A huge pile of building rubble riddled with potentially deadly asbestos has been dumped outside a business in Sydney's west for a third time in a matter of weeks.
Twenty tonnes of the dangerous rubbish was discovered about 8am on Monday in the car park of an industrial complex in Dunlop Street in Strathfield South.
A truck offloaded the waste on Sunday night, hitting the same site for the third time in a fortnight, according to media reports.
NSW Fire and Rescue's Norman Buckley said about 30 nearby factory workers were not exposed to the potentially toxic particles and wet weather overnight helped containment efforts.
"If it becomes airborne it becomes a concern to the public but thankfully we had some rain," he said.
"We didn't have to do any decontamination. (The workers) were moved to a safe area very quickly."
NSW Fire and Rescue called in six trucks and hazardous material technicians who made the site safe by wetting the material, bonding it together with glue and covering it.
It's now up to the business owner to pay for the clean up, Mr Buckley said.
Police are investigating the truck which was caught on CCTV footage while the NSW Environmental Protection Authority has also been notified.