Asbestos Inspections & Surveys



This section covers all aspects of collecting bulk samples of suspect materials.  Included are procedures for planning, collection and documentation of samples, as well as quality assurance procedures and overview of the analytical methods used for bulk sample analysis.  New York State requires that any individual who collects bulk samples must have the training and certification of a Building Inspector.


Each space, including hallways, closets, attics, steam tunnels, trenches and pipe chases, must be considered in planning a building inspection/sampling project.  Inspect walls, ceiling, beams, ductwork, flooring and any other surfaces.  Asbestos containing materials are often found in areas considered inaccessible, for example, behind walls and above ceilings.  Sampling of materials in these areas requires the cooperation of the building owner and may involve the use of destructive sampling techniques.  It may be necessary to remove cinderblock, climb along beams and rafters, cut holes in plaster or wallboard, remove carpeting and false flooring, etc.

In determining homogeneous areas, if there is any reason to suspect that materials might be different, even though they appear uniform, treat them separately.  For example, material in different wings of a building, on different floors, or in special areas such as cafeterias, electrical rooms, machine shops, boiler rooms, etc., should be treated as separate sampling areas unless there is good reason to believe that the materials are identical.

In a large, multi-story building, a separate sampling area for each floor may not be necessary.  If the materials appear identical on every floor; several floors can be grouped into one sampling area.  Do not group floors if it is known that the material was applied at different times, or if selection of homogeneous sampling areas is a subjective process.  When in doubt, assign materials to separate sampling areas.



The person performing bulk sampling will need to have a variety of equipment to successfully and safely accomplish the collection of bulk samples.  A basic selection of sampling equipment should be assembled in kit form for routine sampling projects.  Other equipment or supplies may be needed based on particular inspections and for certain types of suspect materials.

Basic Sampling Kit

  • Bulk sample containers should be hard plastic containers with secure, airtight lids. Zipper-locking plastic bags (freezer type) may be used.
  • Extension ladder (folding type is ideal).
  • Flashlights (a variety of size candle power may be appropriate).
  • Respirator (half-face w/HEPA filters is usually adequate).
  • Plastic drop cloth.
  • Spray bottle with amended water.
  • Utility knife, hammer, pliers, screwdriver, putty knife, pry bar & chisel.
  • Caulk gun and tubes of caulk compound, roofing tar and construction adhesive.
  • Duct tape.
  • Pre-moistened wipes.
  • Marking pen, highlighters & ballpoint pens.
  • Tape measure (25’ and 100’).
  • Core sampler
  • Disposable surgical gloves.
  • Work gloves.


Pre-planning the inspection will result in an organized and efficient inspection.  When the inspector enters the building, he/she should have all equipment ready for use along with copies of building diagrams and chain-of-custody forms.

The inspector should proceed to each homogeneous area in turn, following a logical sequence of sampling.  This will prevent missing samples and avoid conducting follow-up inspections.

A homogeneous area is considered not to contain ACM only if the results of all samples required to be collected from the area show asbestos in amounts of 1% or less. A homogeneous area shall be determined to contain ACM based on finding the results of at least one sample collected from the area shows that asbestos is present in amounts greater than 1%.

The process of bulk sample collection requires a number of steps, as follows:

  • Fit check and put on respiratory protection and disposable coveralls and gloves, if necessary.
  • Only those persons directly involved in the sampling process should be present during sampling.
  • When feasible, all sampling should be conducted when the area is not occupied.
  • Place a plastic drop cloth on the floor below the surface to be sampled.
  • Set up a ladder or other equipment as needed.
  • Attach a label to each sample container with the location ID, any homogeneous area number, and description of the material sampled.  Be sure to carefully document the sample to avoid confusion in the laboratory or any question about the validity of the inspection.
  • Spray the area to be sampled with amended water.  Carefully collect the sample.  Be sure to penetrate any paint or protective coating and all layers of the material to be sampled.
  • Place the sample in the pre-marked container, and tightly seal it.  Wipe the outer surface of the container to avoid any cross contamination.  The use of small containers such as 35mm film canisters is recommended.  Avoid using containers, which might break, tear, or lose their lid easily.  Containers must be airtight.
  • Complete the chain-of-custody form.  Be sure that every sample is listed on it.


Depending on the type of survey being performed, it may be necessary to repair sample sites such that the material does not release fibers, present a hazard (damaged wallboard) or leave an unsightly appearance.  Roof sample sites must be repaired even if only as a temporary measure to prevent water damage.  The extent of repairs required must be determined with the client prior to the start of sampling. Repair of sampling sites may include the following:

  • Filling in the hole where the sample was collected with caulking compound and/or acrylic adhesive to seal the site and avoid any release of fibers.
  • Filling in roof sample sites with tar or roof flashing compound.
  • Where carpet or cove molding have been disturbed, using all purpose construction adhesive to re-attach the disturbed material.
  • Cleaning your tools and wet wiping and/or HEPA vacuuming the area to remove all debris and contamination.



Nine samples per homogeneous sampling area are recommended.  With nine samples, the likelihood of detecting asbestos when it is present is very high.  Cost or other constraints may limit the number of samples that can be collected.  If nine samples will not be collected, use the following guide to determine the minimum number as required by AHERA.  This number depends on the type of suspect homogeneous area and the amount of the material.

Surfacing Material

  • Collect at least three randomly distributed samples from each homogeneous area that is 1000 ft² or less.
  • Collect at least five randomly distributed samples from each homogeneous area that is greater than 1000 ft² but less than or equal to 5000 ft².
  • Collect at least seven randomly distributed samples from each homogeneous area that is greater than 5000 ft².


