HEPA air filtration

[Raymond Stanley]

Hi everybody.

I usually post in the neander section...this is my first post out of it.

I have seen the light on dust collection, even with the exclusive hand tool use that I participate in (nothing against power tools, just a personal choice for reasons I won't get into).

I have read about the question of the health benefits of air scrubbers/cleaners/filtration systems. I have also had great help from Bill Pentz.

If the woodworking air cleaners aren't sufficient for health benefits, what *can* be done to that fine dust out of the air (besides catching it at the source?).

Stuffing woodworking air cleaners with HEPA furnace filters? Homebrew solutions? Using home-brand HEPA air cleaners (honeywell, austin, etc.)? These are all solutions I've heard of. If we "know" that regular woodworking air cleaners don't provide health benefits, how can we know if these solutions would provide health benefits? Any insights?

Are the home-brand HEPA filters insufficient in terms of CFM? Does stuffing woodworking air cleanrs with HEPA filters mess with the "stock" filtration (if I stuff a hepa filter in, can I remove the inner filter?). Eek! So many considerations. Any comments would be appreciated. Thanks again to Bill Pentz for his incredible knowledge base that he has taken the time to share with everybody.

Thanks!
-Ray

[Peter Pedisich]

Ray,

Hi, I use a Festool C22 HEPA vac with all my power tools, a Rigid vac with 'Hepa type' filter for the planer/jointer/cms.
I also use two air filters; one I got from Lee Valley and a True HEPA filter by Honeywell to help clear the air from the Ridgid exhaust if I cannot route the exhaust outside.
In fact, I never use my tablesaw unless I can roll it out in the driveway. And I always leave the garage door open with large fan blowing out when the temp is above 50 deg.

My methods are obviously not ideal, but I am researching and saving up for a proper Cyclone. And I'm looking for a good mask that I can wear with my glasses and safety goggles.

Good Luck,

Pete

p.s. - by the way, great question!

[Jim Bell]

Save yourself a lot of time and money. Buy a cyclone. Mine is a Clearvue that keeps my a/c'd shop pretty much dust free.

[Art Mann]

I think your biggest problem is you have been spending too much time reading Bill Pentz's website. If you are a handtool user, then you are not going to be producing any hazardous dust anyway. If you are afraid of sanding dust, then it seems to me to be a lot more practical to wear a respirator than try to put in an elaborate dust collection system.

Just keep this in mind. The opinions of Bill Pentz are just that. He is not a professional in the field. My opinion is that because of his personal health problems, he exagerates the risks of wood dust to others. If you start digging in to the health risk information he states as fact on his website, you will find that it is either just opinion, or the studies he references are carefully chosen to ignore other equally credible studies that contradict his claims.

If you want to know dust collection methods and equipment, Bill's site is as good as any and better than most. However, if you are trying to find out about personal health risks, his authoritative comments are really just personal opinions.

If you really buy into the health risks of wood dust that Bill preaches, then my advice to you is to stop woodworking.

[Jim Becker]

My latest post to your question in the Neander Forum:
-------
Ray, a hand plane really shouldn't be creating and "dust", per se...and collecting at the source for a hand saw is going to be darn hard to do.

Sanding is the real issue at play here and there are any number of ways to help with that, including a downdraft table or an air filtration system positioned right at the bench that sweeps the fines from sanding away from you with enough air flow. Wearing a powered face shield when sanding can also help if you really want to get into such gear. (I wear one when sanding at the lathe)

A shop vac is not what you want. Shop vacs move a small amount of air at high pressure. "Dust collection" requires moving a large amount of air a low pressure...both from the standpoint of point-source pickup, such as with stationary power tools as well as for the down-draft or "back-draft" type setup I mentioned above. You can build either or both of the latter using a surplus HVAC fan system if you want to do so...

[Wilbur Pan]

If the woodworking air cleaners aren't sufficient for health benefits, what *can* be done to that fine dust out of the air (besides catching it at the source?).

What Bill has to say about the health risks of wood dust, dust collectors, ducting, and cyclones is accurate. However, Bill's own measurements have shown that even in shops where well designed dust collection systems are in place, that dust inevitably escapes into the air. Because of this, you need a back up plan to deal with that dust.

The best way is to open a window and exhaust the air to the outside. Obviously, this is not practical or possible for every shop. Living in a hot or cold environment wastes a lot of A/C or heat if you choose this method, and if you have a basement workshop like I do, there may not be an option for a venting system.

