Fiber cement board is a construction material often used as siding in place of wood or vinyl.
Fiber cement board is made with a combination of wood fiber, finely ground silica sand,
and cement. When cutting through a board using a power
saw, the saw blade kicks up a cloud of dust. Exposure to high concentrations of silica
dust can be hazardous and can lead to a lung disease called silicosis.
Two exposure studies have found that the amount of silica dust in the air while cutting fiber
cement siding can reach hazardous levels. In this project we want to study how to control
the dust and reduce exposure. I wanted to measure the dust cloud from cutting
fiber cement boards. I was interested in learning about the size of the dust, how it was generated
and how much silica was there. So I ran tests in this enclosed automatic test chamber.
You can see a lot of dust coming through the saw's exhaust port.
I found that many of these dusts were respirable, meaning they were breathable and small enough
to penetrate the deepest parts of the lung. And these respirable dusts contained crystalline
silica. I tested several different controls, including
attaching the hose of a standard shop vacuum to the exhaust port of the saw.
Our lab results showed that connecting circular saws to a shop vacuum or a dust collector
captured about 80 to 90 percent of the dust across all sizes.
These results suggest that connecting a regular shop vacuum to a circular saw has a potential
to provide a simple and low-cost solution to the problem of silica exposure while cutting
fiber cement siding.