Rates of severe coal workers' pneumoconiosis -- also known as black lung disease -- among coal miners have been on the rise recently despite regulations on exposure to dusts associated with mining.

Researchers believe the higher rates of more severe lung disease may be due to greater exposure to silica, likely as a byproduct of going after ever-narrowing coal seams that require cutting through more rock to reach. Silica dust is much more toxic to the lungs, but little is known about its contribution to black lung disease at the molecular level, and researchers don't know how silica and coal or other dusts together might interact to influence the development of disease.