• Asbestos-Airborne Fiber Count
  • Workplace Exposure


  • PLM Analysis
  • Gravimetric 1,000 and 400 Point Counts
  • Soil Analysis
  • Asbestos Wipes


Asbestos-Airborne Fiber Count

(NIOSH 7400)

PCM analysis is commonly used to measure airborne fibers in ambient and outdoor air particularly prior, during and post asbestos remediation. This method involves a technician setting up a pump that is attached to a cassette to run for a minimum range of 0.5 to 16 L/min in order to collect between 100 to 1300 fiber/mm². The cassettes contain a filter that is then prepared and analyzed by one of our qualified PCM analysts. The analyst uses PCM counting rules that are specified by NIOSH 7400 to count fibers that are present on the filters. The limit of detection (LOD) is dependent on the volume and quantity of fibers counted. The regulatory clearance level is set by the EPA at 0.01 fibers/cc (fibers per cubic centimeter). PCM results do not differentiate between asbestos fibers and non-asbestos fibers. Additionally, fibers less than 0.25 microns in diameter will not be detected using this method.

Workplace Exposure

(NIOSH 7400)

In order to be OSHA compliant, we calculate the Time Weighted Average (TWA) for personal sampling. OSHA requires employers to ensure that no employee is exposed to an airborne concentration of asbestos in excess of 0.1 f/cc of air as an 8-hour time weighted average. Determinations of employee exposure shall be made from breathing zone air samples that are representative of the 8-hour TWA and 30-min short-term exposure of each employee.

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PLM Analysis

[US Federal Register 40 CFR 763, Subpart F, Appendix A, EPA 600/R-93/116, EPA 600/M4-82-020, and OSHA ID-191 (not covered by NVLAP)]

The definition of a Bulk Sample is a small portion of a suspect asbestos containing building material collected for laboratory analysis to determine the asbestos content.

The purpose of bulk sampling is to determine the quantity and type of asbestos that may be present in building materials. This will assist the property owner in making decisions for any remedial actions required and assist in creation of an asbestos management plan. Sampling of materials in buildings can help reduce costs, as the materials will be managed differently if they do not contain asbestos.

A polarized light microscope (PLM) allows analysts to view optical properties of fibrous minerals present in submitted samples. PLM can differentiate asbestos from non-asbestos fibers, classify the 6 different types of asbestos and provide a visual estimate percentage of asbestos and non-asbestos fibers/minerals detected in the sample. Asbestos is most commonly found in acoustic ceiling (popcorn ceiling), floor tiles, linoleum, mastic/adhesives, drywall and joint compound, stucco, plaster, duct insulation, window putty and roofing materials.

Accreditation is provided through the National Voluntary Laboratory Accreditation Program (NVLAP), through participation in Proficiency Analytical Testing (NIST, PAT rounds) and on-site assessments. Additionally, we maintain an extensive Quality Assurance and Quality Control (QA/QC) program to assure that our data is accurate and precise.

Gravimetric 1,000 and 400 Point Counts

(US Federal Register 40 CFR 763, Subpart F, Appendix A, EPA 600/R-93/116, EPA 600/M4-82-020)

When a PLM Bulk sample is found to contain low asbestos concentrations, the sample can be further analyzed using the point count method. This gravimetric technique is applied to more accurately determine the percent of asbestos within the material. This is extremely useful when analyzed samples are reported as <1% or “trace” asbestos. This method requires that a portion of the sample be weighed, ashed and acid treated to remove a variety of matrix materials that obscure asbestos fibers. After recording all the weights, an analyst uses a special ocular graticule for the microscope that contains a superimposed grid of 25 points and counts whether or not asbestos fibers land on each point, either to 1,000 or 400 points. A point count analysis can determine if the sample is truly below 1% and can help eliminate bias due to density and projected area differences. The point count asbestos result supersedes the PLM visual estimation asbestos result. Reporting limits for this method are <0.1% for 1,000 point counts and <0.25% for 400 point counts.

*Non-gravimetric point counts can be requested and performed but we recommend gravimetry for the most precise results.

Soil Analysis

(CA EPA Air Resources Board Method 435, EPA 600/R-93/116)

Quantitative (1,000 or 400 point count)

Contamination in soil may be caused by construction, mine and manufacturing wastes, naturally occurring asbestos (NOA), and other sources. This method requires to dry, crush, homogenize and sieve the submitted soil sample. Once the sample is prepared, a 1,000 or 400 point count is performed to quantify results to <0.1% and <0.25% respectively.

Qualitative (Positive or Negative)

 Soil can be thoroughly analyzed to examine rocks, debris or any other suspicious materials for asbestos or NOA. The results are reported as either positive or negative.

Asbestos Wipes

[US Federal Register 40 CFR 763, Subpart F, Appendix A, EPA 600/R-93/116, EPA 600/M4-82-020, and OSHA ID-191 (not covered by NVLAP)]

Qualitative (Positive or Negative)

 Wipes are typically used to monitor cleanliness (housekeeping) of the working surfaces in the area where asbestos can be present (ex., remediation projects). Wipes work best on flat and glossy surfaces like ceramic tiles, painted panels, steel, and glass. We recommend using a wipe that is free of chemicals such as Ghost Wipes. Once the samples are returned to the laboratory, we ash the wipe and analyze the leftover ash/dust for asbestos fibers. The results are reported as either positive or negative.

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