Analysis of Respirable Silica Exposure During Lime Stabilization Roadway Construction Operations

Research Trainee: Beauregard Middaugh, PhD Student, School of Health Sciences at Purdue University

Faculty Researcher: Bryan J. Hubbard, PhD, Assistant Professor of Building Construction Management at Purdue University

The purpose of the proposed research is to 1) determine the respirable dust and silica exposure of workers during a typical roadway construction, soil stabilization project, 2) identify systematically the contributions of multiple dust-producing equipment to general laborer exposure using real-time respirable dust monitoring and Global Positioning System (GPS) tracking, 3) utilize induced sputum cytology to determine if an inflammatory response is elicited by calcium oxide in lime during an eight- hour workday, and 4) develop a best work practice educational video for lime soil stabilization using video exposure monitoring and supporting commentary.

The study will be performed onsite for three, eight-hour days, and will include the following individuals: general laborer, tilling machine operator, grader operator, and two lime truck drivers. A traditional eight-hour exposure assessment of respirable dust and silica (15 filter samples) will be collected for these individuals. In addition, real-time respirable dust monitoring and GPS tracking of the laborer each sampling day will provide a systematic approach for evaluating the contribution of specified equipment to exposure. Utilizing this information, best work practices and control priorities can be determined for each mobile piece of dust-producing equipment. Video exposure monitoring of the general laborer and tiller operator (six real-time samples and six in-line filter samples) will be used to in conjunction with data recorded for real-time respirable dust concentrations to develop a video to illustrate best work practices. Findings from the exposure assessment will then be used with these real-time videos to promote proper use of equipment and explain potential control solutions.

In addition, pre and post shift induced sputum samples (12 sputum samples) for the general laborer and tilling operator will provide data to assess the mixed dust exposure (i.e. silica and calcium oxide). As a marker of effect, changes in cell counts within the induced sputum will allow researchers to determine if dust exposure is in fact compounded by an inflammatory response elicited by the calcium oxide in lime. Calcium oxide full-shift air sampling will be performed to evaluate a potential relationship between exposure and inflammatory response (12 filter samples). This may provide important insight into whether specific health standards should be applied to this operation.


Publications resulting from this project:
Hubbard B, Huang Q, Caskey P, Wang Y. Safety awareness educational topics for the construction of power transmission systems with smart grid technologies. Australasian Journal of Construction Economics and Building. 2013;13(3):114-127. doi: 10.5130/AJCEB.v13i3.3385.

Hubbard B, Middaugh B. Leveraging Bluetooth Consumer Electronics as Proximity Sensors to Construction Hazards. International Journal of Construction Education and Research. 2013;9:117–131. doi: 10.1080/15578771.2012.692758.

Middaugh B, Hubbard B, Zimmerman N, McGlothlin J. Evaluation of Cut-Off Saw Exposure Control Methods for Respirable Dust and Crystalline Silica in Roadway Construction. Journal of Occupational and Environmental Hygiene. 2011;9(3):157-165. doi: 10.1080/15459624.2012.658265.

Research trainee’s current position:
Beauregard Middaugh completed his PhD in 2012 and he is now a Safety Specialist & Industrial Hygienist at Indiana University.