Fiberglass manufactures have done such a poor job at stressing safety with their product that most people who work with it have a total lack of precaution. Because after all, if you talk too much about safety people might be afraid to line the walls and ceilings of their homes with it and that would be bad for business.
Not only do people installing it often not wear any protection, I have seen old fiberglass being removed without a proper mask or gloves.
What breaks off brand new fiberglass insulation is not as small or as potent as aged fiberglass. Fiberglass is associated with itching, which is the case when it's new. As the insulation ages it becomes more dangerous be it a home, workplace, school, church, store or restaurant. It not only loses a lot of its R value, it offgasses and shatters into tiny pieces where it escapes from the walls, ceilings and floors floating around the air. It is vented out of attics and is even sometimes installed inside of ductwork where air blows past it. It breaks down even more so if it gets wet, which can happen when there is a roof leak, a toilet overflow, a pipe leak or a washing machine overflows etc. When this happens a home that once had tolerable levels of airborne fiberglass can turn into a sick home. Family members do not feel well with varying symptoms and people have no clue it's the fiberglass behind the walls becoming airborne that is causing the illnesses. The health problems are not always lung related. While the body is busy fighting off the airborne toxin it creates inflammation and will often effect a person where they are the weakest. For some it's the lungs and upper respiratory areas, others the heart, bowels, restless leg, headache, acne, fatigue with brain fog among many other ailments. I have seen a wide range of symptoms within my own family. Not all of us were effected in the same way.
Since most people do not immediately feel the effects when they breathe it in, along with the lack of warnings, we have people all over taking no measures to protect themselves.