Breathing in fine dust particles over an extended period of time. Mine workers’ are subject to the disease due to constant exposure levels of: 
rock dust 
coal dust 
silica dust 
diesel particulate matter 
welding fumes 
other particle airborne material
Type of exposure and disease: 
Pneumoconiosis is related to Coal Dust 
Silicosis is related to crystalline silica 
Asbestosis is related to Asbestos
Eventually the body is not able to remove harmful types of dust from the lungs.  Dust stuck in the lungs causes inflammation which leads to tissue scarring diminishing the lung capacity to bring in oxygen and expel carbon dioxide. 
The scarring of tissue of the lungs can lead to heart disease due to blood restriction. 
Early signs and symptoms may not manifest for years and may go unnoticed by workers’.  It is imperative that Workers’ Health is continually examined and it's the key in early detection.
Workers’ at greater risk may have been exposed to:
dust over the exposure limit for many years
dust at very high concentration (< 10 x exposure limit) on repeated 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.
The management of risk must be established by a competent person, such as an occupational hygienist. The risk process may include specific risk assessment techniques.
Suggestion: Sampling work environment to indicate actual dust exposure & implement controls required.
Controls applied to continually follow legislated limits and to further reduce exposure to as low as reasonably achievable. 
It is recommended that mine operators audit and review the effectiveness and implementation of the site safety and health management system to minimise the risk of lung disease to workers.
It is also recommended site senior executives review that a mine's current management plan for dust includes regular monitoring and assessment of the working environment, work procedures, and equipment and installations at the mine to minimise worker exposure to unhealthy dust levels.
Summary: Preventing dust-related lung disease Dept. of Natural Resources and Mines bulletin 2015