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Asbestos PLM Bulk Sampling

Bulk Sampling for PLM analysis

Source: How to Manage Asbestos in School Buildings—EPA 910-B-96-001
Note: While this guide recommends common practices, other requirements might vary by state and/or agency. 


  • To determine whether the suspect material contains asbestos, and if so, at what levels.
  • To determine whether the levels indicate the classification of the material as asbestos containing material.

Sampling Overview

  • Identification of ACBM

    The initial inspection to identify all the ACBM in a building begins with locating and listing all “homogeneous areas” of material that are suspected to contain asbestos. A “homogeneous area” is an area of surfacing material, thermal system insulation, or miscellaneous material that is uniform in color and texture. Suspected ACBM in a homogeneous area or functional space must then be treated as ACBM unless samples are taken and the sample analyses show the material to be non-asbestos. “Functional space” means a room, group of rooms, or homogeneous area designated by a person accredited to prepare management plans, design abatement projects, or conduct response actions.

  • Categories of ACBM

    Interior materials suspected of containing asbestos must be categorized as one of the following three types according to EPA:

    1. Surfacing Materials—Interior ACBM that has been sprayed on, troweled on, or otherwise applied to surfaces (structural members, walls, ceilings, etc.) for acoustical, decorative, fireproofing, or other purposes. This includes acoustical plaster, hard plasters (wall or ceiling), fireproofing insulation, spray-applied or blown-in thermal material, joint or patching compound (wall or ceiling), and textured paints or plasters.
    2. Thermal System Insulation—Insulation used to control heat transfer or prevent condensation on pipes and pipe fittings, boilers, breeching, tanks, ducts, and other parts of hot and cold water systems; heating, ventilation, and air conditioning (HVAC) systems; or other mechanical systems. These insulation materials include pipe lagging, pipe wrap, HVAC duct insulation, block insulation, cements and muds, and a variety of other products such as gaskets and ropes.
    3. Miscellaneous Materials—Other, mostly non-friable products and materials found on structural components, structural members or fixtures, such as floor tile, ceiling tile, construction mastic for floor and ceiling materials, sheet flooring, fire doors, asbestos cement pipe and board, wallboard, acoustical wall tile, and vibration damping cloth. “Miscellaneous materials” do not include thermal system insulation or surfacing materials.

Note: Batt, blanket, and blown-in insulation should be placed in one of the above categories according to use. Once a material is classified as a particular type, the inspector should identify areas where the materials are all of one type. EPA suggests that wings or additions added to a building should not be considered homogeneous with the original structure. Building materials used in different buildings should not be considered homogeneous. If there is any reason to suspect that materials might be different, even if they appear similar, they should be assigned to separate homogeneous areas, and if it is determined that sampling is needed, such materials should be sampled separately. It is important that the inspector correctly identify all homogeneous areas in the inspection report.

  • Determination of ACBM

    Under the AHERA Rule, all material suspected to be ACBM must be assumed to be ACBM unless:

    1. The homogeneous area is sampled, and analyzed and found to be non-asbestos; or,
    2. The suspect or assumed ACBM is in a building built after October 12, 1988, that is certified by an architect or developer as being asbestos-free.
  • Sample Requirements

    The following table shows the number of samples required to be collected from each type of homogeneous area to meet the AHERA regulation requirements.

Bulk Sampling Requirements

Type of Material

Samples Required

Friable Surfacing Material


  • Area ≤ 1,000 sq. ft.


  • Area > 1,000 sq. ft. but ≤ 5,000 sq. ft.


  • Area > 5,000 sq. ft.

Thermal System Insulation (TSI)

  • TSI not assumed to be ACBM
  • Patched TSI not assumed to be ACBM (if patched section < 6 linear or sq. ft.)
  • Each insulated mechanical system not assumed to be ACBM where cement or plaster is used on fittings such as tees, elbows, or valves.
  • Friable Miscellaneous Material not Assumed to Be ACBM
  • Non-friable Suspected ACBM not Assumed to Be ACBM
Sample in a manner sufficient to determine if material is or is not ACBM*

Note: The regulations do not indicate how many samples are required to meet the "in a manner sufficient to determine." But it is recommended that a minimum of three samples be taken from any homogeneous area to prove that a material does not contain asbestos. However, the designation of ACM for a homogeneous area based on one positive bulk sample result is acceptable. It is recommended that all samples taken always be analyzed, since one sample analysis is rarely representative of a homogeneous area.

*EPA recommends that three samples be taken to meet this requirement


  • Physical Assessment

    Once all of the ACBM in a building has been identified, one must perform a physical assessment of all TSI and friable material. The physical assessment of ACBM involves classifying the material into one of the following seven Physical Assessment Categories:

    1. Damaged or significantly damaged thermal system insulation (TSI) ACBM
    2. Damaged friable surfacing ACBM
    3. Significantly damaged friable surfacing ACBM
    4. Damaged or significantly damaged friable miscellaneous ACBM
    5. ACBM with potential for damage
    6. ACBM with potential for significant damage
    7. Any remaining friable ACBM or friable suspected ACBM


    The physical assessment may include the following considerations:

    • Location and amount of the material
    • Condition of the material, specifying:
      • Type of damage or significant damage
      • Severity of damage
      • Extent or spread of damage
    • Whether the material is accessible
    • Material’s potential for disturbance
    • Known or suspected causes of damage or significant damage
    • Preventive measures that might eliminate the reasonable likelihood of undamaged ACBM from becoming significantly damaged.

    Because the physical assessment is used to determine which response actions will be chosen to manage the asbestos, proper identification and assessment of ACBM are vital to the effective implementation.


  • The samples removed should be properly sealed in a sealable bag and appropriately labeled before being shipped to EMLab P&K's asbestos testing laboratory for analysis using polarized light microscopy (PLM).