Asbestos Inspection and Assessment of School Buildings
Planning the inspection
An inspector first reviews building records, then conducts a walk-through to identify homogeneous areas - areas of surfacing, TSI, or miscellaneous material that are uniform in color and texture and were applied at the same time. Sampling is then performed within each homogeneous area. Bulk samples are analyzed by PLM (polarized light microscopy); point counting may be used to quantify low-percentage samples.
The seven assessment categories
Each homogeneous area of friable ACBM is assessed as: damaged or significantly damaged TSI, surfacing, or miscellaneous; friable but not damaged; or nonfriable. The assessment drives whether a response action is recommended.
Traps
- Distinguish homogeneous area (sampling unit) from functional space (a room or group with similar function, used in management planning).
- A common trap: assuming a "positive" sample means the entire homogeneous area is ACM - actually, if any sample exceeds 1%, the whole homogeneous area is treated as ACM.
- Inspectors must consider inaccessible areas and note them; they are not required to destroy the building to gain access, but must document assumptions.
Worked example
A hallway has three samples: 0.5%, 1.2%, and 0.8% asbestos. Because at least one sample exceeds 1%, the homogeneous area is classified as ACM. The inspector records it as friable surfacing ACBM and assesses its condition.
Rule of thumb
Any sample >1% makes the homogeneous area ACM.