Preliminary findings in a study to evaluate exposure, health effects and control of respirable crystalline silica (RCS) in Queensland quarries

Exposure to respirable crystalline silica (RCS) is a major concern in quarries and mines. Studies in the UK and USA, and the reduction in occupational exposure standards (ES) support this view. This paper presents preliminary findings of an ongoing study of RCS exposure in quarries in Queensland. Twenty six quarry workers, several from each of 5 quarries were monitored for RCS for a range of job types. The current eight hour exposure standard (ES) of 0.1 mg/m3, or the relevant ES adjusted for extended shift lengths, was only met in one of the 5 quarries measured. Of concern was the average exposure at two of the quarries which exceeded 0.1 mg/m3, and at one quarry 2 measurements exceeded 0.25 mg/m3. These high measures were for an excavator saw operator and a stone mason. The results of spirometry testing indicated moderate obstruction of airways in some cases which may have been acerbated by exposures to higher concentrations of RCS. Real time and particle size airborne dust analysis showed that control measures such as airconditioned vehicle cabins are not necessarily effective in preventing exposure to RCS. Preliminary results from the installation of an air cleaning device (RESPA) indicated that this process has the potential to reduce the cabin exposure to RCS by between 2 and 12 times depending on the size of the airborne particles being measured. Preliminary analysis has indicated a possible relationship between loss of lung function and exposure to RCS. However more assessment and analysis is required before a definitive conclusion can be made.