Thermal System Insulation

  • Collect at least three randomly distributed samples from each homogeneous area of thermal system insulation.
  • Collect at least one sample from each homogeneous area of patched thermal system insulation if the patched section is less than 6 linear feet or 6 ft².
  • Collect at least two randomly distributed samples from each insulated mechanical system (including fiberglass insulated) where cement is used on tees, elbows or valves.
  • Samples are not required from any homogeneous area where you have determined that all insulation is fiberglass, foam glass, rubber, or other non-asbestos containing materials.  In making this determination, it is critical to examine all layers of material, which may be present.

Other Miscellaneous Material

  • Collect at least two randomly distributed samples from each homogeneous area of other miscellaneous material.

In this sampling scheme, sample locations are selected so that they are representative of the sampling area.  When nine samples are collected, they are distributed evenly throughout the sampling area.  If fewer than nine samples are collected, a random sampling scheme is used to determine their location.  Choosing sample locations according to personal judgment produces samples which may not be representative and can lead to wrong decision about the presence or absence of asbestos.  The sampling scheme described here avoids this problem and controls the frequency of mistakes.

Divide the sampling area into nine equally sized sub-areas.  This is done by dividing the length and breadth of the sampling area into three equal lengths and drawing a grid over the diagram (see Figures 19-1 & 19-2 below).  This can be done carefully by eye and exact measurements are not necessary.

If sampling areas do not easily fit into a rectangular shape, parts of the grid might not be in the sampling area.  This is not a problem in most cases.  If, however, a large part of the area is L-shaped, it is advisable to divide the sampling area into two or more separate sampling areas, each of which is approximately rectangular.  Then, select sample locations by applying the sampling scheme to each sampling area.

   FIGURE 18-1                                                         FIGURE 18-2







Sampling Area Diagrams



Example of a Y-Shaped Sampling Area

 For greatest coverage, one sample form each of the nine regions should be collected.  If fewer samples are to be collected, the random number table below (Table 19-1) shows which sub-areas to collect samples in order to follow a random sampling scheme.  For the first area you intend to sample, number the nine sub-areas as shown for Sampling Area #1 on these diagrams.  If three samples are needed, take them from the center of the sub-areas marked 1,2,3, and so on.  Take samples from approximately the center of the sub-area or as close as possible to the center if accessibility, presence of light fixtures, etc., make the center location impractical.  If a sub-area is specified that falls entirely outside the sampling area, take the third sample from sub-area 4.

For very irregular shaped areas, the sampling area may be divided into nine sub-areas of approximately equal size that do not necessarily form a rectangular grid.  The random number table will then need to be adapted to the specific situation.  Figure 19-3 shows an example of a Y-shaped sampling area that was divided into nine sub-areas of equal size.  The first random number table was adapted accordingly to number the sub-areas.  When adapting sampling diagrams, retain the order of the numbered sub-areas from left to right and top to bottom whenever possible.

For each sampling area, use a new random number table.  If you have more than 18 sampling areas, start again at the first random number table to determine sampling locations for Sampling Area 19.


TABLE 18-1









Assign a sample ID number to each sample location.  This ID number will be on the sampling container when it goes to the laboratory for analysis.  Record the ID number and the sample location on the Sampling Area Diagram and also on a data sheet.  This must be done carefully so that there is no uncertainty about the location and identity of each sample.  Make sure that no two samples have the same ID number.  Unique non-systematic numbers may be used to prevent the laboratories from knowing which samples come from the same sampling areas or the same building.  This “blind” procedure helps prevent bias on the part of the analyst since there is no temptation to assume that the next sample will be similar to the previous one.  Alternately, sequential sample numbers can be used, based on date, project number, building number, floor number, or some other scheme.  The method used is entirely up to the inspector, but care should be taken to prevent another inspector from the same firm, using the same system, on the same or different project and submitting identical sample numbers to the laboratory.  This could lead to confusion on the part of the laboratory or the inspection firm.

The sampling procedure is illustrated by this example.  A school was visually inspected for friable materials.  The activity Center Annex was found to contain friable ceiling materials.  All materials were believed to be the same, and; thus comprise one sampling area.

There were not enough funds for nine samples to be collected in every sampling area.  Therefore, the minimum number, based on area, was calculated.  The total area of friable materials is 10,000 square feet, as calculated by:

Area = (60’ x 90’) + (12 ’x 90’) + (60’ x 60’) = 10,000 sq. ft.

 Since this area is greater than 5000 square feet, seven samples should be collected.  This number was from the list appearing earlier in this section.

The sampling area diagram was divided into nine sub-areas.  Assuming this is the second sampling area to be sampled, the second random number table is used.  The region marked “6” in diagram #2 does not fall within the sampling area.  Therefore, the regions marked 1-5 and 7 and 8 were used to obtain seven locations and were marked on the sampling area diagram as shown in diagram #2.  Each sampling location was assigned a unique, non-systematic sample ID number and this number was marked in the sampling area diagram.  A quality control sample was also collected in Region 4 immediately adjacent to the original sample.  This sample was also given a unique, non-systematic sample ID number.


Thermal System Insulation

The concept of homogeneous sampling areas applies equally well to thermal system insulation as to surfacing material.  The major difference is that insulation on thermal systems is likely to be much more varied than materials on surfaces.  A typical building may contain multiple insulated pipe runs from any combination of the following major categories:

  • Hot water supply and/or return.
  • Cold water supply.
  • Chilled water supply.
  • Steam supply and/or return (watch for different pressure steam lines).
  • Roof or system drains.
  • Chemical or waste transport lines.

