Contractors Wanted: Help NIOSH Advance Research to Protect Workers from Silica

Posted on by Chaolong Qi, PhD
  • Are you a contractor whose company has at least three years of field experience cutting fiber cement siding with a circular saw?
  • Has your company installed fiber cement siding on at least three large residential jobs?
  • Do you have an upcoming job where fiber cement siding will be cut and installed for at least eight hours per day over a course of three days?

If you answered “Yes” to these three questions then WE NEED YOU! 

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.  


Click the image to see a demonstration of Dr. Qi’s research.

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[i]. 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 (see the figure below). 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. 

NIOSH researcher demonstrating sampling devices

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 or use the blog comment box below. 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
*References to products or services do not constitute an endorsement by NIOSH or the U.S. government.

[i] Lofgren DJ, Johnson DC, Walley TL [2004]. Silica and noise exposure during installation of fiber cement siding. Journal of Occupational and Environmental Hygiene, 1: D1–D6 

Posted on by Chaolong Qi, PhD

15 comments on “Contractors Wanted: Help NIOSH Advance Research to Protect Workers from Silica”

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    It is very interesting your studies, I am working in indoor pollution and I need an equipment similar to what you show in the picture Could you tell me the mark and the technic specification of it

    Thank you

    The equipment clipped to the worker’s belt and worn at his waist is a battery-operated sampling pump, which is operated at a flow rate of 4.2 liters/minute (L/min) (model 224-PCXR8, SKC, Inc., Eighty Four, PA. The pump was connected via Tygon® tubing and a tapered Leur-type fitting to a pre-weighed, 37-mm diameter, 5-micron (μm) pore-size polyvinyl chloride filter supported by a backup pad in a three-piece filter cassette sealed with a cellulose shrink band (in accordance with NIOSH Methods 0600 and 7500). The front portion of the cassette was removed and the cassette was attached to a respirable dust cyclone (model GK2.69, BGI Inc., Waltham, MA). At a flow rate of 4.2 L/min, the GK2.69 cyclone has a 50% cut point of (D50) of 4.0 μm [BGI 2011]. D50 is the aerodynamic diameter of the particle at which penetration into the cyclone declines to 50%. The cyclone was clipped to the sampled cutter’s shirt near his head and neck.

    ***References to products or services do not constitute an endorsement by NIOSH or the U.S. government.***

    Shouldn’t the sampling media be placed higher?

    We are using the same sampling train using Gilian air sampling pumps.

    ***References to products or services do not constitute an endorsement by NIOSH or the U.S. government.***

    The picture shown in the blog is for demonstration only. In practice, the collection device (filter cassette, charcoal tube, etc.) should be placed on the shirt collar or as close as practical to the nose and mouth of the employee’s breathing zone (i.e., in a hemisphere forward of the shoulders within a radius of approximately nine inches). For more details please refer to the OSHA Technical Manual (OTM) at

    While we only have brief experience cutting fiber cement, White Mountain Constructions and our crew are always looking for ways to better protect our health in Pennsylvania. Hope this works out

    Hello, i am general contractor. We are cutting fiber cement almost everyday. We know its dangerous but we trying to protect ourselves as possible!
    Contact me if you want info!

    I have been back and forth between vinyl and fiber cement siding, but I think I’m going to go with vinyl. The huge benefit from vinyl is that I can install it myself, it’s cheap, and most of all it doesn’t require paint! I do not like painting, as it is so time consuming, so vinyl siding is the perfect alternative to me.

    I am a huge proponent for better methods. We are experimenting with a variety of options, focusing mostly on exhaust and ventilation. We have seen better results from using aerosol monitors than from sampling trains, simply because you can adapt as necessary. Additionally, the carpenters can see how much particulate, and the size, that is going into their respiratory system.
    I would be willing to share our results as well as participate in some studies.

    Mike H.

    This is a great post. I like this topic. This site has lots of advantage. I found many interesting things from this site. It helps me in many ways. Thanks for posting this again..

    I am recommending universal mask wearing for the construction industry due to Coronavirus, Hantavirus and silica dust exposure. COVID 19 has given us a reason to travel to and from work masked or covered up. SD 6′ and hand washing protocol. I am recommending universal mask wearing to continue for the construction industry. Respiratory equipment is job task specific and selection requires a qualified person, but the whole construction industry should have access to N95 or better protection. They should wear a mask all the time on the job and in travel. 6 months after COVID 19 has been vaccinated, they can stop traveling with respiratory protection. After COVID 19 is vaccinated, the respirator wearing should continue in construction because men consume soil orally during excavation, they inhale and ingest silica dusts during concrete phase and we all know that the stairwells collect a mixture of fumes, vapors, dusts for all the workers walking up and down to be exposed. A concrete contractor moves from job to job. The worker is exposed to silica all the time or soils at an excavation, all the time. If all labor has N95 or better for general use available, the health of the whole construction industry will improve. That is about 7-10 million workers not getting exposed to airborne contaminants. There should be enough respirators so we can enforce this rule. We, in construction, would have a lower exposure rate than other industries, if we had the masks. We know how to deal with every kind of dangerous condition. We are missing access to respirators. Construction needs a supply of NIOSH verifiable respirators. We can keep the transmission rate down better than any other industry. With no approved equipment, we will fail too. Thank you for the opportunity to be heard.

    Great article. It was very useful to read your facts. Thank you for sharing them with us.

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Page last reviewed: June 12, 2015
Page last updated: June 12, 2015