Engineering Controls
As mentioned earlier, if possible, we want to do something about the hazard first. Then we don't have to worry so much about employee behaviors. Engineering controls attempt to do that.
If silica products are used, OSHA requires engineering controls to be used first wherever possible. This type of control involves a mechanical process to eliminate or reduce the amount of silica dust.
The most effective way to eliminate the silica hazard is to eliminate the silica! Doing that is not possible for many masonry operations, but engineering controls are possible and especially important for many applications.
For instance, where abrasive blasting is done outside, substitution of silica with some other material can be used. Substituting the silica means using a different, safer material, like plastic beads, corn cobs, walnut shells, etc., in place of the silica-containing substance.
There are two basic types of engineering control methods:
- Wet methods: As we mentioned earlier, wet methods for cutting, drilling, hammering and grinding is the most effective method for controlling airborne silica dust because it controls the exposure at its source. In most cases, wet methods keep exposures below the allowable limit.
- Dry methods: The most common dry control method is vacuum dust collection (VDC). This engineering control method can significantly reduce silica levels, but may not reliably keep them below 0.1 mg/m3 as an 8-hour TWA. VDCSs include a dust collector (hood or shroud), vacuum, hose and filter(s).
Knowledge Check Choose the best answer for the question.
3-2. What is the most effective method for controlling airborne silica dust because it controls the exposure at its source?
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