The aim of this study was to build upon previous research; collecting further workplace exhaled breath condensate (EBC) samples and characterising the exposure to silica in each workplace to fully assess the usefulness of the method as a biomonitoring technique [1].

The results reported here were collected from three workplaces known to use silica-containing materials. EBC samples were collected pre and post shift from thirty workers and eleven controls. To characterise exposures in the workplaces

 static air samples as well as bulk dust samples were collected and analysed. A range of real-time particle counting instruments was also employed.

The volume of EBC collected was standardised for exhaled air volume (50 L) and samples were measured for a range of elements as well as silicon (Si) containing particles using single particle inductively coupled plasma tandem mass spectrometry (spICPMSMS). To differentiate between the high backgrounds and the particles it was necessary to process the spICPMSMS data using an open-source Python-based SP/SC ICP-MS data processing platform ‘SPCal’ [2]. The bulk samples collected were characterised for particle size distribution, elemental and respirable crystalline silica (RCS) concentration.

Overall, the results show that EBC is a useful biological matrix for assessing exposure to RCS in workplaces. Exposures were seen to increase through the working day, and there were differences between workers and workplaces. Compared with the control EBC samples all workplace EBC samples had higher concentration of Si-containing particles and the particles were slightly bigger, they also exhibited higher background silicon levels. Realtime monitors also showed the potential to capture task specific exposures and offer additional information/exposure data not previously available.