Each of these systems may have been installed at different times and insulated with different materials. Therefore, it is best to first identify the building system in question and use this information in conjunction with the physical appearance of the insulation to delineate homogeneous sampling areas.

Each “system” may be composed of a variety of materials. For example, the following list contains ten different types of thermal insulation:

  • Corrugated cardboard-type wrap.
  • White chalky pipe lag.
  • Fibrous glass insulation covering a pipe wrap of unknown characteristics.
  • Cementitious “mud” around pipe fittings.
  • Hard, canvas-wrapped insulation of pipe elbows and fittings.
  • Black insulation on boilers.
  • White batt insulation on boiler breeching.
  • Black batt insulation inside ducts.
  • Rope around pipe sleeves in ceiling and floor slabs.
  • Black asphaltic wrap around pipefittings.

Each of these insulation types should be considered a separate component of the system, and a separate homogeneous area for sampling purposes. Fibrous glass, foam glass, rubber, and Styrofoam are not suspect materials. Note that they may cover up ACM or be coated with ACM.

The number of samples and the sample locations will depend on local circumstances. Try to take at least three samples in each sampling area. For long pipe runs or risers, more samples should be taken, especially if the piping extends to more than one functional area.  Pay special attention to any change in the appearance of the insulation on long pipe runs. This would indicate a possible change in insulation type and the need to delineate a new sampling area. Often, insulation will be found to have been replaced with non-ACM below the 6 to 8 foot level due to contact damage, however, above ceilings or under raised floors, the original material may remain.

The AHERA Rule requires at least three random samples for thermal system insulation. Exceptions are:

  • Small (less than six linear or square feet) amounts of patched insulation (at least one sample).
  • Areas of insulating cement (the number of samples to be determined by the Building Inspector).

Normally, samples should be collected at locations where minimal damage will be inflicted on the insulation. Choose exposed ends, damaged areas, or areas where the protective covering or jacket is missing. This is called “convenience sampling”. The AHERA Rule, however, requires random sampling. Thus, samples will have to be taken from intact insulation in most cases. Often, some combination of convenience and random sampling will be employed. Of course, the Building Owner always has the option of assuming the insulation contains asbestos instead of sampling and analyzing for it.

Miscellaneous Materials

Miscellaneous suspect materials are, for the most part, non-friable (ceiling tiles are an exception). As such, sampling is more difficult and destructive methods are often necessary. EPA does not recommend sampling these materials merely to inventory ACM. Instead, they should be identified as suspect (PACM under OSHA requirements) and documented as such in permanent records. For demolition or renovation work, these materials must be sampled or treated as ACM.

Some building owners wish to have miscellaneous materials sampled and analyzed as part of a facility survey. Ceiling and floor tiles are probably the most frequently sampled of materials in the miscellaneous category. If sampling is to be performed, try to identify separate homogeneous areas just as you would for surfacing materials and thermal system insulation. You will probably find that many types, colors, and vintages of floor tile, sheet goods and ceiling tile can be found in a building. In addition, more than one layer of floor covering material may be present. Each layer and associated mastic layer must be considered separately.

For these types of materials, it is often necessary to take “convenience samples” in inconspicuous locations. Care should be taken not to leave visible damage or safety hazards as a consequence of sampling. Ceiling tile samples can often be found as loose pieces of tile above ceilings or a small section of the edge, which will be hidden by the ceiling track. Flooring materials may be sampled under radiators, behind cove molding, under carpet, and in utility closets. Very hard materials such as Transite wallboard or ceiling tile should not be sampled unless an edge can be accessed. These materials can usually be identified as Transite type materials without needless sampling.



Personal Protective Equipment

Since inhalation of asbestos fibers during hundreds of inspection and sampling projects may pose a serious health hazard, the use of personal protective equipment by Building Inspectors is crucial during the sampling process. As a minimum level of protection, Inspectors should wear a half-face type respirator equipped with HEPA filter cartridges. Full-face respirators may also be worn to prevent eye irritation from dust, fibers and debris released during the sampling operation. Full-face respirators, however, may reduce field and range of vision. Disposable coveralls should be worn during sampling if the sampling operation is likely to dislodge pieces of suspect material or if the environment is extremely dusty, such as in a crawl space or dirty mechanical room. Other hazards may also be present such as chemicals, high temperatures, sharp objects, low clearances, etc. These must all be addressed when selecting the appropriate personal protective equipment, including hard hats, gloves, hearing protection and safety shoes. In certain cases, such as confined spaces, atmospheric monitoring instruments may be necessary to test for other atmospheric hazards. In these cases, a safety professional must be consulted to assure that the inspection team is properly trained and equipped to deal with the actual or potential hazards to be faced.

Other Supplies

Inspectors should have plastic waste bags and appropriate labels to handle the disposal of contaminated respirator cartridges, protective clothing, wet paper towels and debris generated during the survey. This material should not be disposed of at the survey site, unless provisions for asbestos waste handling are present. Typically, these waste materials are held pending analytical results, or are assumed to be asbestos contaminated and disposed of as asbestos containing waste. The tools and equipment necessary for the sampling project should be carried in a toolbox or tool belt. A comprehensive list of sampling equipment is provided elsewhere in this section.