So that leaves air cleaners. The key is to get enough air cleaning capacity for your workshop. Conventional wisdom says that 6-10 air exchanges per hour is good. In my workshop I aimed for 25 air exchanges per hour, which should clear airborne dust very effectively: about 99.99% of the dust would be captured in 30 minutes. Unlike trying to upgrade your dust collection system, adding air cleaner capacity is easy -- just install another unit.

You can calculate the number of air exchanges per hour with this formula:

60 x CFM of air cleaner(s) / volume of workshop

And despite what Art says, there is considerable peer reviewed evidence (http://www.sawmillcreek.org/showthread.php?p=454754#post454754) to show that wood dust exposure is harmful to one's health. This is a fact. However, one does not need to stop woodworking to deal with this, any more than one would need to stop driving because of the risk of dying in an accident.

[Dick Sylvan]

Save yourself a lot of time and money. Buy a cyclone. Mine is a Clearvue that keeps my a/c'd shop pretty much dust free.
What type of a/c do you have? I am about to do that and am concerned about dust and the a/c unit. I also plan on getting a Clearvue.

[Henry Cavanaugh]

Hi, I use a Festool C22 HEPA vac with all my power tools

Peter iam considering a new vac to replace my noisy shop Vac. I use a DC for larger tools. I was going to buy a Fein for less money than Festool CT22. I believe the Festool Hepa is an upgrade. Have you noticed a difference between the two different filters. Iam still on the fence between Festool, Fein, Alto and would enjoy anyones imput. I will be using it for a new Domino and my preexisting Bosch sander

[Peter Pedisich]

Hi, I use a Festool C22 HEPA vac with all my power tools

Peter iam considering a new vac to replace my noisy shop Vac. I use a DC for larger tools. I was going to buy a Fein for less money than Festool CT22. I believe the Festool Hepa is an upgrade. Have you noticed a difference between the two different filters. Iam still on the fence between Festool, Fein, Alto and would enjoy anyones imput. I will be using it for a new Domino and my preexisting Bosch sander

Henry,

All CT22 dust extractors now ship with HEPA filters. I got mine before this and swapped out the 1 micron filters that were std and did not notice any difference in any respect. It's for peace of mind.
I agonized for months should I get the Fein or Festool or Porter Cable.
To get the bags and HEPA filters for the Fein raised the price significantly and still no variable speed or flat top to put the tool down (very convenient).
I like Ridgid SNR vacs for shop cleanup and Festool CT22 for dust extraction. Although if someone gave me a Fein I'd be VERY happy! They are awesome vacs - tha plastic they are made from is very tough, and they are the quietest vac I've ever heard.

Pete

[Art Mann]

What Bill has to say about the health risks of wood dust, dust collectors, ducting, and cyclones is accurate.

One thing Bill claims is that OSHA standards for an industrial woodworking environment, where workers are exposed for 8 or more hours a day, are not adequate for the hobby woodworker. Are you saying that is accurate? If so, what studies can you point to that lead you to believe this is true? The reason I ask is that Bill has published information on his website that is not substantiated by actual research. Most of it comes from the opinions of his own physician. The research he does reference is old and mainly from Europe and has been contradicted by at least one study done here in the US. I don't fault Bill for trying to do the woodworking community a service, but I think his own serious respiratory problems have clouded his reasoning and this is reflected and on his website.

[Jim Becker]

May I remind folks that the OP is concerned about dust collection in a primarily Neander environment. Let's not get off track discussing the merits of an online resource, etc.

Jim
SMC Moderator

[Art Mann]

Jim,

The only reason I bring up Bill Pentz and his website is that the original poster sited it as a major source of his information. That explains to me exactly why someone who only uses hand tools would worry about dust exposure. I am simply calling into question his basic source of information which I consider to be misleading and sometimes downright inaccurate. The point is that someone should always take a healthy skeptical look at the accuracy of the information he is reading.

[Raymond Stanley]

Thanks everybody for their contributions. I appreciate all the help, regardless of position. I agree that it is healthy to be skeptical, but the fact of the matter is I'm having lung-oriented reactions to wood in an exclusively hand tool environment. So I'm just going to operate on the assumption that there is dust that needs to be collected. I haven't had physical measurements of dust in the air hand tool woodworking - that would be the only sure-fire answer.
Saying that, I'd just like to move forward on getting people's experience with air filtering.

