Firefighters are expected to be at the scene of a blaze at an industrial estate in Sheffield until Monday.
The fire broke out in a disused unit on Station Road, Ecclesfield, on Wednesday night and is still smouldering today.
Fire chiefs have stepped up their firefighting efforts, bringing in extra crews, but warned residents to expect more smoke in the area because of the extra activity to douse the flames.
They have also brought in specialist machinery to break up a huge mound of smouldering melted plastic.
A South Yorkshire Fire and Rescue spokesman said: “After bringing the machinery into use on site on Friday morning, firefighters have made better progress in tackling this blaze.
“However, the fire is deep-seated in the plastic materials and it should be expected that firefighting actions will continue throughout the weekend and possibly into Monday.”