The objective of this study was to evaluate the level of exposure to respirable crystalline silica (RCS) among concrete finishers and to identify the size distribution of particles from concrete finishing work at apartment complex construction sites.
Active personal air sampling (n = 129) was conducted at eight apartment complex construction sites by using filters with aluminum cyclones. Local air sampling for the size distribution of the particles (n = 6) was carried out by using a mylar substrate with cascade impactors. Crystalline silica was analyzed by Fourier-transform infrared spectroscopy (FTIR). The collected personal samples were sorted by the type of job task (concrete chipping, grinding, and plastering) at four types of workplaces (exterior walls, walls inside apartment units, staircases, and underground parking lots).
The geometric mean (GM) of the RCS concentration according to type of job tasks was highest in concrete grinding (2.06 mg m-3), followed by concrete chipping (0.12 mg m-3), and plastering work (0.003 mg m-3). The GM of the RCS concentration in concrete grinding work differed by the type of workplaces. The highest concentration of RCS was measured in the staircases (4.18 mg m-3), followed by the inside walls of apartment units (2.76 mg m-3), underground parking lots (1.30 mg m-3), and exterior walls (0.89 mg m-3). The mass fraction of inhalable, thoracic, and respirable crystalline silica from concrete chipping was 73.9%, 40.2%, and 17.9% and 76.0%, 46.3%, and 19.7% from concrete grinding, respectively.
Concrete finishing workers at apartment complex construction sites are exposed to unacceptably high concentrations of RCS. To protect concrete finishing workers’ health, dust-minimizing construction methods and the use of local exhaust ventilation system or wet method simultaneously with high-efficiency respirators must be applied. Further efforts to reduce total work time, and use air-purifying full-faced respirators should be made.