Introduction High airborne concentrations of respirable quartz have been reported from workers in construction, foundries, and quarries. Current exposure levels in prevalent but presumably lower exposed jobs have been less examined.

Objectives To quantify the current exposure concentrations of respirable dust and quartz across prevalent occupations with expected moderate to high levels of exposure in Denmark. A second aim was to identify determinants of respirable quartz exposure across occupations.

Methods 189 full-shift personal samples of respirable dust within 11 occupations were sampled and analysed for quartz content with infrared spectrometry. Determinants for respirable quartz like use of tool and location of worksite were analysed in mixed linear effect models.

Results The overall geometric means (geometric standard deviation) for respirable dust and quartz were 220 µg/m3 (4.19) and 16 µg/m3 (4.07), respectively. The highest quartz concentrations were observed among stone cutters and carvers (93 µg/m3 (3.47)), and metal melters and casters (61 µg/m3 (1.71)). Use of power tools increased exposure concentrations by a factor of 3.5. Of the total variance, variability between jobs explained 27%, variability between companies within jobs explained 29%, and variability between workers within a job within a company explained 14%. 30% of the total variance was explained by day-to-day variability.

Conclusion A number of jobs in this study had average exposure levels to respirable quartz above 50 µg/m3. Use of power tools were the main determinant. Preventive measures to lower excess risk of lung cancer among these workers are still needed.