Residents were advised to keep their doors and windows closed after a large fire at an industrial estate.
Large plumes of black smoke could be seen billowing from Rainford Industrial Estate on Saturday evening.
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Merseyside Fire And Rescue Service said they were called to a "significant" blaze on Sandwash Close at 6.40pm.
Five fire crews and a support vehicle attended to tackle the blaze, which was in an industrial unit.
A spokesman said: "The incident has been divided into sectors and crews are wearing breathing apparatus while fighting the fire in each sector.
"Residents in the area are advised to keep doors and windows shut. Anyone with an existing medical condition should keep medicines nearby. If any ill effects are experienced contact NHS number 111."
Merseyside Police urged motorists to avoid the area while the emergency services were dealing with the fire.