakot Airport is now privately run, but its managing director John Fraser said an investigation conducted four years ago found small areas of contamination by perfluorinated chemicals.

"It's not a dangerous situation and we are monitoring it," he said.

An Airservices Australia spokesperson said it would assess the level of contamination — and test ways to remediate the sites — over the next 12 to 18 months, but planned to publicly release some results in the coming months.

A firefighting foam called 3M Brightwater, which contained the dangerous Perfluorooctane sulfonate (PFOS) and Perfluorooctanoic acid (PFOA), was used at the five WA airports until 2003.

It was then replaced by Ansulite, which was later found to contain traces of the chemicals, until 2010.

Since then, a foam called Solberg RF6, which is free of the chemicals, has been used at civilian airports with firefighting services.

The WA Department of Fire and Emergency Services has also found one bore on a semi-industrial property neighbouring its Forrestfield training academy is contaminated with the chemicals.