Six hundred and fifty one Norwegian male construction workers were followed for a mean of 6 years with spirometric measurement and assessment of their occupational exposure to total dust, respirable dust, α-quartz, volatile organic compounds, oil vapour, oil mist, formaldehyde, nitrogen dioxide, and carbon monoxide. Compared with a low exposure reference group of outdoor (non-tunnel) workers, tunnel workers showed a decrease in lung function between the first and last spirometric assessments. The excess annual decline in forced expiratory volume in 1 second (FEV₁) in non-smoking tunnel construction workers was 26 ml for drill and blast workers, 31 ml in tunnel concrete workers, and 21 ml in shotcreters. The decrease in FEV₁ was found to be significantly associated with all exposures. Multiple linear regression modelling for decline in FEV₁ showed that cumulative exposure to nitrogen dioxide had the strongest association of all the agents.

This study demonstrates a decline in lung function in tunnel construction workers exposed to nitrogen dioxide and other agents over a 6 year period. It highlights a need for decreasing occupational exposure to nitrogen dioxide, and also to respirable dust and α-quartz, which could be achieved by reducing diesel exhaust emissions and deployment of respiratory devices to protect workers.