Rockingham, Mandurah and surrounding areas were blanketed by smoke overnight.
The smoke was due to prescribed burns being carried out by the Parks and Wildlife Service.
A smoke alert was issued for Busselton, Donnybrook, Bunbury, Mandurah and the Perth metropolitan area on Tuesday night.
The smoke is expected to clear this morning.
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.
Warnbro man charged with more child abuse, animal cruelty offences
Teen threatened, robbed by offenders on e-scooter in Mandurah
Labor candidate for Secret Harbour Georgia Tree vows to fight for locals
Safety Bay man arrested after Perth police pursuit comes to crashing end
Port Kennedy before and after school care provider fined $33k after 'distressed' boy left alone in room
Dog ball library created at Dawesville beach in memory of beloved pet
WATCH: Police investigate South Yunderup motorbike theft as sellers warned to stay vigilant
Woman, child taken to hospital after car crashes into guard rail in Greenfields
WA Police warns Telstra outage is impacting calls to triple-zero