Air monitoring can be carried out even when no removal works are taking place – this is called Background Monitoring. This involves testing the air for fibres prior to any work which may disturb known asbestos materials. This may be conducted to determine if other fibres may be present in the air.
Air monitoring carried out during an asbestos removal is called Exposure Monitoring. This involves determining a person’s risk to airborne asbestos exposure by taking regular samples within the working area while removing. Exposure Monitoring is used to reliably estimate a person’s exposure to asbestos so that it can be compared with the national exposure standard.
Air monitoring that is taken out after completion of removal works is referred to as Clearance Monitoring. Clearance Monitoring is performed once the area has been decontaminated and dried, and a clearance inspection must be undertaken by the occupational hygienist. Clearance monitoring uses static or positional samples to measure the level of airborne asbestos fibres in an area after the work on asbestos has been completed. An area is cleared when the level of airborne asbestos fibres is measured as below 0.01 fibres/ml.