The August 2, 2026 fire at Portland’s historic Centennial Mills warehouse sent smoke, ash, and building debris into parts of Northwest Portland and the Pearl District. It took two hours for the flames to be extinguished, the fire left the eight-story structure unstable, and the event raised questions about asbestos and other contaminants that may have traveled beyond the property.
The City of Portland reports that debris samples have tested positive for asbestos. The warehouse was constructed in 1910 and contained asbestos-containing materials, although extensive abatement had been completed before the fire. Preliminary air monitoring outside the immediate fire area has indicated a low health risk to the surrounding community, but additional sampling and analysis have continued.
Demolition of the unstable structure presents another period when dust and debris will need to be carefully controlled.
Quick Summary
- The Centennial Mills fire released smoke, ash, and debris into areas of Northwest Portland.
- Some debris samples have tested positive for asbestos, although preliminary monitoring indicates a low airborne health risk outside the immediate fire area.
- Nearby businesses and property owners should check outdoor surfaces, HVAC intakes, filters, and occupied areas for visible debris, soot, unusual dust, or persistent odors.
- Suspect debris should not be swept, vacuumed, pressure-washed, or disturbed with a leaf blower.
- Testing may be appropriate when visible material is present, contaminants may have entered a building, occupants report concerns, or professional documentation is needed before cleanup or reoccupancy.
What Nearby Businesses and Property Owners Should Watch For
Smoke from a structure fire is different from smoke produced primarily by burning vegetation. A building fire can release a complex mixture of fine particles, ash, soot, fibers, metals, and chemicals produced by burning construction materials, equipment, stored products, and building contents.
Nearby property owners and managers should look for:
- Pieces of ash or paper-like debris on roofs, balconies, sidewalks, vehicles, and outdoor equipment
- Dark residue, soot, or unusual dust near doors and windows
- Debris around outdoor-air intakes or rooftop HVAC equipment
- Persistent smoke or chemical odors indoors
- Visible particles around supply vents or on interior surfaces
- Employee or occupant reports of eye, throat, or respiratory irritation
The presence of an odor does not necessarily establish a health hazard, and the absence of an odor does not prove that a building was unaffected. Conditions should be considered in relation to the building’s location, wind direction, ventilation system, and observed deposition.
Avoid Disturbing Suspect Debris
Because debris from the Centennial Mills fire has tested positive for asbestos, people should avoid dry sweeping, using leaf blowers, or vacuuming suspect material with ordinary household or shop vacuums. These activities can make settled particles and fibers airborne again.
The City recommends lightly misting small amounts of debris, wearing gloves and a mask, double-bagging the material, and washing afterward. Businesses, multifamily properties, and facilities with significant debris or uncertain conditions should obtain professional guidance before beginning cleanup.
Workers assigned to cleanup may also be subject to occupational safety requirements. Property managers should not direct employees or maintenance personnel to handle suspect asbestos-containing debris without first determining the appropriate procedures, training, and protective measures.
When Testing May Be Appropriate
Not every nearby building will require the same evaluation. An initial inspection can help identify whether testing is warranted and which methods are appropriate.
Depending on site conditions, an assessment may include:
- Sampling suspect debris for asbestos
- Examining surfaces for fire-related ash, char, or soot
- Evaluating fine-particle levels in occupied areas
- Inspecting outdoor-air intakes, HVAC filters, coils, and accessible duct components
- Testing for metals or other contaminants when the burned materials and exposure pathway justify it
- Assessing persistent odors and possible chemical contamination
Air testing alone may not provide a complete answer. Air samples represent conditions during a particular sampling period, while settled contamination may remain on surfaces or inside ventilation equipment. A useful evaluation combines the fire history, visual observations, building conditions, occupant reports, and targeted sampling.
Planning Cleanup and Reoccupancy
Businesses should document visible debris, odors, affected areas, HVAC operating conditions, employee concerns, cleanup decisions, and laboratory findings. This information can help guide restoration work, address occupant questions, and support insurance discussions.
Cleanup should be based on the extent and type of impact. In some buildings, replacing filters and cleaning accessible surfaces may be sufficient. Others may require specialized asbestos procedures, professional cleaning, HVAC evaluation, or post-cleaning verification.
How FACS Can Help
If your property may have been affected by smoke, ash, or debris from the Centennial Mills fire, FACS can help determine the appropriate response. Our Portland team provides asbestos consulting, structure fire and smoke assessments, indoor environmental quality evaluations, HVAC inspections, and targeted sampling.
We help property owners, employers, and facility managers understand what may be present, whether testing is needed, and how to proceed with cleanup and re-occupancy.
Contact FACS online or call (888) 711-9998 for more information.
Frequently Asked Questions
Did the Centennial Mills fire release asbestos?
Yes. The warehouse contained some remaining asbestos-containing building materials, and debris samples collected after the fire tested positive for asbestos. However, preliminary air monitoring indicated a low risk to the surrounding community from airborne contaminants. Monitoring and laboratory analysis have continued.
Should nearby businesses have their buildings tested?
Not every nearby building needs testing. An inspection may be appropriate when visible ash or debris is present, smoke entered the building, HVAC equipment was operating during the fire, unusual residue or odors remain, or employees and occupants report irritation or other concerns. The inspection findings should determine whether sampling is warranted.
What can be tested after a structure fire?
Depending on the building and the materials involved, testing may evaluate suspect debris for asbestos, surfaces for ash or soot, indoor air for fine particles, and deposited material for metals or other contaminants. HVAC filters, outdoor-air intakes, coils, and accessible ductwork may also need inspection.
Is air testing enough to determine whether a building was affected?
Not always. Air sampling measures conditions during a limited period and may not identify settled contamination on surfaces or inside HVAC equipment. A more useful assessment combines visual inspection, building and ventilation conditions, occupant reports, fire history, and targeted sampling.
Can maintenance employees clean up the debris?
Businesses should use caution before assigning employees to clean suspect debris. Dry sweeping, ordinary vacuuming, leaf blowing, and pressure washing can make deposited particles airborne again. When debris could contain asbestos, employers may also need to address worker training, exposure controls, respiratory protection, and other occupational safety requirements. See City of Portland updates here.
What should someone do if ash or debris is found?
Follow current public health instructions. For small amounts, Portland officials recommend wearing gloves and a well-fitting mask, lightly wetting the material, picking it up without breaking it apart, double-bagging it, and washing afterward. Significant deposits or uncertain materials should be evaluated before cleanup begins.
When should a professional environmental assessment be considered?
Professional assistance may be warranted when:
- Debris is widespread or its composition is unknown
- Smoke, ash, or odors entered occupied areas
- HVAC equipment may have distributed contaminants
- Employees or occupants report persistent symptoms or concerns
- Specialized cleanup may be required
- The owner needs documentation for restoration, reoccupancy, or an insurance claim