DEPARTMENT of Parks and Wildlife has issued a smoke alert for areas including Mandurah, Pinjarra, Lake Clifton, Preston Beach, Waroona, Yarloop and Wagerup.
The smoke is from a prescribed burn being carried out today 20km south-east of Dwellingup.
The smoke will be visible this afternoon and overnight and is expected to clear by tomorrow afternoon.
If the smoke is particularly thick, it is recommended people shut doors and windows and turn off airconditioners.
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.