Sampling Variance for Asbestos-Containing Materials

The EPA (U.S. Environmental Protection Agency) says one thing—OSHA (Occupational Health and Safety Administration) says another. Sampling variance can certainly trip you up when it comes to compliance. So what exactly do you have to consider when it comes time to sample for asbestos?

First, know that both OSHA and U.S. EPA regulations will likely apply to your project. You’ll want to make sure that you satisfy the requirements for both agencies. Unfortunately, OSHA, AHERA (under the EPA) and NESHAP (also under the EPA) vary in their requirements for ACM sampling.

What are you required to sample?

Building owners are responsible for locating the presence and quantity of Presumed Asbestos Containing Materials (PACM) in buildings built before 1981. OSHA’s Presumptive Rule says that thermal system insulation (TSI) and sprayed-on or troweled-on surfacing material are considered. That means that if your pre-1981 building contains these materials, you’ll have to assume those materials contain regulated asbestos material, unless you can prove otherwise through an AHERA inspection or bulk sampling by a Certified Industrial Hygienist.

Building owners or contractors will also need to investigate other non-PACM materials to ensure compliance with OSHA worker protection requirements. Wallboard, gaskets, siding and roofing are common ACMs not covered by the Presumptive Rules. Wallboard is especially tricky because it can have ACM materials applied to it; this makes wallboard a key example of where sampling variance comes in.

Composite Sampling vs. Single-Layer Sampling

“Composite sampling” means different things for the EPA and OSHA.

EPA AHERA – Although it does not officially define its meaning of compositing, EPA’s AHERA uses this term to mean “mixing samples together that were obtained separately from a homogenous area for analysis” (i.e. mixing multiple samples of the same material).
EPA NESHAP – The EPA’s NESHAP rules define a composite sample to mean a “full-depth sample” (12/19/95 Federal Register notice). In this case, a single full-depth sample could consist of multiple materials. However, the EPA uses multi-layered samples to determine if NESHAP is applicable to a project.
OSHA – OSHA doesn’t support composite sampling, and insists that “when a sample consists of two or more distinct layers or materials, each layer should be treated separately and the results reported by layer”.

Sampling Variance Requirements

EPA AHERA – AHERA allows for composited of layered bulk samples to determine asbestos percentage, regardless of surface treatments.
EPA NESHAP – NESHAP requirements for composite vs. single-layer sampling depend on the materials being tested.
Generally, the NESHAP program requires that each layer of a multi-layered system be analyzed for asbestos content when determining compliance with the asbestos NESHAP rules.
Wall Board & Joint Compound:
For wallboard systems with a surface treatment (the entire surface has a skim coat of joint compound, for example, NESHAP requires that each layer of the system by tested and reported separately. (See “add-on materials,” below.)
However, if the Joint Compound is applied in a way that it becomes part of the wallboard and acts as one material forming a system, composite sampling is allowed.
For wallboard systems where joint compound is only applied to seams, corner bead and/or nails, composite (full-depth) samples of the various layers are allowed.
Add-On Materials: Add-on materials include paint, sprayed-on materials, ceiling and wall textures. These materials must be tested, analyzed and reported separately, if at all possible. However if you cannot separate an add-on from the base material (a layer of paint from the wall, for example), a small about of the base material can be included in the sample of the add-on material.
Plaster & Stucco: If the layers can be distinguished, they must be analyzed and reported separately. However, if an asbestos-containing layer cannot be separated from another layer, the sample can contain a small amount of the non-separable layer.
OSHA – OSHA always requires separate layer sampling to determine asbestos content in multi-layer building materials.
However, employers/building owners can rebut presumed asbestos containing building materials if the employer follows the AHERA regulation, which allows for composite analysis to determine percentage of asbestos.

OSHA Sampling Variance for PACM

Fortunately, the types of materials covered under the presumptive rule don’t typically result in sampling discrepancies when using bulk sampling because they are usually not multi-layered materials. You’ll just need to find out if the bulk samples reveal asbestos content greater than 1%.

If you have questions about if, when or how you need to sample a building before your next project, please do not hesitate to contact me at dantaylor@amienvironmental.com.

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