Swab Sampling for Asbestos Contamination

There has been on-line discussions regarding the validity of swab sampling for asbestos contamination. The general tenor of the discussion has focussed on whether this testing can be used for conducting visual clearances following asbestos removal.

In my opinion there is only limited value of this type of sampling and the only area it has any validity is where it is used to determine whether dust contains asbestos. Furthermore, this technique is only for areas/surfaces suspected of being contaminated from deteriorating or damaged asbestos containing materials.

Swab sampling for any other purpose may identify asbestos fibres, however, the number of fibres found, even if made airborne, would not constitute an increased health risk to occupants. 

Issues associated with swab sampling are:

• There is no definitive sampling technique and no statistical analysis of the results obtained.
• A 'clean' surface can return a positive result if only one fibre bundle is found which in turn starts the misinformed 'one fibre can kill' response.

Visual clearances following asbestos removal are to determine if there is any visible dust or debris remaining that may contain asbestos fibres. There is no requirement to run a microscope over the entire area. This view is also supported by WorkSafe's Removing Asbestos in the Workplace Compliance Code 2008 which specifically states that 'wipe samples' are not required to validate visual clearance inspections.

Post removal clearance air monitoring is an acceptable means by which the space to be reoccupied can be assessed. If the air monitoring cannot detect asbestos fibres above the limit of 0.01f/ml, even if several fibres are found during the counting, there is no logical reason why the space cannot be re-occupied.

HAZCON's consultants have significant experience in asbestos contamination matters and can scientifically as well as empathically address concerns regarding asbestos in the workplace.