Phil Thien's Baffle and Bill Pentz

[John Coloccia]

http://www.ncbi.nlm.nih.gov/pubmed?c...t=AbstractPlus

That's just one study I randomly whipped out. Personally, I don't really care if you stick your head in the dust collector bag and take a deep breath, but I'd recommend against it and I'd recommend breathing clean air however it is you need to achieve that...you know, use common sense. What I won't do is spend one second arguing over this nonsense. We're all grownups here, and there's plenty of information for someone to make up their mind.

[Robert Payne]

Good reference and very well said, John.

[Art Mann]

I think it is safe to assume that the level of ill effects of wood dust are directly proportional to the level of exposure. The people in the study were certainly exposed all day every day for weeks, months or years. That is a very different scenario from a hobby woodworker who might be exposed to wood dust for a few hours a week. There is also the matter of concentration. We have no idea what the dust concentrations were in certain millwork shops in South Wales, Australia in 1999. If we are to deduce any useful information from this random study, we must know this information and we must also know the concentration in our own shops for comparison sake. I don't think anybody, including Phil, is saying that wood dust exposure at any level is harmless. It is a matter of how much and how often. If, like Bill Pentz, one believes that any amount is too much, then he should stop woodworking.

[Ty Williams]

http://www.ncbi.nlm.nih.gov/pubmed?c...t=AbstractPlus

Thanks for the link. I'll grab the full text tomorrow, but from the abstract, the results are what I'd expect. I'm surprised I missed that one, my search-fu must be weakening!

[Jim Neeley]

I think it is safe to assume that the level of ill effects of wood dust are directly proportional to the level of exposure.

People used to say the same thing about another "inhalant": smoking. They were wrong.

[Chris Parks]

Awareness of what problem, though? Statistically, the vast majority of hobbyist woodworkers never develop allergies or any sort of disease due to their woodworking hobby. A very tiny minority have difficulties. If you have data that suggests otherwise, please share it.

Because I spend a decent amount of time around doctors (working on networks inside hospitals and medical schools), I've been able to ask all sorts of doctors about the dangers of wood dust from woodworking, and I often get very puzzled looks in return.

The closest you get to "hits" are ENT's and allergists that will tell you that patients with a sensitivity to wood dust would likely have sensitivities to multiple allergens.

The entire "get the invisible fine dust" has been, and always will be, a scare tactic designed to separate people from their money.

Smoking isn't a health hazard either according to those who should know best................... the cigarette industry. Phil if you don't think wood dust is a hazard why did you bother inventing the baffle?

We all choose our level of risk in life and make assessments based on our personal beliefs. I don't care whether you believe that dust is an issue or not, your life, your risk.

[Art Mann]

People used to say the same thing about another "inhalant": smoking. They were wrong.

People still do say that and they are correct. It is you who are wrong. The rates of heart disease and lung cancer go up with the amount one smokes and the number of years they smoke. Nobody in their right mind would claim that a person died of lung cancer from smoking a single cigarette. The risk goes up with increased exposure, just like inhaling wood dust. It is just silly to claim otherwise.

[Phil Thien]

Phil if you don't think wood dust is a hazard why did you bother inventing the baffle?

To extend the life of the bags in my shop vac.

Why do I use a shop vac?

To prevent my basement shop from filling with sawdust, to save having to cleanup, and to maintain a nicer/cleaner working environment.

And I'm not saying wood dust doesn't have the potential to be a hazard. What I am saying as that there are companies out there using scare tactics in order to sell their wares.

[Chris Parks]

To extend the life of the bags in my shop vac.

Why do I use a shop vac?

To prevent my basement shop from filling with sawdust, to save having to cleanup, and to maintain a nicer/cleaner working environment.

And I'm not saying wood dust doesn't have the potential to be a hazard. What I am saying as that there are companies out there using scare tactics in order to sell their wares.

You said that all your inquiries of health professionals led to no awareness of wood dust as an issue. If that is the case are you saying that you know more than the professionals and think that they are wrong and that dust is an issue?

