The Perth Hills has been issued with a smoke alert from the Department of Parks and Wildlife.
The smoke is from prescribed burns carried out today to manage bushfire risk, nature conservation and for forest management.
If the smoke is particularly thick it has been recommend that residents shut their doors and windows and turn off air-conditioners.
Motorists have been cautioned to take care as smoke may reduce visibility on some roads and residents have been asked to turn on their headlights and travel at appropriate speeds when traveling in affected areas.
People with conditions exacerbated by smoke, including asthma and cardiovascular illnesses have been asked to follow their pre-prepared treatment plan.
The Perth metropolitan area from the CBD to Mandurah has also been issued with a smoke alert.
The smoke is expected to clear over night.
For more information visit www.dpaw.wa.gov.au