Should I be concerned about Fiberglass?

Jan 11, 2019

As the health effects from asbestos became more apparent in the early 1900s, a replacement material was sought that had similar versatility. The material that was selected as an alternative to asbestos became known as fiberglass. It is used throughout a variety of industries because of its adaptable nature, strength, and low weight. As its presence became more common, concerns grew about its potential health risks and some feared it was the new “man-made asbestos”.

Overview of Fiberglass

Unlike asbestos, which is a naturally occurring group of fibrous silicate minerals, fiberglass is a man-made material. While it wouldn’t be used commercially until the 20th century, there were artists who used glass fibers for artwork as early as the 18th and 19th centuries. Glass fibers began to be used commercially after accidentally being discovered by exposing molten glass to a hot jet of air which created the material glass wool. After the glass wool product became commercially available, it was further improved by strengthing the fibers with polyester resin or epoxy. This new combination is what we call fiberglass.

Health Effects

The primary health effects of fiberglass are skin and eye irritation. Once fiberglass touches the skin it can cause contact dermatitis and create a skin rash. Eyes can become reddened and irritated after exposure. There are no long term related health risks related to these types of exposure. Exposure to fiberglass can also cause upper respiratory irritation which causes sore throats and noses. The exposure to smaller respirable fibers has not been adequately evaluated.  As of the publishing of this article, the consensus is that fiberglass exposure does not cause cancer in humans. Despite a previous classification, now the International Agency for Research on Cancer does not consider fiberglass to be carcinogenic. Lastly, it can cause irritation to the stomach and digestive tract if ingested.

Methods of Testing

Fiberglass can be tested for in the air and settled dust. The primary air testing method for fiberglass is phase contrast microscopy (PCM), which is also the primary method for testing asbestos in the air. PCM testing is a fiber counting method where all fibers are counted and often compared to the EPA clearance level of 0.01 fibers per cubic centimeter. The drawback for this analytical method is that the test cannot directly test for these fibers and takes into account all fibers present, meeting certain criteria. Another more comprehensive method would involve testing for man-made vitreous fibers (MMVFs) which involves testing for the fibers using a combination of analytical methods. These methods are polarized light microscopy (PLM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The MMVF testing methods are also used to test settled dust for fiberglass.


While fiberglass can impact health, its effects pale in comparison with those related to asbestos. Due to the size of some fibers, they are not able to penetrate deeper into the lungs like asbestos. More importantly, the body can biodegrade them once inhaled.  If you have concerns related to fiberglass exposure, please contact Indoor Science to evaluate your property.