CPAP machine practical in workshop for someone who's very sensitive to wood dust?

[John Coloccia]

Wow! Isn't that cumbersome? Does it get hot inside?

It continually pumps fresh air, so it actually stays pretty cool. I wear the hood so I don't have to shave. For working in the shop, I use a Trend, but if I had severe wood allergies, I would seriously consider something like this if more convenient solutions didn't exist. It would probably get a bit cumbersome, sure. Anything that tethers you is cumbersome. On the other hand, you'll breathe clean air. It's really not so bad as you might think.

Why not talk to your doctor and see what he thinks?

[Doug Herzberg]

Looks like Ken Rizza did what we're talking about and wrote an article: http://cdn.shopify.com/s/files/1/038...rticle.pdf?113.

[Matt Meiser]

That's just plain bad advise in that article. I'm surprised it was published. There's no way that's coming even close to filtering the fine dust. But hey, he did seal the hose hole with some duct tape.

[Dave Richards]

That's just plain bad advise in that article. I'm surprised it was published. There's no way that's coming even close to filtering the fine dust. But hey, he did seal the hose hole with some duct tape.

Agreed. I'm glad I won't have to service his CPAP. If that's all the filtration he's using he might as well just set up a fan on the opposite side of his work and leave the face mask off.

Doug, since you're so intent on setting up your CPAP this way, you should quit talking about it and go do it. Keep a fire extinguisher handy for when the overheated power supply and blower motor ignite the dust you'll be sucking into it. If you're as sensitive to wood dust as you say, it doesn't make sense to be screwing around with trying to get something to do a job it isn't designed to do. I certainly think more of my lungs than that.

[Doug Herzberg]

Agreed. I'm glad I won't have to service his CPAP. If that's all the filtration he's using he might as well just set up a fan on the opposite side of his work and leave the face mask off.

Doug, since you're so intent on setting up your CPAP this way, you should quit talking about it and go do it. Keep a fire extinguisher handy for when the overheated power supply and blower motor ignite the dust you'll be sucking into it. If you're as sensitive to wood dust as you say, it doesn't make sense to be screwing around with trying to get something to do a job it isn't designed to do. I certainly think more of my lungs than that.

I know you're addressing the OP, but I think if you is he is worried about fines, you need to find a new hobby or spend the bucks for a real system and use it whenever you're in the shop. Neither my Trend, nor anything we're talking about here is going to remove every particle from the air supply, but both can drastically reduce what you inhale. For me, the Trend nearly eliminates the allergic reactions I have to some woods when I use it. If I can save $3-400 and improve my air quality, I'm not going to worry about burning up a used CPAP, which I would never consider having serviced. The quality of the build on the pre-filter will determine the load on the CPAP and the size of particulate which passes through the system. The OP was talking about using outside air if possible.

[Alan Lightstone]

This all assumes that you do all of your breathing through your nose, and none through your mouth, which is clearly not true. It's the same analogy why you can't deliver 100% oxygen through a simple face mask - your inspiratory flow rates are dramatically higher than the flow rate delivered by the device, and you freely inspire large quantities of air around the mask. Of course, if you taped your mouth shut, and set the CPAP machine to deliver high enough flow rates / pressures ...

In this case in your workshop, while the CPAP machine delivers air under positive pressure to your pharynx and trachea through your nose, your mouth is freely inhaling air under ambient pressure to your pharyx. There the two mix, and are inhaled into your trachea. Think of a positive pressure of 5 mm Hg of the CPAP machine being overwhelmed by the negative pressure of 35-40 mm Hg being sucked in through your mouth. Which is going to win if the mouth route isn't obstructed by soft tissues?

The CPAP machine is designed to deliver air under positive pressure to overcome obstructions to your breathing (typically soft tissue, tongue, etc...) when you are sleeping, and can't consciously overcome them. That's a very different situation than being awake and breathing "normally".

[Dave Richards]

I know he was talking about a pre-filter and outside air. He's (and it sounds like you, as well) evidently ignored what I wrote before. If the pre-filter is fine enough to trap airborne particles, it will reduce the amount of intake air for the blower. This will cause the blower to work harder than it was designed to. Then increase the length of the hose and blower current will have to be increased again due to the back pressure created.

If the OP is "very sensitive to wood dust", he should be concerned with the fine dust and he should be using equipment designed for the job.

It seems like a false economy to me. How much would it cost to replace the shop because it burned down when the CPAP goes up. The insurance company isn't likely to cover it when the fire department reports the fire was caused by a CPAP being used inappropriately. And then there's the potential health risks. How much are your lungs worth to you? Evidently not $3000.

Excellent points by Alan, too.

[daniel lane]

Dave, the OP is Doug and he wrote, "I personally am not very sensitive". I respectfully suggest that implies he's not as concerned about the fine dust as you have presumed. Also, since the "extra hose will cause the unit to overheat" argument has come up a couple of times, let's figure out how much of a risk there is.

Assuming a CPAP machine with a 1/2" ID hose, 60LPM (typical maximum flow rate), and 10cmH2O (typical pressure), and assuming the smooth bore plastic hose is actually as rough as schedule 40 steel pipe and the air temperature is 72ºF, then the pressure loss from adding 6 feet of hose to the machine is 0.0095psi, or 0.67 cmH2O - less than 7% of the machine-supplied pressure. Since 10cmH2O is typical, not machine maximum, it's fairly safe to assume that you can slightly up the pressure without overloading the machine. I would also note that 1/2" correlates to the "slim line" hoses (15mm OD, or 0.59") so it's a highly conservative calculation. A normal 22mm hose would probably have an ID of ~3/4", so pressure drop would be roughly half, given that it is inversely proportional to diameter squared. False economy or not, I think we've shown that the fire scenario isn't likely.