Preparing a Diagram

For each sampling area, prepare a diagram approximately to scale, showing the location of each sample. Use of graph paper will greatly assist in producing a quality diagram. The diagram should include the following information:

  • Name and address of the building.
  • Description of sampling area.
  • Approximate area dimensions and/or scale.
  • Name of Inspector and date of inspection.
  • Name of person preparing the diagram and date prepared.
  • Approximate quantities of each suspect material.
  • Locations of each sample collected and sample ID number.

Frequently, a floor plan or detailed building plan will be available. Where such is the case, sample information can be plotted directly onto these scale diagrams.

Quality Assurance

Quality assurance (QA) procedures are employed to ensure reliable results for analysis of bulk samples. The first step is to choose a laboratory that is competent and dependable. Laboratories should be chosen from the list of laboratories participating in the NIST/NVLAP quality assurance program. This is the most rigorous accreditation program for asbestos laboratories in the United States. The List is frequently updated. To obtain the most recent list, call: (800) 334-8571. It’s important to note that all bulk samples collected in New York State must be analyzed at a New York State Department of Health Environmental Laboratory Approval Program (ELAP) accredited lab, and furthermore if the samples are collected within a school regulated under AHERA then the lab must be additionally accredited by NIST/NVLAP.

The second step in a QA program is to monitor the performance of the laboratory where samples are being analyzed. The EPA recommends that for every 20th bulk sample that is collected, a QA sample should be collected immediately adjacent to the 20th sample. Thus the 20th and 21st samples for every group of 20 are side-by-side samples. Laboratory analysis of these two samples is expected to closely agree. Each sample is labeled independently so that the identity of the QA samples cannot be determined except by reference to records kept by the Building Inspector.

QA samples can be handled in one of two ways:

  1. They can be sent together with all the samples to a single laboratory for analysis.
  1. They can be sent to a second laboratory and analyzed independently.

The first method checks on analytical variability within the same lab. The second method checks on variability between labs. Using the second method is most appropriate for large studies.  Laboratory results on QA samples should not disagree on the presence or absence of asbestos (i.e., less than 1% vs. 1% or greater of asbestos).  If significant disagreement occurs, additional samples should be collected and analyzed.

There may also be discrepancies in estimating the exact percentage of asbestos in side-by-side samples. These discrepancies are not as serious as the presence/absence result since any sample of suspect material, which contains more than 1% asbestos, is designated as ACM. However, the comparison of the asbestos percentage estimated by the testing laboratory can provide useful information on the reliability of the analysis. Discrepancies may occur as a result of sample contamination, inconsistent procedures, differences in technique, or mistakes such as the mislabeling of samples. Of course, some variability in the “true” asbestos content of ACM would be expected from one location to the next. Ordinarily the percentage for each QA sample compared with the percentage for its corresponding regular sample should not vary by more than ten percent (10%).

Any disagreement about the type of asbestos mineral (chrysotile, amosite, crocidolite) present should be resolved by additional analysis. Information on mineral type may be important when evaluating alternative methods of managing ACM, especially if removal of the ACM is under consideration. Procedures to ensure the integrity of the samples are also a component of the QA program. Strict chain-of-custody procedures should be followed.

Concluding the Inspection

At the conclusion of the inspection, review all maps and drawings to confirm that sampling of all planned areas has been accomplished. Place all rags, wet wipes, protective clothing and other contaminated disposable materials in a labeled plastic bag. These materials must be properly disposed of as asbestos waste materials or held pending laboratory analysis of samples.

Check all sample containers to be sure that the labels contain all necessary information and that they are securely fastened. Double bag samples for transportation. Samples which must be shipped should be carefully protected with packing material (such as bubble pack). Maintain the original chain-of-custody form for your files and future reference.



Polarized Light Microscopy (PLM) is the EPA approved method for analyzing bulk materials for asbestos. This method of analysis is relatively inexpensive (approximately $15-30). PLM utilizes a light microscope equipped with a polarizing filter. The identification of asbestos fiber bundles is determined by the unique optical and crystallographic properties displayed when the sample is treated with various dispersion staining liquids. These properties (refractive indices, birefringence, sign of elongation and extinction angle) are characteristically unique to each asbestos form and, therefore, can be used to identify the specific asbestos type(s) present in the samples. Identification is substantiated by the actual structure of the fiber and the effect of polarized light in the fiber, all of which is viewed by the trained laboratory analyst. The limit of detection of asbestos by PLM is about one percent (1%) by area. Samples containing lower levels of asbestos are not reliably detected by this technique.

X-ray Diffraction (XRD) is another method used for analyzing bulk materials for asbestos. It is sometimes utilized to confirm the presence of asbestos in a sample already analyzed by PLM if the identity of the fibers remains ambiguous. XRD is not used routinely since it is not as sensitive as PLM in detecting asbestos; its limit of sensitivity is approximately three percent (3%).

Transmission Electron Microscopy (TEM) is often used to confirm the presence or absence of asbestos in non-friable bulk samples following negative or inconclusive results by PLM. Electron microscopy is capable of detecting smaller fibers of asbestos, such as those found in fine dusts and highly milled asbestos. Unless a material is assumed to be ACM the New York State Department of Health (NYSDOH) requires TEM confirmation of suspect non-friable materials which are found to be negative by PLM as described below. TEM analysis cost range from $65 to $100 per sample.

Non Friable, Organically Bound Materials (NOBS)

In New York State, non-friable, organically bound materials must be analyzed by TEM if they are found to be non-asbestos containing (1% or less asbestos). The New York State Department of Health has determined that PLM is not consistently reliable in detecting asbestos fibers in non-friable organically bound materials (floor tiles, mastics, roofing materials, etc.). New York State DOH accredited laboratories are required to report that a confirmation test using quantitative Transmission Electron Microscopy must be conducted prior to treating such non-friable, organically bound materials as non-asbestos containing.

