Firefighters say they will continue making safety checks at a recycling plant following a massive blaze over the weekend.
More than 60 officers were called to tackle the fire that started on Saturday evening at Capital Valley Plastics in Blaenavon, Torfaen.
Crews said about 600 tonnes of recycled plastic was involved in the fire.
The fire was finally extinguished after noon on Sunday.
South Wales Fire and Rescue said investigators had returned to inspect the site on the Kays and Kears Industrial Estate on Monday morning to ensure it was safe.
It followed a multi-agency response to the fire, including assistance from Natural Resources Wales, Public Health Wales and Gwent Police.
Neighbouring properties were asked to keep doors and windows closed due to smoke and fumes during the fire.
"A clean-up process is now underway and we would like to remind local residents that the recycling plant remains closed at this time," said a fire service official.
"Natural Resources Wales are continuing to work on a number of measures to help minimise the impact of pollution to the local environment.
"The site will remain closed as a precaution to allow for a full clean-up operation and to ensure that the area is made safe."