Asbestos Information & Background

One of the most common requests we receive is “Do you conduct air quality testing?” The answer of course is yes, followed by the question, “Which contaminants are you concerned about?” If the answer is all of them, then we know we hit the jackpot and can start planning for retirement. The majority of the time, however, the answer is mold and we are able to proceed with our mold assessment and testing process as described in earlier correspondence.

Sometimes, however, the answer is a specific contaminant that is not mold. One of the most common contaminants of concern is asbestos and today I will discuss the general concepts. Asbestos was a very common building component from about 1920 to 1978, at which time EPA and the marketplace largely eliminated its use. If you are in a building constructed after 1980 you should be home free. If it is earlier construction then there may be some concerns.

The asbestos products of concern are friable, which means they can be crumbled by hand pressure. The term came from the agricultural field, where friable soil meant it was crumbly and likely good for growing crops. Friable asbestos materials are not quite so good because when crumbled, they tend to release fibers into the air for someone to inhale. We consider the friable asbestos products to have the greatest potential for airborne exposure and look for them first.

The most common friable asbestos containing materials (ACM) include thermal insulation on pipes, ducts, tanks and boilers, acoustical plaster and fireproofing. Some of these products are readily recognized by a trained eye, while others are impossible to identify conclusively without testing. Many of these friable products have long since been removed, since they represented a potential health hazard. But they still exist in older buildings and deserve some attention.

The friable asbestos products are of greater concern than the non-friable products, which do not readily release asbestos fibers. Probably the most common non-friable product is vinyl asbestos floor tile (VAT). The 9” x 9” tiles were a very common floor finish from the 1950’s to the early 70’s. Many are still around because they are durable and represent a very low health risk. I have some in my own home. One common misconception is that 9×9 tiles are asbestos and the later 12×12 tiles are not. This is not 100% true, although it may be 95% true. The manufacturers had a hard time finding an acceptable reinforcing fiber to replace asbestos, and many 12×12 tiles still had asbestos fibers during the transition in the 80’s.

Other common non-friable asbestos materials include various roofing products such as roofing felts, flashing and patching products, and cement products such as fiber cement siding, fiber cement panels (Transite™) and fiber cement pipe (Transite™). The roofing products represent another very low risk product since the fibers are encased in asphalt.

The cement products present a slightly higher risk since some damage is possible by moderate force. The Transite™ pipe is interesting in that it was used not only in drinking water systems but also in subslab ventilation ductwork systems. Many homes constructed in the 50’s and 60’s, especially split level homes, have subslab cement ductwork. It is useful to recognize when this product is present but it is not useful to panic. The pipe is very durable and does not readily release fibers. Because it is located under a floor slab it is also not easily damaged.

Hard plaster is another non-friable product that occasionally contains asbestos fibers. The history of plaster composition is interesting. The product has obviously been around for centuries and different strengtheners have been used to make the gypsum or lime cement matrix stronger. Skipping past the straw that was used in the old adobe plasters in the southwest, the most common binder used into the 1930’s was horsehair. Horsehair can be identified by its course texture and by the fact that it is frequently associated with wood lathe. As horses (and hence horsehair) became scarcer, other fibers including asbestos were occasionally used. This did not last long as plaster was largely replaced by plasterboard and then drywall by 1950. But some plasters, especially those associated with metal lathe, can contain asbestos fibers and it is important to have it tested before major renovation or demolition commences.

For the sake of completeness, we also note that some early drywall and joint compound (spackle) also contained low levels of asbestos. Any product that carried a fire rating, like drywall and ceiling tiles, almost certainly contained asbestos as the fireproof fiber in the 50’s and 60’s. The fire rated products were used mostly in commercial and educational buildings, and many were recognized as asbestos and were removed.

What is important to remember is that undisturbed asbestos building products represent a very low risk of fiber release. EPA recommends managing these products in place and has stated that vinyl floor tiles and similar non-friable products “would rarely if ever release fibers” into the environment. In general these products have been present in buildings for decades and there is little reason why they cannot safely remain as long as they are not disturbed.

If it is time for removal or demolition, however, testing is necessary to determine asbestos content and controls are needed to avoid fiber release during the removal process. We will discuss these elements in separate correspondence.

Dave Kichula
Managing Director