Non-friable, organically bound materials must first be prepared using the gravimetric matrix reduction method. This procedure is the preliminary sample preparation for methods 198.1 (PLM) and 198.4 (TEM).

A small, representative portion of the NOB sample is weighed and ashed in a muffle furnace for I to 12 hours (the average time is about 3 hours). This process removes the organic binder material. The sample is then cooled in a dessicator and reweighed. If the remaining material weight is 1% or less than the original weight, the material is non-asbestos, by definition. If, on the other hand, the remaining weight is greater than 1% of the original weight, the next step is acid reduction of the remaining material. This step removes many interfering minerals, which may remain, while leaving the asbestos unaffected. This step is followed by filtration through a 0.4 µm pore polycarbonate filter membrane, using a vacuum filtration technique. The filter is dried on a hot plate, cooled and re-weighed. If the remaining residue is 1% or less, by definition, the material is non-asbestos. If the remaining weight is greater than 1% of the original sub-sample weight, it is again analyzed by PLM.

When asbestos is present, the weights previously recorded are used to calculate the percent of asbestos in the original sample. If no asbestos is detected, the sample should be analyzed by TEM, or treated as asbestos containing material. However, as previously stated, if the residue is 1% or less than the original sample weight, no further analysis is needed. Anything 1% or less by weight, by definition, is considered non-ACM, even if all remaining residue is asbestos. The flow chart below (figure 19-4) illustrates the process.








Figure 18-4 Gravimetric Matrix Reduction Method Flow Chart


A competent analytical laboratory with the accreditation of the National Institute of Standards and Technology (NIST), should provide a detailed bulk sample analysis report that includes the following information, at a minimum:

  • Client sample identification number.
  • Laboratory sample identification number.
  • Analytical method used.
  • Laboratory quality control procedures.
  • Physical description of sample, as received.
  • Type(s) and estimated percentage of asbestos found.
  • Type(s) and estimated percentage of non-asbestos fibers found.
  • Type(s), if known, and percentage of other components.
  • Date of analysis.
  • Analyst’s signature.
  • Laboratory accreditation number.

This information, along with the data generated in the field (location of sample, type of material, photo references, etc.), should be maintained as part of an overall building inspection record-keeping program.

Sample analysis must be performed by an accredited laboratory for the analysis of asbestos as bulk material. Acceptable accreditations include:

  • National Institute for Standards and Technology (NIST), National Voluntary
    Laboratory Approval Program (NVLAP).
  • American Industrial Hygiene Association (AIHA).
  • New York State Environmental Laboratory Approval Program (ELAP).
  • Other State Laboratory Approvals.

In New York State, laboratories used for asbestos project bulk sample analysis must be NYSDOH-ELAP or AIHA accredited at minimum. For AHERA inspection projects in New York State, NIST NVLAP accreditation is required, in addition to NYSDOH-ELAP.

For inspections performed to comply with the OSHA Asbestos Standard, laboratories must be either NVLAP or AIHA accredited (New York State ELAP accreditation alone is not sufficient).

The method used for bulk sample analysis is EPA 600/R-93/11.6 as established by the Environmental Protection Agency and approved by the New York State Environmental Laboratory Approval Program (ELAP 198.1) using Polarized Light Microscopy (PLM), coupled with dispersion staining.

Recently, The Environmental Protection Agency published supplementary guidance on bulk sample collection and analysis. This guidance addresses the use of the final EPA analytical method referenced above, rather than the “interim method”, and also specifies the procedures to be followed by the both the Inspector and Laboratory for dealing with multi-layer materials, skim coats and wall board joint compound.


September 30, 1994

Supplementary Guidance on Bulk Sample Collection and Analysis

U.S. EPA, OPPT/CMD (7404)

I.   Introduction


Recent Notices in the Federal Register (59 FR 542, Jan. 5, 1994; and (59 FR 38970, Aug. 1, 1994), announced clarifications regarding the analysis of bulk samples obtained from multi-layered systems to determine the presence of asbestos.   As part of a public outreach effort, the Environmental Protection Agency (EPA) developed this supplemental guidance bulletin.  The public should take note that the contents are presented as guidance.   This guidance does not change current regulatory requirements of the 1987 Asbestos in Schools Rule (AHERA).   Local education agencies (LEAs) may choose to adopt the recommended guidance as a matter of policy offering added precaution and protection for workers and building occupants, and also to avoid the possibility of non-compliance with EPA’s National Emission Standards for Hazardous Air Pollutants (NESHAP) regulations.

This bulletin was developed by EPA primarily for two reasons:

1)               To provide guidance regarding the adoption and use of an improved method for the analysis of asbestos in bulk samples (“Test Method  — Method for the Determination of Asbestos in Bulk Building Materials,” EPA/6OO/R-93/116, July 1993).  The improved method is especially useful for detecting the presence of asbestos in asbestos-containing floor tiles, but it also provides better analytical results in building materials that may contain asbestos at low concentrations.

2)       To clarify EPA’s guidance and requirements for the collection and analysis of bulk samples of multi-layered materials, particularly in schools.  EPA recommends that multi-layered samples that have been found to be non-asbestos-containing for the EPA “Asbestos in Schools Rule” (AHERA) be re-sampled before disturbing them, unless lab reports are available documenting that all layers were previously sampled and analyzed. Re-sampling (if elected) should be done according to the guidelines set forth previously in a January 5, 1994 NESHAP Federal Register Notice, an Aug. 1, 1994 AHERA Federal Register Notice, and in the improved analytical method to avoid potential violation of the asbestos NESHAP regulations.