I picked up an Austin Air HEPA filter off craig's list, so I'm going to try that for a while. Hopefully it won't get plugged up too quick.

-Ray

[Wilbur Pan]

Raymond,

The HEPA filter you describe will help, but I too would be concerned as to how quickly it might get filled up, and whether it will circulate an adequate amount of air. I would keep it as close as possible to where you are working.

Despite the fact that Raymond is in a hand tool environment, sawing, whether by hand or by machine, still generates a lot of dust. Consider this: suppose I need to rip a board. I can do this in a number of ways: tablesaw, bandsaw, or by hand. In all cases, I'll have to make a cut along the same length of wood, which converts the wood in the kerf of the blade to dust. Regardless of which method of ripping I pick, more or less the same amount of wood is going to be converted to dust, with the only variable being the width of the kerf of the blade of the saw. Certainly a tablesaw has the potential to create more dust because the kerf of a tablesaw blade is typically wider, but a bandsaw blade and a handsaw blade have kerfs that are pretty close in width, which means that either method will generate similar levels of dust for the same cut.


One thing Bill claims is that OSHA standards for an industrial woodworking environment, where workers are exposed for 8 or more hours a day, are not adequate for the hobby woodworker. Are you saying that is accurate? If so, what studies can you point to that lead you to believe this is true? The reason I ask is that Bill has published information on his website that is not substantiated by actual research. Most of it comes from the opinions of his own physician.

Yes, I am saying that OSHA standards may not be adequate for an individual woodworker. In deference to Jim, instead of a lengthy post, here are some links that will answer your concerns.

I've already posted a link to peer reviewed studies showing the link between dust exposure and heath issues (http://www.sawmillcreek.org/showthread.php?p=454754#post454754).

Why the concept of "safe levels" of dust is a red herring, and why any level of dust exposure may be hazardous to an individual wood worker. (http://www.sawmillcreek.org/showthread.php?p=454805#post454805)

Why OSHA standards may be a moot point, considering how much dust we generate in our shops. (http://www.sawmillcreek.org/showthread.php?p=454852#post454852)

And as far as the opinion of Bill Pentz's physician goes, I also happen to be a physician. A pediatric oncologist, to be specific.

Regardless of how Bill chooses to present information on his website, the fact remains that wood dust is a hazardous material, and can cause severe health problems at any level of exposure.

I am interested in the study you are talking about. Do you have a reference?

[Steve Sawyer]

Argue how you will, I think we can all agree that the less dust we breathe, and the less dust that gets on our shoes and clothes and carried around to the rest of the house and the family the better.

While hand tools do indeed produce significantly less fine dust than power tools, they still produce dust. Take a very well sharpened plane, use it for a few minutes, then look down inside the throat. What do you see? A coating of fine dust. Admittedly it isn't airborne until you take a bench brush and whisk away that dust, or put it up to your mouth and blow it away, but it's going to get airborne to some extent.

I have a DC fitted with a Wynn Environmental half-micron cartridge. Yet I noticed that when working in the shop for more than an hour or so, solely with hand tools, I would develop a dry cough from the airborne dust. Admittedly I was probably kicking up some dust that had escaped the DC and had settled on surfaces or floor, but it was something I needed to address.

I bought a small 450 CFM 1-micron air cleaner (a Jet AFS-500), installed a timer in the power cord and there was an IMMEDIATELY NOTICEABLE IMPROVEMENT. I run it on high speed when running any power tools, on low speed at all other times, and I leave it running for an hour on low after I leave the shop.

I know that I'm more comfortable, I'm probably reducing the negative health effects of breathing wood dust, and I know that my hobby isn't spewing fine dust all over the laundry in the adjacent area.

If you have an air cleaner, then putting high-efficiency filters that can remove very small particles - the smaller the better - is a good thing. If I find some that will do .5 microns for this air cleaner I'll put 'em on, but I know that I'm making a significant improvement by just filtering down to 1 micron. I'm not going to lose any sleep over it, but I'm doing what I can.

[Dave MacArthur]

Raymond,
I have the JET system, with regular supplied filters. Not sure of their effectiveness, but I do find less dust on the cars the next morning when I leave it running for 2-4 hours on it's timer, and the air smells "clean" in the morning.
I'm also interested in where I can buy some 12x24" filters for the JET air filtration system, which would be HEPA.