Alan, I thought the flow rate limitation applied just to nasal cannula, not face masks, as well. My understanding is that face masks can supply ~15lpm, where cannula are limited to ~6lpm, and typical resting breathing is ~10lpm. Of course, that makes me wonder about CPAP machines, since my research said typical flow rate was 60lpm... <ponder>


daniel

[Jim Matthews]

They make supplied air respirator equipment that's actually designed for the job.

+1 on this.

Having an overpressure ventilator force dust into your lungs sounds like a bad idea.
Even if the compressor is outside the room, it won't filter the air sufficiently.

http://www.sawmillcreek.org/showthre...rker-with-COPD

Those of us that work more by hand have less dust to manage.
Remember - the fine dust you can't see is what does the damage.

[Doug Hobkirk]

This all assumes that you do all of your breathing through your nose, and none through your mouth, which is clearly not true. It's the same analogy why you can't deliver 100% oxygen through a simple face mask - your inspiratory flow rates are dramatically higher than the flow rate delivered by the device, and you freely inspire large quantities of air around the mask. Of course, if you taped your mouth shut, and set the CPAP machine to deliver high enough flow rates / pressures ...

In this case in your workshop, while the CPAP machine delivers air under positive pressure to your pharynx and trachea through your nose, your mouth is freely inhaling air under ambient pressure to your pharyx. There the two mix, and are inhaled into your trachea. Think of a positive pressure of 5 mm Hg of the CPAP machine being overwhelmed by the negative pressure of 35-40 mm Hg being sucked in through your mouth. Which is going to win if the mouth route isn't obstructed by soft tissues?

The CPAP machine is designed to deliver air under positive pressure to overcome obstructions to your breathing (typically soft tissue, tongue, etc...) when you are sleeping, and can't consciously overcome them. That's a very different situation than being awake and breathing "normally".

For your info, the way I taught myself to stop mouth-breathing was by taping my mouth shut! This was suggested by the doctor who founded the sleep lab I was using, to the point of the best tape to use. If I breathe through my mouth now, I feel the difference and it wakes me up. I snore LOUDLY if I am breathing through my mouth, so I've get feedback from others.

I used to pretty much always breathe through my mouth. Now I do it sometimes, but it's not my regular mode. The best riders in the Tour de France will often not breathe through their mouth, especially when climbing intensely steep mountains, so they can psych the competition out - Hey, he's not even breathing hard!​

[Doug Hobkirk]

Doug and Daniel., thanks for you coming to my "defense." You are right, I did say and am not sensitive to fines (fortunately).

I've gone from posing a question I thought might trigger some interesting thoughts to figuring out how I deal with the insurance company after I burn my house down!

I don't think I should mention my idea to grow eucalyptus plants outside the shop window next to the CPAP machine so I could be inhaling their aroma!

[scott vroom]

Doug, maybe I'm missing something here but a 3M half mask with a P100 filter will filter at least 99.97% of airborne particles. Is that not enough?

[daniel lane]

Doug and Daniel., thanks for you coming to my "defense."

Doug,

You're welcome, but it wasn't meant to be a defense so much as a continuation of a civil "brainstorming" discussion. I think there have been some good points made both for and against your idea - and for the record I think it sounds neat but probably isn't worth the hassle/etc. when there are other, better options - but just as your idea can be debated, some of the proposed reasons against (or for) can also be debated. For example, I think it would be much nicer to plant rose bushes outside the shop window.

Doug, maybe I'm missing something here but a 3M half mask with a P100 filter will filter at least 99.97% of airborne particles. Is that not enough?

Scott, speaking for myself, I think that it certainly can be / should be. I use such a mask (silicone with replaceable inserts) and in the summer, I wind up with a face full of sweat under the mask. I think Doug's original hypothesis was that the CPAP could potentially keep dust away and in a more comfortable way than a mask, but of course, he was asking us all for our thoughts. Personally, I think it's a neat idea that I would never pursue, much like the solar pizza box idea I had when I was 14. (It keeps your pizza hot during a picnic!) Just doesn't seem like the payoff would be worth the effort. But that's my opinion.


daniel

[Doug Hobkirk]

Doug, maybe I'm missing something here but a 3M half mask with a P100 filter will filter at least 99.97% of airborne particles. Is that not enough?

Scott -

I posted my question "out of curiosity." Some people are literally killed by WW dust, there are lots and lots of equipment sold to alleviate the problem, etc. I personally run an exhaust fan and have the garage door open and don't think about it. I usually run my shop vac (outside) connected by about 15' of hose to my ROS when I sand. Just look at what some of the responders in this thread use!

I originally hoped my question and responses might be useful to someone and that maybe a CPAP might actually be helpful. At this point, I think the first is true and the second remains possible. I might experiment to see if exertion overtaxes the machine or too-long hoses cause problems.

So, a 3M mask is way more than "good enough" for me.

------- And I wouldn't have made this reply if I had read Daniel Lane's response - He said it better --------------

[Frank Drew]

Not yet mentioned, but tethering yourself to a hose (or any kind of line, really) that could get hung up on something could be particularly risky if you're using power equipment; imagine that you're cutting something on the table saw and someone else in the shop accidentally gets his feet snagged in your hose. No bueno.

Daniel, I think non-rebreathers can deliver 15 l/m but simple masks (no bag) perhaps not; I'd have to look it up to say for certain, though.