Respirable crystalline silica exposures among stone workers in Ireland

Respirable crystalline silica (RCS) concentrations are related to the crystalline silica content of the rock being worked, which means stone workers working with high-silica-content materials can be exposed to excessive levels of respirable dust containing crystalline silica. Little information exists on the RCS exposure concentrations, work practices, and worker knowledge of the hazards associated with RCS exposure among stone workers in Ireland. The objective of this study is to collect information on health and safety practices and worker knowledge of the health risks associated with RCS among stone workers using a questionnaire survey. To design and execute a pilot study to collect personal RCS exposure measurements among a group of restoration stone workers. A self-report quantitative questionnaire was designed based on previously published work and administered to a convenience sample of 130 stone workers engaged in various stonework trades throughout the Republic of Ireland. The questionnaire was designed to collect information on worker demographics, work practices, health and safety practices, knowledge of the risks associated with RCS, and diagnosed respiratory illnesses. Personal exposure measurements of respirable dust were collected using direct reading and gravimetric sampling methods from a group of 14 restoration stone workers working at historic sites throughout Ireland. Respirable dust samples were further analysed for RCS. A questionnaire response rate of 48 % (n = 63) was achieved. Sixty-six percent of respondents reported regularly using power tools with high-silica-containing materials. The most frequently employed control measure used was respiratory protective equipment (RPE) (85 %), followed by general ventilation (60 %), and more than half of the respondents (58 %) used sweeping as their primary method of cleaning up their work area. Geometric mean 8-h, time-weighted average (TWA) concentrations of RCS ranged from 0.002 to 1.38 mg/m3, higher concentrations were reported for work involving sandstone, with 78 % of exposure samples exceeding the Irish occupational exposure limit value (OELV) of 0.1 mg/m3. A training program focusing on inhalation exposure risks associated with RCS and effective engineering controls is needed for this occupational group. The results from this pilot study will be used to design a larger study, involving more exposure measurements, to investigate determinants of RCS exposure within restoration stone masonry. This will aid in the design of a technical intervention for high-risk exposure tasks, involving work with power tools and high-silica-content materials.