IH Airborne Exposure Monitoring for Respirable Crystalline Silica Related to Concrete Cutting Procedures and Demolition Activities

1574 

Professional Poster 

J Koehn¹

¹Jan Koehn, M.S., CIH, Inc., Houston, TX

Ms. Jan Koehn, CIH  
Jan Koehn, M.S., CIH, Inc.

Performance of occupational exposure assessment of Respirable Crystalline Silica (RCS) including use of both qualitative and quantitative evaluation of actual airborne personal workplace exposures related to concrete cutting procedures using various types of construction equipment and also project demolition work were observed and recorded on behalf of the client. The objective of this work was to determine compliance with the updated OSHA Permissible Exposure Limit (PEL) and published regulatory standard requirements for Respirable Crystalline Silica (RCS) promulgated for the construction industry with anticipated direct impact on the contractor's work operations. This was accomplished through the development and implementation of site-specific sampling strategies by a CIH for personal and area assessments to provide documentation of airborne workplace exposure data

Based on standard use of numerous saws and also remote control equipment for concrete cutting work and separate demolition activities with heavy construction equipment including enclosed cabs, design and implementation of representative airborne sampling strategies for RCS were addressed for separate outlined construction projects with identified equipment utilized by the client for scheduled job sites during full work shift and/or partial period time intervals in 2019. Direct site observations were additionally recorded for construction activities and equipment operation on projects, job positions and accepted work practices and procedures, and control measures employed including standard integrated wet methods during saw equipment use as well as remote control operation. Sampling strategy development was undertaken for the identified Respirable Crystalline Silica (RCS) hazard for specified contractor personnel and area samples with notation of existing controls and current operations, and observed site work procedures to assist with airborne monitoring data interpretation and site documentation for verification of company health and safety programs.

The project assessment strategy addressed collection of personal airborne breathing zone samples on identified job positions (i.e., operators) and adjacent area sample locations involving various methods of saw cutting, concrete demolition, and specified material removal on construction sites with lab analysis for Respirable Crystalline Silica (RCS). The validated industrial hygiene sampling and analytical methods were: NIOSH 0600 for respirable particulates using SKC aluminum cyclones, and NIOSH 7500 for crystalline silica with requested laboratory analysis for cristobalite, quartz, and tridymite forms and total airborne RCS exposure. Personal pumps were pre- and post calibrated with a primary standard and adjusted to the flow rate recommended for proper air sample collection using SKC cyclones for breathing zone respirable particulate data in addition to specified crystalline silica. Filter cassette media (i.e., pre-weighed 37 mm PVC) was used for collection and processing to a local accredited AIHA laboratory, and field blank samples were prepared for quality control. Separate use of SKC Parallel Particle Impactors (PPI) for side-by-side airborne sample collection was also included for relative comparison related to exposure assessment. Notation of work site conditions and job related activities with potential impact on airborne exposures was performed. These parameters included: weather, climate, temperature, relative humidity, general wind direction and speed, visibility, and also outlined cutting and material removal, construction equipment types for site operation and noted use, amounts and location of concrete disturbance operations and job position activity variables including observed saw use, frequency, and duration of specific operations and control measures employed.

Occupational exposure assessment activities including airborne monitoring and job position observations of concrete saw cutting and heavy construction equipment for demolition were completed with documentation involving ambient weather and climate conditions and notation of work practices and procedures and control measures employed. Industrial hygiene monitoring results were compared with the OSHA regulatory Construction standard for RCS and other published technical guidelines to assess and manage workplace airborne exposures. Breathing zone personal monitoring results for crystalline silica were generally below the existing OSHA PEL and/or Action Level for RCS in the Construction industry for noted operations. Observations verified use of integrated wet methods for concrete cutting and drilling operations as well as ventilation to limit production of airborne exposures. Outside ambient environments provided dilution ventilation depending on existing climate and weather conditions. For segregated indoor environments, supplemental ventilation was employed to lower airborne levels. Other variables included: quantity of concrete cutting operations performed; specific construction and demolition equipment; vacuum collection of produced slurry, overall dust and debris collection; and other airborne exposure variables. A company written Respiratory Protection Program is enforced. Industrial hygiene monitoring data provided verification of proper protection of employees and further limitation of airborne occupational exposures of personnel using controls.

Exposure Assessment Strategies

Construction

Sampling and Analysis