[Phil Thien]

You said that all your inquiries of health professionals led to no awareness of wood dust as an issue. If that is the case are you saying that you know more than the professionals and think that they are wrong and that dust is an issue?

The context of our discussion is important. This is what I actually said:

Awareness of what problem, though? Statistically, the vast majority of hobbyist woodworkers never develop allergies or any sort of disease due to their woodworking hobby. A very tiny minority have difficulties. If you have data that suggests otherwise, please share it.

Because I spend a decent amount of time around doctors (working on networks inside hospitals and medical schools), I've been able to ask all sorts of doctors about the dangers of wood dust from woodworking, and I often get very puzzled looks in return.

The closest you get to "hits" are ENT's and allergists that will tell you that patients with a sensitivity to wood dust would likely have sensitivities to multiple allergens.

The entire "get the invisible fine dust" has been, and always will be, a scare tactic designed to separate people from their money.

As you can see, I was talking about woodworking as a HOBBY, not as a profession.

The entire point of these discussions is whether someone working in their shop for a few hours a week needs to concentrate so much effort on DC.

They don't.

There is a great exchange at the bottom of this page:

http://woodgears.ca/dust/dylos.html

I'm quoting here:

And, of course, some particles are more harmful than others. On this subject, I exchanged some emails with Dwight A Kaufman, a doctor who emailed me with his comments. Here are some of his emails below. Food for thought!

Subject: Wood Dust
Hi, Several years ago I attended an Occupational Medicine Continuing Education Conference at the University of Cincinnati. The main subject was Occupational Lung Disease. I asked one of the lung specialist if wood dust cause lung disease. He answered "No" with no hesitation or reservation. Some people do develop an allergy to wood which may aggravate their asthma or hay fever. Dwight A. Kauffman MD

Read the entire exchange (there is more), it is enlightening.

To say that hobbyist woodworkers need to go to extremes to protect themselves from dust is akin to me advising my next door neighbor against using a Weber grill because of studies pertaining to coal miners and firefighters.

[Chris Parks]

Phil, your assumption is a few hours, how many is a few hours and is that like a few cigarettes? and using what timbers etc. What is an extreme measure to protect ourselves? some would say that no measures are necessary and your baffle is an extreme measure for something that prevents no danger to them. You have chosen a position on this subject just like I have but I am not telling anyone what is unnecessary, no way I am going there, I will leave that to you as you know better than all of us who choose to disagree with you. me, I will point out the alternative and leave the choice to the individual. To tell someone they absolutely don't need something of this nature is a dangerous road indeed.

[Joe Leigh]

What is an extreme measure to protect ourselves? some would say that no measures are necessary and your baffle is an extreme measure for something that prevents no danger to them.

Phil has already stated clearly that his baffle was not a protective device but only to lengthen time between filter cleanings, so you can stop using that in rebuttal.

I happen to agree with his theory that a "hobbyist" is far different from someone who does this for a living, and as such is in far less danger than that which the dust collection zealots and salesmen would have us believe. Just sounds like common sense to me.

The one thing I will agree with is that everyone has to make their own choice given their perceived level of danger and exposure. Your money, your choice.

[Art Mann]

I have personally only met one person who smoked "a few cigarettes". He was my buddy in college. He would smoke when he was drinking beer with the gang and that is all. Statistically, his health risk as a result is essentially zero. Nicotine addiction (or any other kind) doesn't allow for "a few cigarettes". Some would say woodworking is an addiction too but I don't think the amount of time the average woodworker practices it is enough to create a similar long term health risk. There are, of course, exceptions. Despite what people have claimed on this thread, the health risks of tobacco, alcohol, wood dust and most other potentially dangerous substances is directly proportional to exposure. All the wood dust studies I have seen are in industrial environments where individuals are working in high concentration areas for 8 or more hours a day for months, years or decades. In order for those studies to be of any use whatsoever, we must know the concentration of dust in the environment and the accumulated exposure time of the "victims".

Here is some food for thought. Lima beans contain a measurable amount of potassium cyanide. If it weren't already a widely distributed food crop, the FDA would never approve it for human consumption. Should we stop eating lime beans?

