Asbestos air monitoring checks for the presence of respirable asbestos fibres in the air to assist with the assessment of exposure and the effectiveness of control measures. Respirable asbestos fibres are less than 3 μm wide and more than 5 μm long, and have a length to width ratio of more than 3:1.

Generally undertaken where asbestos containing products are in a poor condition, and potentially liberating asbestos fibres into the air, or where asbestos containing materials are being removed, asbestos air monitoring considers only respirable asbestos fibres to be a risk to human beings.

There is a presumption that all fibres observed under a phase contrast microscope that meet certain geometrical specifications are asbestos. Further testing of asbestos air monitoring may be required to confirm the chemical composition using transmission electron microscopy test equipment (TEM).

When should asbestos air monitoring be conducted?

The National Occupational Health and Safety Commission recommends that asbestos air monitoring should be performed whenever asbestos containing materials (ACM) are being removed. Airborne asbestos fibres are generated by the disintegration of asbestos containing materials. Asbestos air monitoring can also assist to provide a quantitative analysis of the risk.

Asbestos air monitoring is mandatory when the asbestos material is friable; friable asbestos is asbestos that can be crushed and turned into a powder or small particles.

Types of asbestos air monitoring 

The different types of asbestos air monitoring and testing include background asbestos air monitoring; asbestos exposure air monitoring; control air monitoring; and clearance air monitoring.

Background asbestos air monitoring involves testing the air for respirable fibres prior to work, which may disturb known asbestos materials. 

Asbestos exposure air monitoring tests the air in a person's breathing zone to determine their likely exposure to respirable asbestos fibres. Exposure monitoring and testing is designed to reliably estimate the person's exposure, so that it may be compared with the national exposure standard.

Control asbestos air monitoring involves testing the air to measure the level of respirable airborne asbestos fibres in an area during work on asbestos containing materials. Control monitoring is designed to test the effectiveness of control measures while work or removal is undertaken on asbestos containing materials.

Clearance asbestos air monitoring tests the air to measure the level of airborne asbestos fibres in an area following work or removal of asbestos containing materials. An area is ‘cleared' when the level of airborne asbestos fibres is measured as being below 0.01 fibres/mL.

Safe Environments Pty Ltd conducts asbestos air monitoring and testing services in accordance with the Guidance Note on the Membrane Filter Method for Estimating Airborne Asbestos Fibres 2nd Edition [NOHSC: 3003 (2005)]. Their laboratory analysts participate in the National Asbestos Program (NAP) run by a division of NATA (National Association of Testing Authorities), which seeks to test and monitor the competence of asbestos fibre counting analysts.
