Miners' lung disease

Causes and risk factors

Coal dust can irritate the sensitive tissues of the lung and lead to the development of several diseases:

Pneumoconiosis

Most well known is a condition called pneumoconiosis, which is the name given to a group of lung diseases caused by the inhalation and retention of dust of various sorts. It's also called industrial dust disease. In miners coal dust is to blame and the condition is also known as black lung disease or anthrosilicosis. Tiny particles of coal dust, around two to five microns in diameter, lodge in the alveoli where eventually they trigger an immune response which leads to fibrosis or scarring of the lung tissue. How fast and far the disease progresses depends on the particular mix of different minerals in the dust. A similar condition affects people who work for years around graphite, or man-made carbon, and another form of pneumoconiosis is asbestosis, caused by inhaling asbestos dust.

The risk of developing the disease is related to the duration and extent of exposure to the coal dust. It's much less common than it used to be, thanks to better control of exposure to coal dust but more than 200 new cases are still diagnosed in the UK each year. Most affected workers are over the age of 50.

Smoking doesn't make a person more likely to develop pneumoconiosis but, because it also damages lung function, it may make the symptoms of the disease worse.

Miners are also at increased risk of other types of lung disease that affect many other people in the population such as emphysema and chronic bronchitis.

Emphysema

Emphysema is one of a range of lung conditions known as chronic obstructive pulmonary disease (COPD). In emphysema there is over-inflation of the tiny air sac structures in the lungs known as alveoli. This over-inflation results from a breakdown of the walls of the alveoli, with loss of the elasticity of the lung tissue and a reduction in the ability of the lungs to function properly. As the lungs become less able to transfer less oxygen to the bloodstream, shortness of breath develops.

Miners are not the only group at risk of developing emphysema; the most common cause is smoking. COPD results in permanent lung damage in a significant number of smokers.

Emphysema can also be inherited. In these cases, sufferers are born with a deficiency of a protein crucial to proper lung function.

Chronic bronchitis

The other main condition which comes under the umbrella term COPD is chronic bronchitis. Cigarette smoke and coal dust both irritate the delicate lining of the airways, causing inflammation and increased mucus production which narrow the breathing tubes, making it harder to breathe. Chronic bronchitis or inflammation of the bronchial system results. Gradually scarring or fibrosis develops, and the airways become irreversibly narrowed. Paralysis of the hair-like cilia which line the airways means that the lungs cannot clean themselves so effectively, increasing the risk of infection.

Symptoms

The commonest symptoms of all these respiratory conditions are:

• Shortness of breath
• Chronic cough
• Increased sputum or phlegm production (especially in bronchitis)
• An increased risk of chest infections in COPD. This results in a sudden worsening of symptoms, called an exacerbation
• Other vague symptoms of COPD include weight loss, tiredness and ankle swelling

Pneumoconiosis symptoms

Pneumoconiosis comes in two forms:

Simple pneumoconiosis: this form is not usually disabling. Patients may have no symptoms and the diagnosis is discovered by chance when a chest x-ray is taken. However it can cause mild symptoms and does increase the risk of chronic bronchitis

Complicated pneumoconiosis (also known as progressive massive fibrosis, or PMF) This usually leads to disability because it can increase the risk of complications such as:

• Failure of the right side of the heart (cor pulmonale)
• Lung cancer
• Pulmonary tuberculosis
• Respiratory failure

Emphysema symptoms

People with emphysema typically experience great difficulty exhaling. Because they tend to breathe at an increased rate (hyperventilate) to make up for their damaged lungs, and tend to be flushed (because) they are sometimes called 'pink puffers'. About half of those who suffer from emphysema find that it restricts their ability to carry out their normal daily activities. Complications can lead to heart disease.

Chronic bronchitis symptoms

People with chronic bronchitis suffer from long-term mucus production and coughing which can come and go over time, with symptoms usually lasting longer each time as the lungs become increasingly damaged and scarred.

Simple chronic bronchitis is defined as over production of mucus, associated with coughing, for at least two years and the cough lasting for most days for three months. As the condition progresses due to further exposure to risk factors such as mining dust or smoking, the lungs eventually become obstructed due to damage, resulting in chronic obstructive bronchitis.

People with chronic bronchitis are sometimes know as 'blue bloaters' because they tend to be cyanosed (have low oxygen levels in the blood, which tinges the skin blue) and increased lung volume because obstruction of the airways prevents air from leaving the lungs easily.

Chronic bronchitis can progress to emphysema.

Treatment and prevention

Pneumoconiosis: the diagnosis may be confirmed using a chest X-ray and tests of lung function, combined with a history of exposure to industrial dust.

There is no cure and no specific treatment for this disorder other than medicines that may help control symptoms and good management of complications. Avoidance of further exposure to coal dust is important to prevent further damage.

The main way to prevent the disease is to minimise the amount of coal dust breathed in by mine workers. This can be done by using protective masks, and by strictly controlling maximum permitted dust levels in occupational settings.

Those people who develop respiratory illness due to industrial dust exposure may be able to claim compensation – your employer should be able to tell you more.

Emphysema: Once damage is done it cannot be reversed but steps can often be taken to prevent further damage and treatment given to help sufferers live more comfortably with the disease. Bronchodilator drugs can be used to relax and open air passages in the lungs. Exercise may help to strengthen the muscles used in the breathing process.

Those with emphysema should also maintain overall good health habits, such as good diet, healthy weight, regular exercise and adequate sleep to build up resistance to infections which may exacerbate the symptoms of emphysema. In some extreme cases, the most severely diseased portions of the lung can be removed by surgery to allow the remaining lung and breathing muscles to work better.

Smokers should do everything they can to stop.

Chronic bronchitis: Chronic bronchitis is treated with bronchodilator drugs delivered through an inhaler. The role of steroid drugs has been controversial but these may help to reduce inflammation especially when there is an acute exacerbation or worsening of the condition (usually because of infection). Treatment with oxygen may also be helpful in more advanced cases. Exercise programmes are also helpful, to improve general fitness and lung capacity.

Antibiotics may be prescribed to treat bacterial infections during an acute episode, and sometimes as a preventative measure.

Not smoking and avoiding air pollution are the best ways to prevent chronic bronchitis.