Asbestos Air Monitoring – Frequently Asked Questions

Should the results obtained using control monitoring be related to exposure standards, which apply to occupational situations where the fibres are principally asbestos?

The personal (exposure) monitoring results can only be directly comparable to exposure standards

Do the fibre counts representing asbestos fibre counts?

The Membrane Filter Method (used for asbestos fibre monitoring) does not distinguish between the different types of fibres, including organic fibres and synthetic mineral fibres (SMF).

What is the reporting limit of the method?  

<0.01 fibres/mL

What causes a flow fault in the sampling pump? And how are these results reported?

  • Low battery
  • Filter loading
  • Malfunction in the pump
  • Kink in the sample tube

The results must be rejected. Depending on the time that the flow fault occurred, the results may still be useful in determining the asbestos air concentration.

Is there different occupational exposure standards for the different types of asbestos? And what are they?


  • Amosite                 0.1 fibres/mL
  • Chrysotile              0.1 fibres/mL
  • Crocidolite             0.1 fibres/mL

What is the minimum sample time required for sampling?

100 minutes at 4L/minute

What is the difference between Control, Clearance and Exposure Monitoring?

Control monitoring uses static samples to measure the level of airborne asbestos fibres in an area and is designed to assist in assessing the effectiveness of implemented control measures. This method is intended to be used for the control monitoring of airborne asbestos fibres in situations that include sampling in the following situations:

  • Outside asbestos removal and encapsulating areas.
  • At the clean end of asbestos decontamination units.
  • For clearance sampling after asbestos removal and encapsulating.
  • Inside buildings, structures or ships which contain asbestos.

Exposure monitoring means monitoring in a persons breathing zone to measure their likely exposure to a hazardous substance. Exposure monitoring is designed to reliably estimate exposure so that it can be compared with the occupational exposure standard or provide an estimate of a persons exposure.

Clearance monitoring is undertaken within the asbestos removal work area after removal and encapsulating and before the area is deemed “safe”.

Asbestos controls are to remain in place until the results of the clearance asbestos air monitoring have been received.

What is a field blank?

Field Blank means a filter is treated in a similar manner as that of an analytical blank, except that it is associated with each batch of filters used for sampling in the field.