LCS Laboratory Inc. offers a specialized analytical method for Respirable Combustible Dust (RCD), developed to meet the growing regulatory need for accurate exposure assessment of diesel particulate matter (DPM) and carbonaceous respirable dust. This method integrates the sampling principles of NIOSH 0600 with a controlled combustion step adapted from ASTM D7348, providing a practical, defensible, and cost‑effective solution for industrial hygiene programs.
Background and Regulatory Context
Diesel exhaust has been recognized as a significant occupational hazard for decades. In 1988, the National Institute for Occupational Safety and Health (NIOSH) identified diesel exhaust as a suspected occupational carcinogen. The U.S. Environmental Protection Agency (EPA) later classified diesel exhaust as “likely to be carcinogenic,” reinforcing the need for reliable exposure monitoring. In 1990, the Canadian ad hoc Diesel Committee recommended that diesel particulate exposure be assessed using Respirable Combustible Dust (RCD), with an occupational exposure limit of 1.5 mg/m³ over an 8‑hour shift. This guideline has since been adopted by most mining provinces in Canada and remains a key benchmark for underground mining operations. Despite its regulatory importance, no standardized analytical method exists specifically for RCD. LCS Laboratory developed its modified NIOSH 0600 / ASTM D7348 method to fill this gap with a scientifically robust and operationally efficient approach.
Overview of the LCS RCD Method
The LCS method provides two primary results from a single air sample: Total Respirable Dust (TRD) and Respirable Combustible Dust (RCD). When requested, the remaining mineral fraction can also be analyzed for respirable crystalline silica, allowing clients to obtain three critical exposure metrics from one filter. This approach enhances data quality, reduces sampling costs, and supports more comprehensive exposure assessments.
Industries and Applications
This method is ideal for underground mines, surface mines, tunnels, maintenance shops, industrial facilities with diesel equipment, and any environment where both mineral dust and diesel particulate are present. It supports baseline surveys, compliance monitoring, ventilation assessments, and engineering control verification.
Air Sampling Procedure
Sampling follows the established principles of NIOSH 0600. Air is drawn through a pre‑weighed 37 mm PVC filter equipped with a respirable dust cyclone to ensure proper size selection. Typical sampling durations range from 2 to 8 hours, depending on expected dust concentrations and site conditions. After sampling, filters are sealed, documented using request form, and shipped to LCS Laboratory under standard chain‑of‑custody procedures.
Analytical Process
1. Total Respirable Dust (TRD). Filters are conditioned and weighed to determine the mass of respirable dust collected. TRD is calculated from the net mass gain and the total sampled air volume.
2. Respirable Combustible Dust (RCD). To quantify the combustible fraction, the loaded filter is heated to approximately 400°C under controlled conditions. This step removes carbonaceous material, including diesel particulate. The remaining mineral residue is weighed, and the RCD value is calculated by subtracting the mineral fraction from the previously measured TRD.
3. Optional Crystalline Silica Analysis. The mineral fraction can be further analyzed for Quartz and Cristobalite providing additional insight into respirable hazards present in the workplace.
Advantages of the LCS RCD Method
- Regulatory relevance: Aligns with Canadian mining guidelines that rely on RCD as a surrogate for diesel particulate exposure.
- Cost‑effective: Uses PVC filters instead of sintered silica membranes, reducing overall service costs.
- Multiple results from one sample: TRD, RCD, and optional Crystalline Silica can be obtained from a single filter.
- Improved exposure insight: Differentiates between combustible and mineral dust fractions, supporting better control strategies and indoor air quality assessments.
- Defensible methodology: Built on recognized NIOSH and ASTM procedures, suitable for regulatory reporting and occupational hygiene programs.
Requesting RCD Testing
LCS Laboratory works with industrial hygienists, safety professionals, and mining operators across Canada and internationally. To request Respirable Combustible Dust (RCD) testing or to discuss sampling strategies, reporting options, or program design, please contact us by email.
