The aim of the project is to assess respiratory health among rock drillers exposed to crystalline silica. The study shows a slight small airways dysfunction among the exposed workers compared to the referents.

They further have higher levels of surfactant protein D in serum, which may indicate an involvement of the pulmonary surfactant. They also have higher serum concentrations of matrix metalloproteinase 12 (MMP-12) compared to the referents, and the concentrations are related to cumulative exposure to crystalline silica. MMP-12 is considered to be involved in the development of emphysema.

In this study, pulmonary function and biomarkers of inflammation were studied in workers during ongoing exposure to crystalline silica. Further, gene expression in cells collected from the nose was studied. The aim of the study was to investigate associations between these health outcomes and current and cumulative exposure to crystalline silica. The health examinations were carried out as close to the workplaces as possible, preferentially at the end of the workday. Spirometry was conducted among all exposed workers and referents. Blood samples and brush samples from the nose were also collected for the determination of biomarkers.

High resolution pulmonary computer tomography (HRCT) was offered to the most highly exposed workers, conducted at various hospitals according to a standardized protocol. Alle exposed workers from the participating rock drilling companies, who complied with the inclusion criteria, were invited to the examinations. Subjects from the same companies, who had work tasks not associated with exposure, were invited to the study as referents. The cross-sectional study revealed differences in pulmonary health between exposed participants and referents, and a follow-up after two years was conducted in the respective occupational health services of the participating companies.  


The study shows small airways dysfunction in the exposed workers. They further have increased levels of surfactant protein D, indicating an impact of exposure on the surfactant of the lungs. The also have higher, dose-related levels of Matrix Metalloproteinase 12, which is known to be involved in the development of emphysema.

Two scientific papers have been published, and one is ready for submission.

Project group

Project leader: Bente Ulvestad

Dag Ellingsen, Nils Petter Skaugset, Thomas Clemm

In Collaboration with: Regional safety representatives (RVO)