How dangerous is the bonded asbestos found in mulch across Sydney?

Julia Collins from Australia’s Asbestos and Silica Safety and Eradication Agency told the ABC that bonded asbestos was only risky if it was “damaged, disturbed or deteriorating”.

“So, when asbestos is actually bonded in another material and the fibres are not released into the air, there won’t be a risk associated with it,” Ms Collins said.

"But if it’s broken up and it’s drilled into, when there’s any damage done, when it’s weathered and deteriorating, those fibres will then have a much higher risk of being released into the air.

“When asbestos fibres are inhaled, that’s where the danger lies.”

Ms Collins said the risk could not be fully understood though, until the extent of the contamination was known.