[Art Mann]

I would encourage everyone to follow the links Doctor Wilbur Pan provided in his last post. Then ask yourself why he needs to reference studies done in Nigeria, Pakistan and Sweden to make his point. Try to find out what the conditions were in the factories studied and ask yourself whether that has any relevance to your own wood shop.

Doctor Pan makes the statement that there is no safe level of wood dust. If that is true, then we should all stop woodworking right now because it is not possible to reduce your exposure to zero.

Doctor Pan advises that you should fill your shop with air filters such that 99.99% of the dust is captured within 30 minutes. Doesn't that mean that for 15 of those 30 minutes, the air will be contaminated with at least 50% of the maximum contamination? If, as Doctor Pan says, no level is safe, then how can this be a good recommendation?

I have never claimed that dust in the hobby woodshop is not hazardous. I use a dust collection system continuously. I designed the system partially from information obtained from the Pentz website. I also use a respirator when doing high risk activities like sawing MDF or sanding. I will have to say, though, that one has to be truly misinformed to be worried about the level of dust created by a hand plane. My opinion is that this sort of hysteria has been largely created by Pentz and his legion of faithful followers. My only goal in posting all this is to encourge people to be skeptical and verify claims made by anyone, whether he is an amateur woodworker with severe respiratory problems, a pediatric oncologist, or an engineer and hack cabinet maker like myself.

[Wilbur Pan]

Art,

First of all:

Doctor Pan makes the statement that there is no safe level of wood dust. If that is true, then we should all stop woodworking right now because it is not possible to reduce your exposure to zero.

You must have missed where I said earlier in this thread:

However, one does not need to stop woodworking to deal with this, any more than one would need to stop driving because of the risk of dying in an accident.

Now, the fact that the studies cited were done in other countries has no bearing on their validity. All of these studies had control groups. These studies are published in reputable peer reviewed journals.

Allow me to explain further what I mean by "no safe level of wood dust".

I've attached a picture of a dose response curve. The numbers aren't important for this explanation -- just the shape and behavior of the graph. All of the studies cited showed a dose response relationship between dust exposure and health issues. A dose response relationship means that the higher the exposure, the greater the effect. It should be noted that as you move to lower doses, the graph doesn't run straight into the x axis. Rather, it approaches the X axis asymptotically.

From a clinical standpoint, what this dose response curve means is that for a given population of woodworkers, a given level of dust will affect a certain percentage of the population. If we took all the SMC members and exposed them to a dose of wood dust, some percentage of us would come down with pulmonary disease. A bigger dose means that more of use would get that disease. A smaller dose means that less of us would get that disease.

When OSHA or any other regulatory agency sets guidelines, this is how they pick their exposure limits. An OSHA approved level of exposure does not mean that being exposed to that substance will not result in any disease occurring from that exposure. It means that the incidence of disease in the population is considered "acceptable", which is partly a function of the science, but also is partly a result of nonscientific influences. OSHA knows that some number of woodworkers will come down with pulmonary disease due to wood exposure even if their guidelines are followed to the letter. It's just that the number of these cases is considered to be "acceptable".

Besides, the exposure of people involved in woodworking to dust is probably worse than we think. OSHA levels for total wood dust exposure are 15.0 mg/m3. ACGIH guidelines for total dust exposure is 1.0 mg/m3. The fact that a sawing or sanding operation can generate dust levels that are 3-6 times the OSHA guidelines makes the OSHA guidelines a bit of a moot point. If you generate 90 mg/m3 of dust while sanding (Hursthouse A et al. A pilot study of personal exposure to respirable and inhalable dust during the sanding and sawing of medium density fibreboard (MDF) and soft wood. Int J Environ Health Res. 2004 Aug;14(4):323-6.), then to meet OSHA guidelines you'd have to do one sanding operation, then take the next 6 days off. In other words, anyone that works in woodworking are automatically subjecting themselves to dust levels higher than what OSHA deems to be acceptable. Then there is the question of whether OSHA guidelines are really acceptable, which I've already touched upon.

Now suppose you happen to be that unlucky individual that happens to get pulmonary disease from wood dust exposure at OSHA approved levels. It doesn't matter that your level of exposure was OSHA approved, or that you weren't exposed to as much dust as someone else. You still have health issues from wood dust exposure.

That's why I say that there is no "safe" level of exposure to wood dust. A "safe" level implies that there is some magic threshold of dust exposure such that if you stay below it, you never have to worry about health issues. That just isn't the case. You assume a level of risk whenever you are exposed to wood dust. And the fact is, there are individuals that have developed health issues from what we might consider to be "low" levels of wood dust exposure.

