The importance of keeping dust under control in our mines

Dust Management – The importance of keeping dust under control in our mines

A perspective from Dr Rob McCartney, Occupational Physician, Resile

For the past couple of years, the mainstream press has been filled with reports of a “Black Lung” resurgence. This has focussed more than ever the obligation on mining companies to ensure they are managing risk and monitoring the health of their workers and contractors.

Australasian Mine Safety Journal brings an occupational medical perspective to this issue provided by Dr Rob McCartney, an Occupational and Environmental Physician from Resile Health.

Dust and Health

We all need to breathe to stay alive. To keep mine workers healthy, managing exposure to dust and monitoring impact on worker health goes hand in hand.

The body has a number of ways to protect itself from dust. These include:

1. Your nose hair and mucus – most large dust particles are caught and stopped in the nose hair and mucus
2. Your cough – particles which go further are then caught in the mucus produced in the bronchi and bronchioles. Tiny hairs move this up to the throat to be coughed out.
3. Tiny air sacs (alveoli) deep in the lungs contain special cells called macrophages whose role is to swallow up the dust particles.

The body has some defences against dust – which work up to a point.

Types of dusts

We class dust in two broad categories – inorganic dust which includes rocks and soil containing metals or minerals (e.g. silica, asbestos and coal) and organic dusts which are those from plants or animals (e.g. grain dusts).

Predicting the way a group of workers will react to dust is not always straightforward. Factors to consider include the type of dust exposures, how much, how frequent as well as individual responses (See Fig 2.0).

We know different types of dust particles cause different pathophysiological responses:

Specific risk for coal mine workers

Coal Mine Workers are at risk of developing a range of occupational dust lung diseases from long-term exposure to high levels of respirable coal and silica. These include:

• Coal workers’ pneumoconiosis (CWP)
• Mixed dust pneumoconiosis
• Silicosis
• Chronic bronchitis
• Emphysema or chronic obstructive pulmonary disease (COPD)

Coal Workers Pneumoconiosis (CWP or Black Lung)

This is a pneumoconiosis due to chronic inhalation of coal dust. The lungs react to exposures, causing scarring of the lung tissue which reduces the elasticity of the lungs. If enough scarring occurs the lung function is severely impaired.

There are two types of CWP:

Simple CWP – individuals with early-stage CWP may show no symptoms, however, typical symptoms can include a cough, sputum production, wheezing, and shortness of breath.

Complicated CWP (Progressive Massive Fibrosis) – Areas of fibrotic or scar tissue in the lungs is observed to be greater than one centimetre in diameter.

PMF may be debilitating and can be a life-threatening condition, and individuals may present with more severe symptoms.

Mixed dust pneumoconiosis

To add to the complexity of this condition, other carbonaceous material also can induce this disease. It may represent a mixture of CWP and silicosis (mixed dust).

Silicosis

Silicosis is a progressive, disabling, and sometimes fatal lung disease.

Silicon dioxide is commonly found in nature as quartz which makes up about 10% of the earth’s crust. Respirable (<10?m) crystalline silica can cause lung damage.

Respirable silica exposure is particularly damaging to the lungs related to the size and structure of the particles.

• Small particles are more likely to reach deep in the lungs – the bronchioles and alveoli.
• The surface structure of silica causes a complex pathological reaction in the cells of the lungs which causes damage to cell membranes, inflammation and ultimately fibrosis (or scarring)

Exposure to crystalline silica can cause progressive, disabling, and occasionally fatal lung disease. We also know that cigarette smoking adds to the lung damage caused by silica.

Exposures to crystalline silica can result in: chronic bronchitis; emphysema, acute silicosis, silicosis (>10 years exposure), lung cancer, renal impairment and scleroderma.

Reducing dust diseases

Dust disease in mine workers can be reduced by:

• Reducing exposures to dust plus

• Regular medical (doctor) health surveillance

• Ceasing tobacco use – smoking reduces the lung’s ability to clear dust and increases the risk of cancer

We know that when human lungs are exposed to certain dusts they respond in ways to protect the body. We also know that too much dust causes sickness. The best response to prevention of dust diseases is a dual health and safety program where health and safety work together.

What does this look like? <<refer diagram 3.0>>

1. Start with workplace monitoring to know the risks you are dealing with. Seek advice from an appropriately qualified and experienced Occupational Hygienist to ensure you are working with accurate dust measurements

2. Apply a hierarchy of controls to mitigate risk

These steps then inform your health management plan:

3. Make sure individuals are fit and safe to do the work

4. Maintain worker health through education and health promotion (e.g. quit smoking programs)

5. Monitor worker health – health surveillance is best managed by an Occupational Physician to guide the selection of the right assessment at the right time.

1. This enables early identification of health risks and via the workplace, feeds back into mitigation strategies
2. Where a worker is unwell, efforts are directed into returning the worker to health, low risk and back to work