Clearances and Air Monitoring

Typical enclosure set up with a modular decontamination unit

M3 can complete Four Stage Clearances as well as different kinds of air testing.  The separate air testing types are Personal Monitoring, Reassurance air testing, Background air monitoring and Leak Testing. Only UKAS accredited companies can carry out asbestos air monitoring and four stage clearances.

Four Stage Clearances

Four stage clearances need to be completed after asbestos has been removed under fully controlled conditions by a licensed contractor.

Stage 1:  The analyst first confirms that the removal contractors have followed all their procedures and have the necessary documents. They also confirm the enclosure has been properly constructed and that transit and waste routes are clear.

Stage 2: The analyst checks inside the enclosure to confirm that all the asbestos that should have been removed is gone and that the area is clean.

Stage 3: Once the analyst has confirmed the area is visually clean they will run air tests inside the enclosure (the amount of air tests depends on the enclosure size). If the air test passes then the analysts gives the go ahead to bring the enclosure down. The previous checks are all to confirm that the area is safe and clean so no one is exposed when the enclosure is removed.

Stage 4: The analyst looks around the area to confirm that all waste has been removed, all of the enclosure has been taken down and that nothing has been left behind from the asbestos removal.

Personal Monitoring

Personal monitoring involves an individual wearing a small air pump to monitor their exposure to asbestos while completing a specific job. The most common reason to run them is on asbestos removal contractors as part of their exposure records.

A personal air pump


Reassurance air testing

Reassurance air testing is normally ran after an incident involving asbestos. For example if a leaky pipe causes a ceiling covered in asbestos textured coating to collapse. A reassurance air test would show whether the area was safe for occupation. They are also ran after non-licensed asbestos removals such as after the removal of asbestos cement or asbestos floor tiles.

These types of air tests are ideal if proof is required that an area is safe and can put residents or workers minds at ease.

Typical air pump set up for a reassurance or background air test


Background Air Testing

Background air testing is often performed before a job involving asbestos starts to get a baseline of fibres present in the air. This way an accurate picture of how many fibres were released during work can be made.

Background air tests can also be ran in places where asbestos items are in-situ but are not going to be removed. For example if there is an asbestos insulating board ceiling a client may request background testing to be performed once a month to confirm that there is no exposure risk.

Leak Testing

Leak testing is performed around the outside of an enclosure while asbestos removal works are ongoing inside. It is highly recommended that leak testing is performed whenever licensed asbestos removal work is undertaken.

The leak testing serves to confirm that the enclosure is doing it’s job and that no asbestos fibres are leaking out of unseen gaps. They would usually be ran near the air lock, bag lock and by the NPU.

Leak testing is essential when an enclosure is set up in an occupied building in order to ensure that the residents or workers are not being put at risk by the works been carried out.

About Air monitoring

Air monitoring measures the quantity of airborne fibres in any given environment. The methodology is roughly the same in each instance.  A pump is connected to a filter head by tubing. The pump maintains a steady flow, pulling air through a filter mounted in the filter head. After a given period of time a certain volume of air can said to have been sampled.  The filter is removed and examined for ‘respirable’ fibres under a microscope.  The number of fibres counted and the volume of air sampled lead to the calculation of a concentration of airborne fibre – most often expressed as fibres per millilitres of air (f/ml).