The joke goes that MDF is sawdust and glue… and that is close to the truth. The “glue”, when machined, can range from severely toxic to just an irritant. Unless you live in the CA, there is no insurance you’re working with the low toxicity stuff. Some of the MDF in the market comes from China and has been found to contain carcinogens, mutagens, and teratogens. There are issues of chemical exposure with MDF and other materials, it’s not just about the particles.
MDF is an example of a friable (easily crumbled) material. When friable materials are machined, they yield particles that can very dangerous to your health. Other problematic materials are FR4, carbon composite, Garolite, and fiberglass. Many hardwoods - especially exotics - can also be very nasty.
Oh, also anything with Beryllium (or Plutonium) in it - SUPER NASTY!
The N95 is not sufficient. You need a respirator that has a positive seal and uses HEPA filters or equivalent. Simple saw dust masks don’t come anywhere near to being safe.
Using a mask is good but… the MDF particles get everywhere, contaminating the room, your clothing, your hair and so forth. You land up carrying the nasty particles with you, exposing yourself and others.
To be safe, you need a sealed enclosure and a vacuum system that pulls enough air to ensure “lifting”. Your hose is clearly insufficient.
It’s all about limiting exposure. Anything is better than nothing and perfection is the enemy of good enough. Most CNC purchasers do not budget anywhere near enough to safely use their machine. The good news is a few changes and you can dramatically reduce your exposure. We can work within most budgets; some creative solutions can be most effective.
I can help you offline, message me. You can also look up my postings on air and ear safety. I’m about the only person who uses the work “friable” so that will help locating my air safety postings.
Here is a good place to start:
mark
P.S.
Don’t forget your hearing exposure. Without the proper protection, the prolonged exposure is ear damaging.