Merck Manual

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Coal Worker Pneumoconiosis

(Anthracosis; Black Lung Disease)


Carrie A. Redlich

, MD, MPH, Yale Occupational and Environmental Medicine Program Yale School of Medicine;

Efia S. James

, MD, MPH, Yale School of Medicine;

Brian Linde

, MD, MPH, Yale Occ and Env Medicine Program

Reviewed/Revised Nov 2023

Coal worker pneumoconiosis is a lung disease caused by deposits of coal mining dust in the lungs.

  • Symptoms include cough and shortness of breath which can progress over time.

  • Chest x-rays and computed tomography are used to make the diagnosis.

  • People may take medications to help their breathing.

  • Prevention by minimizing exposure to coal mining dust is important.

People with coal worker pneumoconiosis have either

  • Simple pneumonoconiosis

  • Complicated pneumonoconiosis, also known as progressive massive fibrosis

In simple coal worker pneumoconiosis, coal mining dust collects around the small airways (bronchioles) of the lungs. People with simple coal worker pneumoconiosis typically do not have breathing symptoms.

Complicated coal worker pneumoconiosis or progressive massive fibrosis, a more serious form of the disease, develops in some people with simple coal worker pneumoconiosis. Large scars (at least ½ inch [about 1.3 centimeters] in diameter) develop in the lungs as a reaction to coal mining dust. Progressive massive fibrosis may worsen even after exposure to coal mining dust stops. Recently, rapid development of progressive massive fibrosis has been found among young coal miners, especially in the eastern United States. Lung tissue and blood vessels in the lungs can be destroyed by the scarring.

Following the enactment of the Coal Mine Health and Safety Act in 1969, there was a decline in coal worker pneumoconiosis in the United States. However, since the late 1990s there has been a resurgence of coal worker pneumoconiosis, especially severe progressive disease. This resurgence is most likely due to greater silica exposure. Possible explanations for the increased silica exposure include disregard for health and safety regulations, greater silica content in the coal mining dust, less accessible coal seams that require cutting through more rock, and changes in work practices, such as the use of high-powered equipment that can produce more dust with finer particles.

Causes of Coal Worker Pneumoconiosis

Coal worker pneumoconiosis is an occupational lung disease Overview of Environmental and Occupational Lung Disease Environmental and occupational lung diseases result from inhalation of dusts, chemicals, gases, fumes, and other airborne exposures. The lungs are continually exposed to the external environment... read more that results from inhaling coal mining dust over a long time, often 10 years or more. Cumulative dust exposure is the most important risk factor in the development of coal worker pneumoconiosis.

The quantity of crystalline silica in coal mining dust is also an important risk factor for progressive disease. Miners working in underground mines, closer to the extraction point, and those involved in cutting or drilling are at greater risk of coal worker pneumoconiosis.

Symptoms of Coal Worker Pneumoconiosis

Symptoms commonly include shortness of breath, cough, and sputum production. The disease can progress even after exposure stops. Progressive massive fibrosis can progress to end-stage lung disease.


Coal mining dust can cause chronic obstructive pulmonary disease Chronic Obstructive Pulmonary Disease (COPD) Chronic obstructive pulmonary disease is persistent narrowing (blocking, or obstruction) of the airways occurring with emphysema, chronic obstructive bronchitis, or both disorders. Cigarette... read more Chronic Obstructive Pulmonary Disease (COPD) (COPD) independent of smoking. Obstructive lung disease occurs in coal miners even in the absence of coal worker pneumoconiosis. Chronic bronchitis with symptoms of cough and sputum production is also common. The decline in lung function increases with greater cumulative dust exposure.

Lung cancer Lung Cancer Lung cancer is the leading cause of cancer death in both men and women. About 85% of cases are related to cigarette smoking. One common symptom is a persistent cough or a change in the character... read more Lung Cancer risk is elevated in workers exposed to coal mining dust. The mining environment contains multiple contributors to lung cancer risk, including silica and diesel exhaust fumes. The risk of tuberculosis is also increased in people with coal worker pneumoconiosis.

Diagnosis of Coal Worker Pneumoconiosis

  • History of coal mining exposure

  • Chest imaging (computed tomography or x-ray)

Doctors make the diagnosis of coal worker pneumoconiosis after noting characteristic spots on a chest x-ray or computed tomography (CT) scan of a person who has been exposed to coal mining dust for many years.

Treatment of Coal Worker Pneumoconiosis

  • Reduction of further exposure

  • Treatment of symptoms

Workers with more advanced coal worker pneumoconiosis, such as progressive massive fibrosis, should avoid further exposure.

Treatment of coal worker pneumoconiosis is directed toward the symptoms. People who have no symptoms do not need treatment. However, workers who have signs of obstructive lung disease (for example, difficulty breathing) may benefit from treatments used for chronic obstructive pulmonary disease Chronic Obstructive Pulmonary Disease (COPD) Chronic obstructive pulmonary disease is persistent narrowing (blocking, or obstruction) of the airways occurring with emphysema, chronic obstructive bronchitis, or both disorders. Cigarette... read more Chronic Obstructive Pulmonary Disease (COPD) (COPD).

Prevention of Coal Worker Pneumoconiosis

Preventive measures begin with eliminating or reducing exposure, such as suppressing coal dust at a work site and using ventilation systems. A properly fitted respirator that filters the air may provide some additional benefit.

Doctors usually recommend that coal workers have screening chest x-rays, so that the disease can be detected at a relatively early stage. If the disease is detected, further exposure to coal mining dust should be minimized to limit progression of disease.

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