OSHA has Permissible Exposure Levels for asbestos manufacturing plants. Not something you want in your living room.
The current guidance from EPA is not overly clear. Since fiberglass contains non respirable particles – that means it can stay in your lungs once you breath it in – we tend to advise levels of zero. Asbestos also has irreparable particles.
Please don’t use fiberglass HVAC filters.
Do use HEPA (paper) HVAC or heating system filters. The industry is now making plastic HEPA filters. We do not recommend plastic filters. The manufacturers state these filters can safety be rinsed with water. Not so. The water remains trapped in the folds of the plastic. Water encourages mold growth. Mold is in the dust in the filter. Definitely not designed for a healthy home.