Unlike other bulk samples that are friable and easier to analyze by normal methods, vinyl floor tile is considered nonfriable. Therefore, specific procedures must be performed to expose any fibrous substances that may be contained in the floor tile sample. The following information details the procedures involved in analyzing floor tile for asbestos content.

Routine Procedure

Tile is analyzed under a stereomicroscope. If any suspect fibers are present, they can be analyzed by Polarized Light Microscopy (PLM). Once proper identification of suspect fibers has been determined by PLM, the percentage of asbestos present in the sample is established.

Percent of asbestos in the tile is made by Calibrated Visual Area Estimation per sample layer. Analysts are trained on these samples regularly, both in-house and through participation in the National Voluntary Laboratory Accreditation Program (NVLAP), to assure that the proper estimation of substances is an acceptable range and quality control/quality assurance levels remain consistent.

Point Counting Method

If routine PLM analysis finds the sample to be nonasbestos-containing material or containing asbestos in low concentration levels, the tile can be analyzed by an alternative method known as point counting. Point counting is used to more accurately determine the amount of asbestos present by removing some of the interferences (i.e. binder, carbonate minerals, etc.) that may hinder the analyst's ability to determine the amount of asbestos present.

While point counting can find a greater number of smaller fibers than routine PLM analysis, the process does not detect very small fibers that can be contained in the tile. If this situation arises, the sample can then be analyzed by Transmission Electron Microscopy (TEM) or by Scanning Electron Microscopy (SEM).

Method Comparisons

Although analysis by TEM would provide the most accurate results, it is not recommended for routine testing by the Environmental Protection Agency (EPA) due to its cost. Bulk analysis by TEM should only be used in extreme cases, i.e. legal disputes.

Point counting is also highly effective for analysis of floor tile, but is usually unnecessary unless a sample has been found to contain asbestos in amounts between <1% to 10% and the renovation or demolition activity requires a permit from the National Emission Standard for Hazardous Air Pollutants (NESHAPS).

In order to simplify procedures involving PLM analysis of the tile, the EPA and NVLAP suggest the following operating steps when analyzing bulk samples for asbestos content:

1. If PLM analysis indicates that no asbestos is detected, point counting would not be necessary.

2. If the material layer(s) can not be proven to be asbestos-containing by at least one percent (1%), the material will either:

a. be considered and reported as either nonasbestos-containing material or trace.
b. resampled and analyzed per client request.
c. prepared and analyzed per Point Count Method (either by Polarized Light Microscopy and/or Transmission Electron Microscopy) per client request.

3. If the sample result contains asbestos in amounts between <1% and 10% and renovation or demolition is to occur in the sampled area where a NESHAPS permit is required, point counting must be conducted if you wish to prove the material is non-asbestos.