Southfield, Mi
In Southfield, Michigan, "Bonnie" was a construction manager who wanted some asbestos testing done. She'd worked with other labs before, but was curious about the general process. So, since she asked, we thought it would be a good idea to explain a little! While there is significant awareness in the general public about the negative potential health effects of asbestos and also significant awareness about what sorts of materials are at risk of containing asbestos, we find that very little is known about what exactly our lab does to produce results about whether or not materials submitted contain asbestos or not. It is definitely not as simple as dumping the material into a hopper on a magic box — unlike most detection of environmental contaminants, the detector is people rather than a computer!
The analytical process for asbestos was initially defined in EPA-600/M4-82-020 from 1982. This is a relatively short document (4 pages) that describes the basics of identification and quantitation of asbestos in bulk building materials. This method was not intended to be comprehensive, but was intended as a starting point to get the ball rolling so to speak. This method was greatly expanded on in 1993 with EPA/600/R-93/116 in 1993. This is a far more comprehensive (98 pages) method that still forms the basic text of asbestos analysis. It is worth noting that many asbestos regulations were put in place in the mid-late 80s, so they require the 1982 method, even though the 1993 method technically supersedes it in every way. Luckily, any work performed in compliance with the 1993 method will inherently compliant with the 1982 method, so there is no conflict in using any referring primarily to the 1993 method.
This method primarily involves two microscopes and a set of calibrated liquids known as refractive index (RI) oils. The microscopes are a polarized light microscope (PLM) and a stereoscope. This was something that confused Bonnie a bit; she'd taken a lot of asbestos testing samples from projects in Southfield, but she didn't know what these "scopes" were. Don't worry, it's simple enough!
The stereoscope is a simple light microscope that allows 3-D viewing of materials at between 7x and 40x. This allows the analyst to perform an overview of the entire sample to ensure homogeneity and create a plan to create a representative subsample of the material that can fit onto a microscope slide for evaluation. Common procedures involve grinding with mortar and pestle, teasing with forceps, melting with heat and/or chemically, burning with a butane lighter, and teasing apart with hand tools. Since the list of procedures is necessarily as long as the list of possible materials, the preparation stage is genuinely an art. This is one area where training and experience really, really matter in producing quality results.
These slide preparations are then evaluated on the PLM microscope. The PLM is the most commonly used microscope for any sort of rock/mineral identification, and is the primary identification technique used for asbestos. It features two sets of polarizers (not unlike sunglass lenses) and a circular rotating disc stage. Since minerals will always have a distinct repeating crystal structure, being able to rotate the material in various states of light polarization allows the analyst to observe a wealth of properties of any structure at a magnification between 40X and 400X to provide preliminary identification of possible asbestos. This preliminary identification is then confirmed (or not) using refractive index oils. Because (as said above) minerals will have distinct repeating crystal structures, light will bounce through different minerals at different rates via a process known as dispersion staining that converts the speed of light through a material into a visible color assuming the proper RI oil is used properly. This process allows the analyst to check for the known "fingerprint" of how quickly light will move through a particular mineral in different orientations. Only once a particular structure satisfies all of the above criteria can it be identified as asbestos.
We hope this has clarified a few things for those looking for asbestos testing in Southfield, Michigan—or anywhere beyond! PEL Laboratories always tries to keep our customers informed on how our processes work. But, if you still have any questions, please feel free to call or email us. We're always happy to help!