However, I also think we can intelligently decide how much risk we are willing to take. I certainly am willing to take the risk, otherwise I wouldn't have set up my shop in probably the worst possible situation for dust control: a basement workshop with no windows or ventilation to the outside. But I also made sure that my dust collection and my air cleaning capacity is at a level that I am comfortable with. I really wish I had a better environment from a dust control standpoint, but at this point improving my shop location would mean buying a new home.

Again, the studies I cited are controlled studies that are peer reviewed, and are obtained from searching the literature database at Pubmed (http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed), which is the biomedical literature database run by the NIH. I didn't come to my conclusions about the risks of dust exposure because of Bill's website. I came to these conclusions by searching and reviewing the medical literature, and from basic principles of population medicine.

Look, I agree with you that Bill has not done a very good job documenting his claims of health issues related to wood dust on his website. I've even called him on that myself. But to then say that there is no such evidence "substantiated by actual research" or that such concerns are "hysteria" is equally inaccurate. Hopefully my explanation of dose response relationships clarifies how wood dust affects us all.

I'm still interested in the contradictory study that you mention. Can you provide a reference?

[Art Mann]

Doctor Pan,

The study to which I referred previously was done by the Tulane University School of Medicine. I believe it was published in October, 2005. I could not locate the actual paper again, but assume you can locate it. A Google search produced dozens of hits, all of which said the same thing. If anybody else is interested, Google "Tulane Wood Dust Study" or similar.

I was wondering if you were going to refer to a response curve illustrating that there is no level of wood dust exposure that has zero probability of ill effects. If I looked long enough, I could probably produce a similar curve illustrating the known fact that exposure to Tylenol causes liver damage and that no level of exposure has a zero probability of adverse effects. Yet, I will wager you have advised your patients to take this medicine as a pain reliever at one time or another. A person can state something that is, strictly speaking, very true but is irrelevant nevertheless.

Nobody that I know of is advocating that one should ignore the risks of inhaling wood dust. However, I think hysterical overreaction like what you find on the Pentz website does at least 3 bad things. 1) It may cause people like the OP to be unduly concerned about a vanishingly small risk and perhaps waste money on an over elaborate system they don't need. 2) It may cause people to just give up on woodworking because they think it is too risky compared to other hobbies. 3) Thinking woodworkers may see the hysteria for what it is and, as a result, just dismiss the whole idea of dust control as nonsense.

[Wilbur Pan]

Art,

First of all, you can stop referring to me as Dr. Pan. If you're one of my patients, you can use the title. Here you can call me by my first name.


I was wondering if you were going to refer to a response curve illustrating that there is no level of wood dust exposure that has zero probability of ill effects. If I looked long enough, I could probably produce a similar curve illustrating the known fact that exposure to Tylenol causes liver damage and that no level of exposure has a zero probability of adverse effects. Yet, I will wager you have advised your patients to take this medicine as a pain reliever at one time or another. A person can state something that is, strictly speaking, very true but is irrelevant nevertheless.

I don't know why you keep putting words in my mouth. Of course there are risks regarding Tylenol and liver damage. Of course I advise patients to take it. I prescribe drugs that are far more dangerous than Tylenol all the time, because the benefits outweigh the risks. And I have not advocated that anyone stop woodworking because of the hazard of wood dust exposure, despite your "conclusions" to my posts here.

As far as the Tulane study goes, the study that you reference was commissioned by the American Forest & Paper Association and 18 other wood industry trade associations, and is not a peer reviewed study. The study was not published in any biomedical journal and was released by the AF & PA themselves. The take home message according to the AF & PA, is that they "do not see any need for changes in [exposure] levels or safety equipment" (http://www.woodworkingpro.com/publication/article.jsp?id=404&pubId=1).

At the very least, there is obvious conflict of interest given the sponsors of the study. Peer reviewed studies published in academic journals like the ones available on Pubmed are considered to be of higher quality and reliability than commissioned studies by trade organizations with an interest in the outcome.

Because of these issues, I would be much more skeptical about the Tulane study than any of the others I have referred to.

[Jim Becker]

Ok, folks...time to cool off. Points made. Points taken.

This thread is temporarily closed to further posting as it has vastly strayed from the original poster's intent and question(s).

Jim
SMC Moderator