A so-called Unified Command, consisting of representatives of local, state and federal authorities in the US, continues to monitor and fight a major chemical fire at TPC Group in Port Neches on the Texas Gulf coast.

The blaze that followed an explosion in the early hours of Nov. 27 has been contained but still not extinguished.

Reports that a third tower at the plant that was processing butadiene at the time of the incident had collapsed were erroneous,  the command group said, explaining that the noise heard in nearby areas resulted from the “settling” of impacted equipment.

Most of the 50,000 residents living within a four-mile radius of the affected facility were evacuated last week but are now being allowed to return, despite the lingering smoke and fumes.

Jefferson County officials said they will continue to monitor air quality as long as smoke emerges from the plant. However, at a news conference Judge Jeff Branick, the county’s highest official, warned returning residents that smoldering debris from the fires could contain asbestos.

When the plant was first built, asbestos was still commonly used, Branick explained. Plant management noted separately that some production equipment contained asbestos insulation, adding that emergency response crews of toxicology consulting firm CTEH will lead debris removal efforts.

The Unified Command said it “remains diligent” in its efforts to monitor air quality around the facility and in the community, but without mentioning asbestos asserted that stationary and roaming air monitoring results “continue to indicate no human health concerns.”

Insurance claims representatives began visiting area homeowners on Dec. 1, starting with the area of highest impact, near the plant, while removal crews and assessed debris.

To date, no further information has been released as to the cause of the explosion and fire that initially injured three people.

The business now known as TPC has had multiple owners since it began operations in 1942. The list includes Texaco, Goodrich and Huntsman.