Preventing dust-related lung diseases

Introduction

Three cases of dust-related lung disease have been reported in Queensland this year. A Nominated Medial Advisor detected lung disease in two underground coal mine workers as part of the Coal Mine Workers' Health Scheme. A third case was identified in a retired underground coal mine worker.

The exposure of workers to dust in mines is a key issue of concern for the Mines Inspectorate and we will continue to work with mine operators to minimise worker exposure to unhealthy dust levels.

What causes dust-related lung disease?

Inhaling excessive amounts of fine particles and dust can cause lung disease or pneumoconiosis.

Lung disease in mine workers can be caused by exposure to rock dust, coal dust, silica dust, diesel particulate matter, welding fume and other finely powdered materials that become airborne during mining, maintenance or processing.

The type of lung disease often relates to the nature of dust a worker has been exposed to. For example, Coal Workers' Pneumoconiosis also known as Black Lung is caused by exposure to coal dust, Silicosis is caused by exposure to crystalline silica dust and Asbestosis is caused by exposure to asbestos fibres.

Lung disease occurs when the human body is unable to break-down or remove certain types of dust once it has entered the lower parts of the lungs. Dust lodged in the lungs can cause an inflammatory process, scarring in the lungs and reducing the body's ability to breathe in oxygen and breathe out carbon dioxide. The scarring, over time, can also cause heart disease due to the restriction of blood flow from the heart to the lungs.

As the onset of lung disease is a gradual process, early signs and symptoms may go unnoticed by workers. Health surveillance is important as it is often possible to detect lung disease in its early stages.

Furthermore, dust-related lung diseases don't usually occur with a just few exposures to dust. These diseases typically occur when a person has been exposed to:

• dust over the exposure limit for many years; or
• dust at very high concentrations (e.g. ten times greater than the exposure limit) on a number of occasions.

Prevention and protection

Section 135 of the Mining and Quarrying Safety and Health Regulation (2001) and section 89 of the Coal Mining Safety and Health Regulation (2001) require that workers' exposure does not exceed the exposure limit applying to specific dust hazards.

Assessing and managing risk associated with occupational exposures can be complex. The approach to assessing risk must be established by a competent person, such as an occupational hygienist. The risk management process may require the use of specific risk assessment techniques. For example, assessing risk from occupational exposures could include measuring workers' exposure by sampling the work environment and collecting personal dust levels). This is why participation by workers in personal dust monitoring is important.

Figure 1 shows the relationship between each of the legislated risk management processes and some of the technical and administrative activities that may be undertaken to achieve an effective outcome.

When selecting controls during the risk reduction stage, the hierarchy of controls should be applied to ensure that workers' exposure does not exceed the exposure limit; and that exposure is as low as reasonably achievable.

Every effort should be made to reduce airborne dust and other contaminants to levels that do not require the mandatory use of respiratory protection. Mine operators and site senior executives are reminded that respiratory protection is the lowest order control in the hierarchy of control and relies heavily on worker compliance and enforcement by supervision to be effective. Failure to wear suitably selected and correctly fitted respiratory protection when required can result in a worker being directly exposed to airborne dust.

Authorised by Russell Albury - Chief Inspector of Coal Mines

Contact: Jack Farry, Senior Inspector of Mines , +61 7 3199 8010

Issued by Queensland Department of Natural Resources and Mines