Note that under the AHERA and NESHAP regulations, LEAs can assume that certain materials are asbestos containing and manage them as such. This continues to be an acceptable alternative to sampling or re-sampling.

Both EPA’s AHERA program for schools and the EPA asbestos NESHAP program recommend the adoption of the improved bulk sample analysis method published by EPA’s Office of Research and Development in July 1993 (EPA/6OO/R-93/116).  EPA developed the improved analytical method to address certain materials:

  • That are known to contain asbestos fibers, but in which the asbestos percentage is “low” (<10%)
  • Where the presence of asbestos is obscured by a matrix binder of some kind (e.g., vinyl or asphalt floor tiles)
  • In which small, thin fibers are present, but are frequently not detected at the magnification and resolution limits of polarizing light microscopes.

The improved method builds on the previous (1982) “Interim” polarizing light microscope (PLM) method.    As before, it begins with a careful examination of the sample using a stereo-microscope, then proceeds (as before) to the examination (if sample specimens under a polarizing light microscope.    In most cases, these steps will be sufficient to characterize a sample as asbestos containing (asbestos present   > I %) or non-asbestos-containing (no asbestos detected, or 1 % or less in the sample).

The improved method includes additional procedures required for the reliable analysis of certain bulk building materials, such as steps for the elimination of the obscuring matrix materials (quantitative analysis of the sample is improved by the use of comparative standard samples having known quantities of asbestos matrix materials), as well as specifying use of transmission electron microscopy (TEM).   These additional steps comprise the chief improvements in the new method.   The Agency believes that adoption of the improved method should remedy the analytical problems frequently encountered when testing materials such as resilient floor tile (vinyl or asphalt), mastic, and “layered” building materials using the 1982 “Interim” PLM method.

Finally, the results obtained from following recent guidance on “layered samples” and use of the improved sampling procedures for certain problem materials should, where it is possible to do so, facilitate following EPA’s “manage in place” guidance for asbestos operations and maintenance (O&M) programs, (EPA •Green Book,” July 1990).

II. Issues of Concern

 There are two principal issues addressed in this guidance.

Issue 1.  The possible misidentification of certain “problem” materials as non-asbestos containing, with subsequent failure to include them under a surveillance and O&M program.   These “problem materials” include asbestos-containing floor tiles, and certain multi-layered building materials.

The 1982 EPA “Interim Method for the Determination of Asbestos in Bulk Insulation Samples” (40 CFR 763, Appendix A to Subpart F) was limited in that it did not provide guidance for analyzing materials that contain thin (i.e., <0.25 micrometer) asbestos fibers.   As a consequence, floor tiles analyzed according to the 1982 method and for which negative results were reported may actually contain undetected asbestos in the form of thin fibers below the limits of resolution of the polarized light microscope.

The improved method provides acceptable procedures for reducing matrix materials so that fibers may be made available for microscopic analysis.  It also addresses the thin fiber limitation of the 1982 method by providing directions for the use of transmission electron microscopy (TEM) as needed.

The improved method also directs laboratories to analyze the individual layers or strata of a multi-layered sample and to report a single result for each layer.   The 1982 “Interim Method,” in contrast, provided that the analytical result for a multi-layered sample with discrete layers be reported as one result across all layers.   (Although the analyst was directed to identify the presence of discrete layers as seen under stereo-microscopic examination of the bulk sample, and to identify and quantify asbestos fiber content in each layer.) Because the 1982 method allowed the result to be reported as one number, multi-layered samples, which may have contained asbestos in a single layer, may have been reported by laboratories as non-asbestos-containing.

Thus, under the recommended improved test method, more than one result will be reported for multi-layered samples, and a multi-layered sample which previously was determined to be non-asbestos-containing may actually have layers which will be classified as asbestos-containing based on the presence of asbestos in greater than one percent.   The January 5, 1994 NESHAP notice in the Federal Register directs the attention of the regulated community to their requirement to analyze multi-layered samples in this manner for compliance with NESHAP.

The recognition, sampling, and analysis of “layered” building materials may be of particular importance when known or assumed asbestos-containing building materials (ACBM) are left in place.    AHERA requires the management of known or assumed ACBM under a school’s asbestos operations and maintenance program.    EPA issued guidance in July 1990 (“Managing Asbestos in Place,” the “green book”) that recommends similar programs in any building or facility where asbestos-containing materials (ACM) are present.

For example, if a planned renovation or remodeling is scheduled, and if the outer surface (i.e., the surface exposed to the room’s interior) of a wall or ceiling system is an asbestos-containing layer, that fact should be known prior to some disturbance such as sanding in preparation for painting.   Similarly, if an underlying layer of a wall or ceiling system is going to be disturbed (e.g., making a penetration to install light fixtures or heating/cooling ducts), that fact should be known before a service or maintenance worker cuts or drills into the wall or ceiling, and should affect how that work is performed.   (See the 1992 guidance manual, “Asbestos Operations & Maintenance Work Practices,” published by the National Institute of Building Sciences.)

Issue 2.  Possible (unknowing) violations of the asbestos NESHAP by LEAs.

EPA’s asbestos NESHAP program has also made “applicability determinations” regarding plaster/stucco or skim coat layers applied over wallboard systems.   As stated above, the EPA Asbestos NESHAP position was summarized in a notice of clarification recently published in the Federal Register (January 5, 1994).  That notice in the Federal Register directs the attention of the regulated community to the NESHAP requirement to analyze multi-layered samples and report results for discrete layers.