[Ty Williams]

So, the linked journal article earlier in this thread led me to two additional papers I hadn't found before. I've gone over them with my wife (the medical researcher, she understands a lot more of this than I do) and she's going to try searching for more of them whenever she gets a free moment at work. The three papers we've been discussing are:

Work-Related Symptoms and Dose-Response Relationships for Personal Exposures and Pulmonary Function Among Woodworkers John Mandryk, PhD, K. Udeni Alwis, MSc, and Ailsa D. Hocking, PhD

Longitudinal Respiratory Health Study of the Wood Processing Industry Henry W. Glindmeyer, DEngr, Roy J. Rando, ScD, CIH,2John J. Lefante, PhD, Laurie Freyder, MPH, Joseph A. Brisolara, MSPH, CIH, and Robert N. Jones, MD

A Survey of Size-Fractionated Dust Levels in the U.S. Wood Processing Industry Medhat I. Kalliny, Joseph A. Brisolara, Henry Glindmeyer and Roy Rando


First, two important things to point out about all of these studies:
1) The standards for the amount of respiratory problems that qualify as a "healthy" worker in the US studies would represent a "sick" worker in almost every other country with occupational health regulations. The workers still employed but qualifying as "sick" in the US studies would be on forced medical disability retirement in almost every other country in the world with occupational health regulations. The magnitude of this discrepancy is not entirely apparent until you actually go look up the standards for the EU, Japan, Austrailia, etc and compare them to the US guidelines. The US is willing to hurt a lot more people in the name of making furniture.

2) Several (I honestly forget which of the 3 my wife said brought this up) of the studies mention that their results look falsely better than reality because they were unable to count workers who had gotten so sick they had sought other employment, retired on medical disability, or died. In other words, the studies are missing the very people who got the sickest because they're no longer working in the wood processing industry. This skews the data and makes it look safer than it actually is.

So, with that in mind, what are the take aways from these 3 papers?
a) The greener the wood is, the safer it is. The researchers didn't know enough about woodworking to understand that this is what they were saying, but if you look at the rates of exposure and adverse outcomes, the trend follows wood moisture content. Wet wood is relatively safe, dry wood not as much.
b) In facilities where there were workers both in contact with wood dust (the people actually making things) and not in contact with wood dust (say, the shipping department), the workers in contact with wood dust had a statistically significant increase in negative outcomes compared to the non-contact workers. In other words, by having more than one job in a facility, the study was effectively able to show a difference in sickness between guys that breathed dust and guys that didn't and could rule out things like "well, that shop's on top of a toxic waste dump".
c) Wood dust particle size played a big role in exposure and in outcomes, just like every other kind of dust exposure. The smaller particles are inhaled and stay in fractions up to 60% (in other words, 100mg of dust goes in, only 40mg comes out, the rest stays in you) and also seemed to be responsible for the most negative outcomes (again, like just about every other dust out there). Take away from that is that 30micron bags aren't good enough, 5 micron canisters aren't good enough, etc. You really need to be aiming for "High Efficiency" (ASME AG-1a–2004, “Addenda to ASME AG-1–2003 Code on Nuclear Air and Gas Treatment”, 2004) standards, which are better than 99.97% of particles 0.3 micron and larger, single pass efficiency. I'm not aware of any commercially available filters that reach this. The closest I'm aware of are the Wynn Environmental Nanofibre filters which are MERV15 (85%-95% of 0.3-1 micron particles, single pass). This lends strong support to the "separate it with a cyclone and dump the air outside" school of thought for DC.
d) If you define "wood dust" very narrowly to mean cellulosic particles, there's some evidence to suggest that these are not responsible for the totality of the negative outcomes. There's evidence to show that the other stuff that you can't avoid producing when you machine wood is doing a significant fraction of the damage. For example, when you saw wood that's got a lot of silica content (all wood has a little, some woods have a lot), the dust from it has a lot of silica dust in it, which is well documented to cause silicosis. One of the papers mention several other specific things they were concerned about (molds, fungus, bacteria, chemicals, bits of insects, etc). All of this is stuff that can be a part of any puff off "wood dust", so it's not like you can say "OK, silica, you have to go into the DC and stay there but cellulosic dust, you can just roam free around the shop!". To me, this is kind of like the scientists arguing about whether it's the spider venom that's necrotic or the bacteria in the spider's mouth that's necrotic. It might be an interesting academic point, but, when I've been bitten, frankly all I care about is the fact that my arm is falling off, not why.



