CONN-OSHA consultation was asked to evaluate a worker’s exposure to respirable crystalline silica (RCS) during rock drilling tasks. The worker’s company had been hired to drill and blast the existing granite rock as part of the site work involved in preparing for the construction of a new building. Exposure to respirable crystalline silica is associated with elevated rates of lung cancer.

On the day of the initial survey the employee manually operated a vehicle mounted drilling rig and was found to have a high exposure to crystalline silica. The employer was asked to evaluate feasible engineering controls that could reduce exposure to RCS.

After contacting the equipment manufacturer’s vendor, the employer implemented additional controls:

• Increased the volume of water supplied to the drill bit,
• Replaced the dust shroud at the point of impact and supplementing the existing chutes with an additional elongated sleeve at both the front and rear of the machine where debris is expelled.

The employees’ exposure to silica was greatly reduced after the implementation of these controls

Collaborating with the On-Site consultation program encouraged the company to implement similar dust controls at other job sites.

Learn how OSHA's On-Site Consultation program can benefit your business by calling 800-321-OSHA (6742) or visit www.osha.gov/consultation.

OSHA's On-Site Consultation Program offers no-cost and confidential occupational safety and health services to small and medium-sized businesses in all 50 states, the District of Columbia, and several U.S. territories, with priority given to high hazard worksites. Consultants from state agencies and universities collaborate with employers to identify workplace hazards and how to fix them, provide advice for compliance with OSHA standards, train and educate workers, and assist in establishing and improving safety and health programs. On-Site Consultation services are separate from OSHA enforcement efforts.