Abstract

Objectives
Tunnel construction workers are exposed to particulate and gaseous air contaminants. Previous studies carried out in the 1990s showed that tunnel construction workers were at increased risk of both short-term and long-term lung function decline. Since then, efforts have been made to reduce exposure. The objective of the present study was to investigate if current exposure may still cause short-term lung function impairment.

Methods
Tunnel workers work 12 days consecutively, and then they are off for 9 days. Ninety tunnel workers and 51 referents were examined with spirometry and questionnaires before their work period started and again 11 days later. Personal exposure to particles and a-quartz in the thoracic aerosol subfraction, elemental carbon and organic carbon, oil mist, nitrogen dioxide and ammonia was assessed on two consecutive days between the two health examinations.

Results
The geometric means air concentrations for particulate matter in the thoracic mass aerosol subfraction, a-quartz, oil mist, organic carbon and elemental carbon for all workers were 561, 63, 210, 146 and 35 µg/m3, respectively. After 11 days of work, the mean forced expiratory volume in 1 s (FEV1) in healthy participants had declined 73 mL (SD 173), p<0.001 in the tunnel workers, compared to 3 mL (SD 21), p=0.9 in the referents. Also, forced vital capacity (FVC) had declined significantly. Declines in FVC and FEV1 were significantly associated with exposure to organic carbon.

Conclusions
In spite of reduced levels of exposure in modern tunnelling operations, a negative impact on lung function was still observed.

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Comments

This study suggests that the diesel particulates may be more important than the silica, but we are not told what sort of rock was being tunneled

2/7/2015