We'll see what else my wife can turn up when she actually has some free time at her lab to look for more papers. For me, the biggest change in my thoughts on DC from finding 3 additional papers is changing my mind about what to do with the "waste" air. I was firmly in the "it's too expensive to dump it outside so I have to filter it" camp. Now, given the data vs the commercially available filters, I've been converted to the idea of dumping the waste air outside and paying whatever it costs to keep the temp and humidity in the shop under control.

[Phil Thien]

Tye, your first citation refers to a study of aging sawmills, and has this as the first paragraph of the conclusion:

Seventy per cent of the dry mill exposures and 50% of the green mill exposures exceeded the occupational exposure limit for hardwood inhalable dust. None of the green mills was equipped with exhaust ventilation systems (Alwis et al., 1999). At sawmill CD, all the static machines were e€ectively exhaust ventilated. The use of ageing equipment, poor maintenance of the local exhaust ventilation systems, and leakage of dust from the joints of the central exhaust ventilation system into the working environment resulted in high dust exposures at sawmill D. None of the woodworkers at sawmills wore respirators.

Does that sound like your shop? Eight hours a day, day-in and day-out, processing lumber, using old machines with no real means of exhausting the dust?

Your 2nd and 3rd citations refer to the same research performed by Tulane. The 3rd actually refers to sizes of dust particles factory employees will see depending on their job function, and the 2nd refers to hazards.

Quoted from PubMed (http://www.ncbi.nlm.nih.gov/pubmed/18496790)

BACKGROUND:
A 5-year longitudinal study examined nonmalignant respiratory effects of wood processing dust exposure.

METHODS:
Ten study plants, investigator selected from 447 candidate plants, included 1 sawmill-planing-plywood, 1 plywood, 1 milling, 3 cabinet and 4 furniture facilities. Personal dust samples (2363) were divided into three size fractions (extrathoracic, tracheobronchial, and respirable) which were apportioned into wood solids (WS) and residual particulate matter (RPM), and used to compute each individuals TWA exposure for the 6 exposure types. Serial spirometric tests and medical, smoking and occupational questionnaires were collected with 1,164 subjects having adequate follow-up (minimum 3 datapoints over at least 2.5 years) for analyses. Forward selection regression was used to evaluate the effect of exposure on annual change in FEV(1), FVC, FEF(25-75), and FEV(1)/FVC.

RESULTS:
There were no significant adverse effects of WS exposures (overall means were 0.66, 0.32, and 0.05 mg/m(3), for extrathoracic, tracheobronchial, and respirable fractions, respectively). Statistically significant effects were only to respirable RPM in the milling facility (mean exposures of 0.147 mg/m(3) associated with changes in FEV(1) = -32 ml/year, FEV(1)/FVC = -0.48%/year, and FEF(25-75) = -0.11 l/s/year) and in the sawmill-planing-plywood facility (mean exposures of 0.255 mg/m(3) associated with changes in FEV(1) = -59 ml/year and FVC = -103 ml/year).

CONCLUSION:
Exposure to WS was not associated with significant adverse effects. Respirable RPM was associated with an obstructive effect in the milling facility, and respirable RPM was also associated with a restrictive effect in the sawmill-planing plywood facility. Finally, this study does not exclude the possibility that other exposures common to this industry can cause respiratory effects, only that none were noted in this population for wood solids for the exposure levels and durations studied.

That reads like the plywood, three cabinet, and four furniture facilities did not contribute any significant respiratory effects. Sawmill and milling center sure, but making comparisons between our shops (which we use 1-4 hours here and there) and a sawmill where you'd be working 40+ hours/week for years on end, well, it is a bit like comparing apples to oranges.