National Pipeline Exposure Assessment

Specialty Consulting, Inc. (SPC) was engaged by National Pipeline (NPL) to provide equipment and technical support for an assessment of respirable crystalline silica (RCS) exposure. The goal was to evaluate worker exposure to airborne silica during construction activities.

The project addressed the new OSHA standard for RCS, which mandates that employers protect workers from RCS exposure above the permissible exposure limit (PEL) of 50 µg/m3, averaged over an eight-hour workday. Silica dust sampling and analysis were conducted in accordance with NIOSH Method 7500. Representative air was drawn through a 10-mm nylon cyclone and a 37-mm, 5-µm PVC pre-weighed membrane filter, placed in a closed-face cassette at a flow rate of 2.5 liters per minute.

Samples were collected from workers with the highest potential for exposure, primarily those operating saws to cut concrete, asphalt, or roadways. These workers were chosen due to the extensive cutting performed during their shifts. A smaller, detachable saw using water as a dust control method was employed during cutting. Workers also wore appropriate personal protective equipment (PPE), including steel-toed boots, face shields, N95 dust masks, reflector vests, gloves, long-sleeve shirts, pants, and hard hats.

Based on field observations and assessment findings, SPC recommended various engineering and administrative controls and PPE to reduce workers’ exposure to RCS.