A smoke alert has been issued for Mandurah to Bunbury including Pinjarra and the Forrest Highway.
The smoke is due to prescribed burns being carried out by Parks and Wildlife Service together with multiple private property burns in the area.
Smoke is trapped under a low inversion and has combined with fog.
Motorists are reminded to drive to the conditions as smoke and fog may reduce visibility.
The vehicle check point on the Forrest Highway has temporarily been moved due to the conditions.
WHAT TO DO:
If the smoke is particularly thick, it is recommended people shut doors and windows and turn off air-conditioners.
Smoke may reduce visibility on some roads and motorists should take care, turn on headlights and travel at appropriate speeds when travelling in these areas.
People with asthma and pre-existing respiratory or cardiovascular illnesses should follow their pre-prepared treatment plan.
People with conditions exacerbated by smoke should take precautions in line with their medical advice for these circumstances.