Vacuum cleaner HEPA filters are manufactured differently when compared to HEPA vacuum cleaner bags. While HEPA vacuum cleaner bags do not contain fiberglass, it must be noted that some (not all) vacuum cleaner HEPA filters and HEPA air purifier filters contain fiberglass or glass fibers. Fiberglass can be an important adaptable material for the micro filter of a HEPA filter. We recommend reaching out to the manufacturer to identity specific filters which contain fiberglass. Other HEPA filters are made from polypropylene which do not contain fiberglass. We recommend that vacuum cleaner HEPA filter never be cut open for the purpose of making a face mask or any other reason. Cutting open a HEPA filter will cause exposure to fiberglass, and also substantially reduce the filtration capacity of the HEPA filter. A HEPA filter should always be kept in its original manufactured form so it can work properly. When it works properly a HEPA filter can theoretically remove at least 99.97% of dust, pollen, mold, bacteria, and any airborne particles with a size of 0.3 microns and larger. The particle size of fiberglass is generally 2 to 9 microns in diameter, so the likelihood that fiberglass particles could pass though the HEPA filter is unlikely. Source
Here's an example of a HEPA filter that contains fiberglass. See image above.
Here's an example of a HEPA filter that does not contain fiberglass. See image above.
