Perth residents are being warned of another haze caused by smoke from what is believed to be a deliberately lit fire near Denmark.
The Department of Parks and Wildlife issued the smoke alert for the Perth metropolitan area and south of the metropolitan area this afternoon.
"The smoke is from a bushfire that started last Friday in Mt Roe National Park, approximately 28km north-west of Denmark," a department spokesperson said.
"It is residual smoke from the weekend that went out to sea and is being blown on shore under the influence of westerly winds."
The haze is expected to clear tomorrow.
People with health conditions exacerbated by smoke are urged to take precautions.
"People with asthma and pre-existing respiratory, cardiovascular illnesses or diabetes should follow their pre-prepared treatment plan," the Department of Parks and Wildlife said.
If the smoke is particularly thick, residents are urged to shut 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," the department said.