Four workers have been treated for smoke inhalation after 70 tonnes of waste paper caught fire at a recycling centre in Sydney's west.
The NSW Fire Brigades said the fire started at midday at the Visy Recycling Centre at Smithfield.
Ten fire brigade units are on the ground and expect to be there for many hours.
"The paper will be smouldering for a long time," a spokesman told AAP.
"It's an open fire, no property is affected."
"The workers were treated at the scene."