CPAPtalk.com

Good point.
The idea is to get fresh, clean air, but not necessarily therapy pressure.
A good use for the hated bricks!

On the few occasions when I've had to protect my lungs beyond what I trust a respirator for, I've used my boat hull-cleaning setup -- an air compressor taken from an oxygen concentrator and a Brownie's Third Lung regulator. For underwater use, this setup gives scuba people the screaming willies, but I'm still around.

Sounds like you're describing a supplied-air respirator.

Don't know if anyone noticed it, but a new poster replied to a thread from 2011. Nevertheless, it's interesting to me. Before I was tested for OSA, I thought maybe my chronic bouts of bronchitis were related to sawdust exposure.** So I borrowed a 3M PAPR (powered air-purifying respirator) from work to see if it would help. It supplies HEPA filtered air from a belt-mounted battery-powered filter unit. I liked the freedom from breathing sawdust. I ended up buying a Trend AirShield Pro https://www.amazon.com/TREND-AIR-PRO-Ai ... B002Q0Y5IU, which I still use when I'm sanding projects. I can work for hours breathing clean air without the discomfort of breathing through a restrictive filter respirator or paper dust mask.

It's occurred to me some time ago that an old CPAP blower would work fine for the task. House it in a box with good airflow and filtering, ratchet up the pressure and cobble together a couple of hoses to give you the freedom of movement you need, and you've got a DIY PAPR.

** It turned out my bronchitis was caused by undiagnosed OSA. Pulmonologist figured it out. However, I'm more careful about dust now.