Posted on the NIOSH Science Blog March 26, 2013

The National Institute for Occupational Safety and Health (NIOSH) is currently testing low-cost solutions for protecting workers from silica exposure when cutting fiber cement siding. You can help us test a dust control and at the same time add to the research that supports and advances the prevention of silicosis.   

Fiber cement siding and silica

Fiber cement siding is a popular product in home construction. Many builders select this siding because it is a weather-resilient material that does not generally attract insects or need to be painted as frequently as other common siding materials. However, fiber cement siding when cut can create fine dust particles containing silica that when breathed in, can lead to serious lung diseases, such as silicosis.   

The only published study on fiber cement cutting suggests that the fine dust particles result in high concentrations of silica exposure, putting workers at risk for silicosis. We verified this in a field test and found similar exposures when the siding was cut without using dust controls. We then cut the siding in an isolated chamber in our laboratory and found that many of the generated dust particles are small enough to reach the deepest part of the lung.    

Having found that cutting fiber cement siding involved the potential workplace hazard of respirable silica dust exposure, we wanted to find a simple, effective solution to reduce dust exposures. For this study, we have been partnering with the major manufacturers of fiber cement siding, including James Hardie and CertainTeed.*  Some of these manufacturers recommend using High-Efficiency Particulate Air HEPA vacuums with power saws to cut fiber cement siding. However, the effectiveness of these recommendations has not been tested.   

Our lab tests indicate that connecting a regular shop vacuum to a circular saw may provide a simple and low-cost solution to the problem of silica exposure from cutting fiber cement siding.  Now we need to test this solution at real work sites. This is where you come in.    

What Is involved with helping NIOSH?   

As workers cut fiber cement siding, NIOSH researchers would like to test the air in the workers’ personal breathing zone during a work shift. During the test days, NIOSH researchers will ask some workers to wear a small device (sampler and pump) on their belt or vest with a filter clipped to their collar. The samples would be changed at mid-shift or lunch time. At the end of the shift, the samples will be collected and sent to a lab for analysis. NIOSH has experience collecting personal air samples on construction sites, and we will do our best to limit interruptions in work activities.   

We will bring circular saws, diamond blades, and shop vacuums (equipped with high efficiency filters) for use in the study, as well as the sampling devices and materials needed to collect the air samples. The circular saw will be connected to a shop vacuum by a flexible vacuum hose. We will record the flow rate going through the vacuum. The vacuum will be setup to automatically turn on when the circular saw is started. Workers can do their jobs as they normally would.  

In addition to measuring personal dust exposure, the NIOSH team will measure the wind direction and speed using a portable weather station and will count the number of siding boards cut. The dust produced from cutting the siding will be collected to determine its silica content. General observations regarding things like other dusty operations that are occurring nearby will also be noted. NIOSH will write a technical report on the effectiveness of the dust control for each field evaluation conducted. Contractors will be given the opportunity to review the report for trade secrets and potential technical inaccuracies. Personal air sampling results will be provided to the employees who participate. The final field survey reports will be publicly available on the NIOSH website. Examples of our field survey reports can be viewed at:   

NIOSH research is limited to the scope of the study described above. Participation is voluntary and you can opt out of the study at any time. If you are  interested in participating, we are happy to answer any questions you may have. Because the NIOSH researchers conducting this study are based in Cincinnati, job sites located in Ohio, Kentucky, and Indiana would be easiest to get to.  However, all offers of assistance are appreciated and all sites will be considered.    

Why should I do this?

By participating in this study, you can help a national effort to reduce exposures to hazardous silica dust when cutting fiber cement siding. The results of this study will help NIOSH and its partners make best practice recommendations for protecting workers and others who cut fiber cement siding.

Since 1976, NIOSH has conducted a number of assessments of control technologies on silica dust. For more information on NIOSH’s efforts to reduce exposure to silica dust, refer to our website at To learn more about occupational safety and health topics and NIOSH visit the NIOSH website at   

How do I sign up?

If you want to help or learn more about this study, you can e-mail us at Thank you in advance for helping to protect workers!    

Chaolong Qi, PhD   

Dr. Qi is a researcher in the NIOSH Division of Applied Research and Technology