Foam used to fight fires at three regional airports has been found to contain a pollutant, and an order has been made to stop its use.

The Environmental Protection Agency confirmed on Monday that foam used by fire trucks at Palmerston North, Gisborne and Hawke's Bay airports contains PFOS (perfluorooctane sulfonic acid), which is harmful in the environment and may affect human health.

As a result, the EPA has served a compliance order on Task Protection Services Ltd, as part of its inquiry into fire-fighting foams. The company owns and controls fire trucks and fire-fighting foams at Palmerston North, Gisborne, and Hawke's Bay airports.

Lab tests are still being carried out, EPA chief executive Allan Freeth says, but the compliance order issued means Task Protection Services Ltd must stop immediately using the foam for training or testing purposes, and entirely by May 4.

"In the interim, it may continue using the foam for emergencies, in the interests of safety," he said.

Mr Freeth said the company must submit a plan to the EPA by April 10, detailing steps that will be taken to ensure the foam is no longer used. The plan must also show how the foam will be safely stored and disposed of.

The EPA announced its investigation into PFOS- and PFOA-containing fire-fighting foams in December. The inquiry is on-going, and the EPA is visiting airports across the country.

A similar compliance order was issued at Nelson Airport on February 27.

PFOS has been used in firefighting foams since the 1960s, but was prohibited in New Zealand in 2006.