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Why Does Water Droplet Size Matter for Silica Dust Suppression?
The hazards of respirable silica dust are well known. There are now regulations and suggested engineering controls in place to help protect workers in various industries from these hazards. Using a water delivery system to boost dust suppression is common in both construction and general industry; however, there are many nuances to proper respirable dust suppression using water.
Droplet size is a major determinant in the effectiveness of dust suppression when using a water delivery system. While water alone may be able to suppress visible dust relatively well, it is not effective in suppressing harmful respirable silica particles–this is due, in part, to the standard droplet size delivered through most water systems. Typically, water droplets sprayed into the air range from 200 μm to 1000 μmin size. When these larger particles move through the air, they push away lighter silica particles, causing silica dust to remain airborne, or “fugitive.” This issue is called the “slipstream effect” because the silica particles literally slip past the water stream, avoiding suppression.1
