Firefighters have spent the night cleaning up a chemical spill on the Kwinana Freeway.
A section of the freeway southbound was closed overnight from Riverside Drive to Canning Highway after sulphuric acid leaked from a vehicle from about 4pm.
Motorists who drove through the area have been urged to wash down their vehicles, preferably on grass.
Motorcyclists have also been advised to hose down their clothing immediately before washing thoroughly.
The spill is now contained and under control and the freeway has reopened.