Health and Safety, ICU Environmental, Houston, Texas, USA.
J Occup Environ Hyg. 2010 Apr;7(4):245-51. doi: 10.1080/15459620903579695.
Respirable crystalline silica dust exposure in residential roofers is a recognized hazard resulting from cutting concrete roofing tiles. Roofers cutting tiles using masonry saws can be exposed to high concentrations of respirable dust. Silica exposures remain a serious threat for nearly two million U.S. construction workers. Although it is well established that respiratory diseases associated with exposure to silica dust are preventable, they continue to occur and cause disability or death. The effectiveness of both a commercially available local exhaust ventilation (LEV) system and a water suppression system in reducing silica dust was evaluated separately. The LEV system exhausted 0.24, 0.13, or 0.12 m(3)/sec of dust laden air, while the water suppression system supplied 0.13, 0.06, 0.03, or 0.02 L/sec of water to the saw blade. Using a randomized block design, implemented under laboratory conditions, the aforementioned conditions were evaluated independently on two types of concrete roofing tiles (s-shape and flat) using the same saw and blade. Each engineering control (LEV or water suppression) was replicated eight times, or four times for each type of tile. Analysis of variance was performed by comparing the mean airborne respirable dust concentrations generated during each run and engineering control treatment. The use of water controls and ventilation controls compared with the "no control" treatment resulted in a statistically significant (p < 0.05) reduction of mean respirable dust concentrations generated per tile cut. The percent reduction for respirable dust concentrations was 99% for the water control and 91% for the LEV. Results suggest that water is an effective method for reducing crystalline silica exposures. However, water damage potential, surface discolorations, cleanup, slip hazards, and other requirements may make the use of water problematic in many situations. Concerns with implementing an LEV system to control silica dust exposures include sufficient capture velocity, additional weight of the saw with the LEV system, electricity connections, and cost of air handling unit.
住宅屋顶工人在切割混凝土屋顶瓦时，会接触到可吸入结晶硅尘，这是一种公认的危害。屋顶工人使用砖石锯切割瓷砖时，可能会接触到高浓度的可吸入粉尘。在美国，近 200 万建筑工人仍然面临着硅尘暴露的严重威胁。尽管众所周知，与接触硅尘有关的呼吸道疾病是可以预防的，但它们仍在继续发生，并导致残疾或死亡。本研究分别评估了一种市售局部排气通风（LEV）系统和水抑制系统在降低硅尘方面的有效性。LEV 系统排出了 0.24、0.13 或 0.12m³/sec 含尘空气，而水抑制系统向锯片提供了 0.13、0.06、0.03 或 0.02L/sec 的水。采用随机区组设计，在实验室条件下，对两种类型的混凝土屋顶瓦（S 形和平面形）使用相同的锯片，分别评估了上述条件。每种工程控制（LEV 或水抑制）都复制了 8 次，或每种类型的瓷砖复制了 4 次。通过比较每次运行和工程控制处理过程中产生的空气中可吸入呼吸性粉尘的平均浓度，进行方差分析。与“无控制”处理相比，使用水控制和通风控制会导致每块切割瓷砖产生的呼吸性粉尘浓度有统计学意义的（p<0.05）降低。水控制的呼吸性粉尘浓度降低了 99%，LEV 的呼吸性粉尘浓度降低了 91%。结果表明，水是一种有效的降低结晶硅暴露的方法。然而，水损害的可能性、表面变色、清理、滑倒危险和其他要求可能会使水在许多情况下的使用变得复杂。在实施 LEV 系统控制硅尘暴露方面，存在一些顾虑，包括足够的捕获速度、带 LEV 系统的锯的额外重量、电力连接和空气处理单元的成本。
