This study investigated the occupational exposure to crystalline silica dust and diesel exhaust in the Anneberg-Skanstull tunnel project, particularly targeting the use of Tunnel Boring Machines (TBMs) and drill and blast methods. The aim of the thesis was to study the nature and level of exposure to silica dust and diesel engine exhaust. A mixed-methods approach was used, incorporating both quantitative and qualitative research techniques. Quantitative data were collected firstly, through literature review and then using air sampling equipment to measure the concentrations of respirable crystalline silica and nitrogen dioxide on an activity or task-based sampling strategy. Qualitatively, unstructured interviews alongside observations were conducted to gather detailed insights into workers' experiences and practices concerning exposure to these hazardous substances.

Considerable exposure to RCS occurred during maintenance and inspections and other manual drilling-related activities such as the conveyor and rail extension works at the TBM. The use of electrically powered equipment reduced diesel exhaust exposure at the TBM, yet sporadic high exposures occurred due to inadequate ventilation or improper practices like idling at drill and blast locations. Gaps in worker awareness and unsafe practices were identified, indicating the need for improved awareness of exposure mechanisms and long-term implications of exposure. Stricter supervision and remodification of control measures or integration of smart safety systems for future TBMs that do not rely on the operator for them to operate efficiently, besides a proper risk assessment that would involve seemingly minor dust generating activities were proposed as measures to reduce future exposure.

This study concluded that, due to the lack of baseline measurements for TBM technology, the efficiency of the TBM in reducing dust could not be assessed. However, the current measurements will serve as a baseline for future evaluations.