Understanding Asbestos Release and the Potential for Re-contamination

Asbestos-containing materials can release hazardous substances in various forms. In the past, high-pressure washing of asbestos cement cladding sometimes occurred without proper controls, leading to asbestos slurry contaminating drains and electrical boxes. This slurry, often now buried under years of sediment in drains, can be challenging to detect.

Degrading asbestos cement releases fibres that can be carried into gutters. Blocked gutters can then deposit these fibres onto building surfaces. Upon drying, loose asbestos fibres become visible in these areas, and flakes of asbestos cement and AIB are commonly found below.

Drilling into asbestos cement roofs for fixing purposes generates asbestos dust and small flakes. Large roofs can accumulate a significant amount of this fine, easily disturbed dust underneath.

Re-contamination of Clean Areas:

Those responsible for managing asbestos-containing materials must be vigilant about the re-contamination of previously cleaned areas. While asbestos registers may indicate removal, several factors can lead to its return. For instance, gutters and drains cleaned of moss contaminated by adjacent asbestos cement roofs will become re-contaminated if the roof continues to drain into them.

Asbestos can also migrate back through the movement of contaminated materials or via airborne fibers.

Furthermore, uncontrolled maintenance work elsewhere on the site can spread contamination through footwear and other means.

A recent project highlighted the deceptive nature and potential for widespread dispersal of asbestos contamination. Initially, falling material from a high factory ceiling was suspected by the client to be asbestos insulation, resembling sprayed coatings or loose fill. Surprisingly, the substance was identified as moss heavily contaminated with chrysotile fibers. This contamination originated from moss washed into the gutters by heavy rain, which subsequently dried and was carried into the factory in large amounts by strong winds. Ultimately, the failing roof was replaced. This real-world scenario demonstrates how a deteriorating asbestos product can spread contamination beyond its original location, infiltrating internal cavities and eventually impacting work areas.

Aged Asbestos Cement