Dust Control Handbook for Industrial Minerals Mining and Processing

manually removing the bags and placing them onto a conveyor belt. Figure 8.10 shows acomparison of the respirable dust exposure of these two workers while performing the same jobfunction when different control techniques were implemented (system type 1–4). The point to behighlighted from this testing was that regardless of the system being evaluated, worker #2'srespirable dust exposure was always significantly less than that of his coworker (worker #1).The main reason for these differences was worker #1 performed his job function in a roughmanner relative to worker #2, who performed the exact same tasks in a very conscientious orcareful manner. Ultimately, this resulted in worker #2's respirable dust exposure beingapproximately 70 percent less than that of his coworker.Figure 8.10. Comparison of two workers’ respirable dust exposure while performingtheir job function with different control techniques being implemented.One key element in how worker #2 performed his tasks was the way he manually closed the bagvalve with his hand as he removed the bag from the fill station and transferred it to the conveyor(Figure 8.11). This technique was believed to be instrumental in lowering the worker'srespirable dust exposure. Comparing the difference between these two workers indicates theimpact that individuals can have on their dust exposure based upon how they perform their jobfunction.216 Controls for Secondary Sources