Schools operating under the requirements of AHERA have been, and continue to be, subject to EPA’s asbestos NESHAP compliance requirements, when involved in renovation or demolition activities where RACM (regulated ACM) will be disturbed.  EPA believes that the August 1994 Federal Register notice clarifies LEA responsibilities under the asbestos NESHAP, and that this guidance regarding the use of the improved sampling and analysis method will further clarify the situation and reduce the potential for possible violations of the asbestos NESHAP.

III. Examples of Materials of Concern

Building materials typically containing thin asbestos fibers (e.g., floor tiles) or asbestos in low concentration (< 10%) are the subject of this guidance. Also, plaster wall or ceiling systems; resilient flooring systems (flooring, mastic, underlayment), and wallboard systems are examples of layered building materials subject to this guidance.

EPA does not regard a sheet of “plasterboard” by itself (“sheetrock.” “wallboard,” “gypsum board”) as a multi-layered material.   EPA is not adding a requirement to sample a section of plasterboard as such (see definition in APPENDIX) as a “layered” material under either AHERA or NESHAP regulations.

Lack of knowledge about the possible asbestos content of different strata in layered materials can lead to increased exposure risk under certain circumstances.   In this guidance bulletin, EPA is attempting to address the concern for sampling layered materials in a manner so as to reduce risk, as well as the need to comply with recent NESHAP interpretations.   The Jan. 5, 1994 Federal Register asbestos NESHAP clarification should be consulted with regard to materials such as joint compound, texturing materials, etc. added to the surface of wallboard, and when those materials would be subject to EPA’s NESHAP regulation.

NOTE:   Section V of this guidance bulletin offers a suggested strategy for distinguishing between joint compound found at joints in wallboard systems or when the material was applied as a skim coat; i.e.. for determining whether  “joint compound” has been applied as a “skim coat” over a wall surface,   (as referred to m the NESHAP Jan. 5, 1994 FR notice)

IV.   Helpful Sampling Techniques

LEA “designated persons,” accredited asbestos Building Inspectors, consultants, and others should follow previous EPA published requirements and guidance with regard to techniques for obtaining bulk samples of building materials in order to analyze them for the presence of asbestos.   This information was presented both in guidance documents (such as the 1985 Pink Book and the Purple Book), and in the 1987 AHERA “Asbestos in Schools” Rule Sec. 763.86, 763.87 (see “References.”)  The techniques are also discussed in approved training courses for accrediting Building Inspectors.

To clarify EPA’s guidance, it is important for the sampling device (core borer, knife, etc.) to penetrate all layers of the sample to the substrate.   As discussed in Section II, it may be important to know whether discrete layers of a multi-layered sample contain asbestos.   Service and maintenance workers may need to perform their work on exposed surface layers that contain asbestos.   Or, their task may require them to penetrate non-asbestos layers into or through underlying asbestos-containing layers.  Knowledge of where asbestos occurs in a multi-layered sample is important as a means of reducing the potential for asbestos exposure, and in selecting proper work practices to do so.   It is also important to know the asbestos content of individual layers, of course, for NESHAP compliance purposes.

Thus, the person who obtains the sample for analysis may need to use professional judgment based on an on-site situation.   If a bulk sample remains intact through all layers, and the inspector judges that the sample will remain intact until it reaches the analytical laboratory, the sample may not need to be separated into its respective layers until the laboratory analyst does so.  However, if a bulk sample crumbles or breaks down at the time of sample collection, the sample collector may be required to take separate samples from discrete layers at the site, and carefully identify them and their position in the multi-layered system for proper and useful reporting by the laboratory.

EPA guidance regarding the need to keep layers separate as a particular sample is collected, therefore, depends on several factors.   They include the professional judgment of the accredited individual who takes the sample, the physical condition and integrity of the material making up discrete layers of a multi-layered sample, the possible importance of reporting asbestos content of an exposed surface layer vs. inner layers of a system (depends on planned activity, such as in O&M tasks), and being in compliance with regulatory requirements.

The 1993 bulk sample guidance bulletin stresses the need for taking sufficient sample volumes of the material to be analyzed.   Sufficient sample volumes differ for different material types.  Since the quantity of the sample can affect the analytical sensitivity, EPA’s recommendations in the July 1993 method should be noted.

V.   Suggested Sampling Strategy for Dealing with Joint Compound vs. a Skim Coat/Add-on Application (NESHAP Compliance Issue:

Sampling needs to be conducted to determine if materials are joint compound or a skim coat application of the compound over a wall surface.)   Be aware that materials applied to ceilings might differ from materials used on walls, and that original construction and later renovations can result in the application of different materials at different times.   Joint compound applied to drywall Installations prior to 1980 is more likely to contain asbestos than with installations after that date.


  1. 1.     JOINT COMPOUND: Sample where joints are expected (take a minimum of 3

samples). For example:

  1. Inside or outside corners
  1. Wallboard joint intervals; i.e., 4 feet from comers on wall stud.   Use stud locator or knock
    on wall to locate stud (listen for “solid* sound).   Look at walls above suspended ceiling panels; unpainted joints covered by joint compound are often discernable there.
  1. Note that joint compound is often applied to fill depressions around nail heads; consider the “spottiness” of that type of application.

