Working with white asbestos (chrysotile) and AIB asbestos building materials was finally prohibited in the UK in the 1990s. From 2006, when the Control of Asbestos Regulations was introduced as a comprehensive health and safety legislation, it may be assumed that the setting of Control Limits is most directed towards implementation of asbestos awareness training for those at highest risk within the asbestos management industry.

Control Limits refers to the maximum number of asbestos fibres that an employee can be exposed to whilst working with asbestos without using specialised breathing apparatus. Different periods of exposure are calculated to ensure that neither short or long-term exposure becomes hazardous.

Reminders of the dangers of white asbestos still present in many premises, especially school buildings built prior to the late 1970s, early 1980s, regularly surface when asbestos compensation cases are brought to court by an asbestosis lawyer and a sufferer’s partner or surviving family member. Former employees, who are known to have received no guidance or protection against breathing in the airborne fibres, are diagnosed with asbestos-related disease at the point when the mesothelioma or asbestosis symptoms first appear, as late as 50 years after the period of exposure.

Today, asbestos management entails rigorous training to ensure that personnel will be fully aware of when they will be exposed and preventative action needed to avoid exposure. The company employers will also need to be licensed or accredited and will demonstrate that they regularly carry out air testing and keep precise records of exposure.

The legislation gives clear instruction that the same training procedures apply to any other workers likely to be exposed to asbestos containing materials (ACMs) in their workplace as a result of building and demolition. They should also know how to decontaminate themselves should exposure occur. If high-risk ACMs are known to be present in working areas then air tests should be carried out to ensure that any fibre release is within limits.

The prevention of employees being exposed to asbestos exceeding the Control Limits also applies to asbestos workers (such as surveyors and asbestos strippers) and all other working situations where employees are known to work in close proximity to asbestos containing materials (ACM) i.e. plumbers, electricians and roofers.

Asbestos exposure is measured by testing the air in the working area. Air is drawn through a filter in a specialised ‘air pump’ and then an asbestos analyst counts the number of fibres present. The analyst can thus calculate the concentration of asbestos fibres in the air.

A pump siphoning 20 mililitres (ml) of air over 10 minutes finding 200 fibres (f), the concentration is calculated as 10 fibres per mililitre in 10 minutes (total fibres/total mililitres expressed as 20f/ml).

Asbestos exposure Control Limits

Asbestos Type      4 hr          10 min       12 week

Chrysotile only   0.3 f/ml   0.9 f/ml    72 fibre hrs/ml2*

Any other           0.2 f/ml   0.6 f/ml    48 fibre hrs/ml2*

*Total exposures over 12 weeks