A smoke alert has been issued Mandurah through to Bunbury including Dwellingup, Waroona and Harvey.
Parks and Wildlife Service at the Department of Biodiversity, Conservation and Attractions issued the alert.
The smoke is the result of a prescribed burn being carried out in the 12 kilometres north-north-east of Dwellingup.
The smoke is expected to clear by Friday.
The following information has been issued by the department.
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.
KEEP UP TO DATE:
The next update will be issued when the situation changes