A smoke alert has been issued for parts of Karnup and Baldivis.
Motorists travelling along Paganoni Road and the Kwinana Freeway south of Karnup Road may be impacted.
The smoke is due to a Parks and Wildlife prescribed burn about 5km east of Secret Harbour.
"Smoke may settle in low lying areas overnight and is expected to clear Saturday morning," a DFES spokesperson said.
"Motorists are asked to drive to the conditions."
Nearby residents are advised to shut doors and windows and turn off air-conditioners.
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