2.  ADD-ON MATERIALS: Sample where joints are NOT expected (take a minimum

of 3 samples).   For example:

A.  Between corners and wallboard joint intervals. Locate by knock on wall, listen for “hollow* sound.

3.  KEEP GOOD RECORDS: of sample locations for later evaluation of results.   Note:  A laboratory cannot distinguish joint compound at joints from the same material used as a skim coat.  Therefore, it is very important that individuals collecting samples clearly describe the sample composition so that the analytical laboratory knows whether to report the results as individual layers or as a “composite” result for non-layered material.   (See B-l, B-2 below.)

B.  Analysis of samples en laboratory, and data analysis

by the sampler/assessor

All samples with outer layer having > 1 % asbestos on wallboard will be noted.  When this situation applies, then the following must be considered:

  1. If only joint sampling areas show layers with > 1 % asbestos, then material is joint compound.

a.  Combine (weighted) analytical results into composite result for each


1)             If result is < 1 %, no management is necessary.

2)      If result is > 1 %, the material is RACM (NESHAP) and management is necessary.

2.  If samples from both joint sampling area and non-joint areas show layers with > 1 % asbestos, then the material should be considered “skim coat” or add-on    material.

a. Do not composite (average) the results; report the results for each layer.  Provide a description of each layer in the report, to include their location in relation to each other.

b. Material so located should be treated as separate RACM layers

according to the asbestos NESHAP, and management is necessary.

VI. References

  1. Advisory Regarding Availability of an Improved Bulk Sample Analysis Test Method; Supplementary Information on Bulk Sample Collection and Analysis; 59 FR 38970, Federal Register, Aug.1, 1994.
  1. Asbestos-Containing Materials in Buildings: Simplified Sampling Scheme for Friable Surfacing Materials (pink book), U.S. EPA 560/5-85-030a, October 1985.
  1. Asbestos-Containing Materials m Schools; Final Rule and Notice (AHERA Rule). 40 CFR Part 763. October 1987.
  1. Asbestos NESHAP Clarification Regarding Analysis of Multi-layered Systems, 59 FR 542, Federal Register Jan. 5, 1994.
  1. Guidance for Controlling Asbestos-Containing Materials in Buildings (purple book), U.S. EPA 560/5-85-024, 1985.
  1. Guidance Manual: Asbestos Operations and Maintenance Work Practices, National Institute of Building Sciences (NIBS), Washington, D.C., September 1992.
  1. Managing Asbestos in Place: A Building Owner’s Guide to Operations and Maintenance Programs for Asbestos-Containing Materials (green book), U.S. EPA 20T-2003, My 1990.
  1. National Emission Standards for Hazardous Air Pollutants for Asbestos (Asbestos NESHAP Rule), 40 CFR 61, subpart M, November 1990.
  1. Test Method: Method for the Determination of Asbestos in Bulk Building Materials, U.S. EPA 6OO/R-93/116, July 1993.

APPENDIX:  Definitions

 Binder:             With reference to a bulk sample, a component added for cohesiveness, such as plaster, cement, glue, vinyl, asphalt, etc.

Bulk sample:   For the purposes of this guidance, representative portion of building material taken at one distinct location for qualitative and quantitative identification of asbestos.  In a multilayered system, one needs a representative portion of each layer.

Discrete:         Individually distinct, visually recognizable.

Layer:             Stratum; one thickness of some material laid or lying over or under another thickness of the same or different material.

Material:        The substances or constituents of which something is composed or can be made. Various materials are used in building construction,such as sand, wood, metal, plaster, cement, asbestos, etc.

Matrix:          Material in which asbestos fibers are enclosed or embedded.

NESHAP:     “National Emission Standards for Hazardous Air Pollutants;” EPA’s asbestos NESHAP regulation, at 40 CFR 61 Subpart M (especially for demolition and renovation activities).

Plaster:          A pasty composition comprised largely of water, lime, and sand, that hardens on drying and is used for coating building components such as walls, ceilings,  and partitions.   Asbestos fibers or other fibrous materials sometimes have been mixed into the plaster to give particular properties.

“acoustical” plaster — plaster specially formulated and applied (sprayed or trowelled on) so as to deaden or absorb sound.

“browncoat” plaster — also called “scratch coat;” a base coating of plaster, usually applied over perforated plaster board, wooden lath or wire mesh.

“topcoat” plaster — a surface finish layer of plaster, usually white and smooth; may contain sand to produce a grainy surface.

Plasterboard:   A board used in large sheets as a backing or as a substitute for plaster in walls and consisting of several plies of paper, fiberboard, or felt, usually bonded to a hardened gypsum plaster core. aka; (“gyp(sum] board,” “drywall,” “wallboard,” “sheetrock”)


PLM:           Polarized light microscopy; a technique for analyzing bulk building material samples for presence of asbestos.  The sample is illuminated by polarized light and viewed under an optical microscope.

Sample:            To take a sample of or from some material, especially to judge the quality or composition of that material.

Separable:        Capable of being separated.

Skim coat:        A thin layer or coating of one material (e.g., plaster, stucco, joint compound) applied over another.

Stratum:          Layer;   one of a series of layers, levels, or gradations in an ordered system;  a bed or layer.

Stucco:           A fine plaster used in the decoration and ornamentation of interior walls.  Also, a material usually made of Portland cement, sand, and a small amount of lime, applied to form a hard covering for exterior walls.

Substrate:     The underlying support, foundation, or base (wood lath, wire screen, concrete, etc.) to which something else (e.g., plaster) is applied.

System:         An integrated group of building components which form an organized functional unit, such as a wall system, or ceiling system, or floor system.

TEM:               Transmission Electron Microscopy and related techniques; will enable specific identification of thin asbestos fibers.