I work in a machine shop and working the burr bench with plenty of fine grinding of aluminum is a regular part of the job. Depending on the type of work I am doing/ set up changes the mask I use but I ALWAYS use a mask. Like a previous post already said, one of my first days doing it I didnt think a mask was necessary and I felt like I had allergies the rest of the day (congested and constant sneezing) When I got home and showered I noticed a ton of black snot coming out. Now If I am working in a well ventilated area with a fan or some kind of wind flow sufficient enough to blow most of the dust away then Ive gotten away with the cheap nuisance dust masks, both the surgical mask style and the molded style. If I dont have any kind of wind flow I use a
half mask and change the filters regularly. It might seem uncomfortable at first but I can only imagine that major lung issues would only be worse later in life.
The cool thing about the half masks is that you can buy different filters for different things you might need to do, regular dust particulate filter, n95 filter, and I have even seen cartridges for vapors as well if you're painting or welding. Just a good overall investment to make for yourself.