Multi-element analysis of airborne particulate matter from different work tasks during subsea tunnel rehabilitation work

ABSTRACT

Tunnel rehabilitation work involves exposure to various air contaminants, including airborne particulate matter (APM). Little is known on the contents of different chemical components of APM generated during tunnel work.

The objective of the present study was to characterize exposure to APM and various elements for different job categories in different size fractions of APM during a subsea tunnel rehabilitation project carried out in Western Norway. Personal as well as stationary samples of inhalable, thoracic and respirable dust were collected from workers divided into 11 different job categories based on work operations performed, and air concentrations of a range of elements were determined using high-resolution inductively coupled plasma-mass spectrometry (HR-ICP-MS).

Overall, APM concentrations were low, but with some measurements exceeding the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) for inhalable particles, and considerable proportions of respirable and especially inhalable APM exceeding 10% of the TLVs. For most elements, air concentrations measured were quite low, in the ng/m³ range, except for the major crustal elements Si, Fe, Al, and Mg, which were found to be in the µg/m³ range. Asphalt millers overall had the highest exposure levels for APM and most measured elements; for instance, mean concentrations of V, Rb, and Mn were 380, 210, and 2000 ng/m³ in inhalable and 33, 44, and 310 ng/m³ in respirable APM. Mounting PVC membrane seemed to generate elevated levels of Cr, Zn, Sn, Pb, Sb, As, Mn, Fe, and Ni, whereas typical bedrock elements were elevated during drilling activities compared to the low exposed categories lead car drivers, foremen/surveyors, drivers of heavy-duty vehicles, and electricians. Overall, stationary samples contained lower amounts of dust and elemental constituents compared to personal samples. Elemental air concentrations were highly variable with occasional elevated values for APM and certain elements, particularly Cr and Zn.

KEYWORDS:

• Airborne particulate matter
• metals
• occupational exposure
• trace elements
• tunnel rehabilitation work

Acknowledgments

We thank the construction workers for their participation. This project could not have been accomplished without their positive attitude and carrying the sampling equipment and providing technical assistance during the sampling. We thank Torbjørn Aae for technical assistance during the sampling of airborne dust at the work place. We also thank Syverin Lierhagen, Department of Chemistry, NTNU for performing the ICP-MS analyses and for general laboratory assistance, and Eiliv Steinnes for reviewing the article and providing valuable input.

Funding

The study was partly financed by the Norwegian Public Roads Administration.