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Sawdust, how dangerous is it?

brianmexico's picture

Just a simple question for those of you more knowledgable than I. I understand the logic behind ear and eye protection in the shop but sometimes I have asked myself while working "should I be wearing a mask?, how dangerous is this sawdust floating around me?" How danderous is regular pine sawdust? Is it just hardwoods that do damage? Do I always have to wear a mask? If I work in a well ventilated area can I get away with no mask? What kind of guideline should I use because I do want to be safe in the shop.


Thanks for the input,


Brian M

Robin's picture

(post #78485, reply #33 of 40)

I too, having a relatively small shop - 13 x 24 - and it being new, have been waiting on the dust collector and air cleaner.  It does make sense that if the air cleaner is mounted on the ceiling, that it is pulling the dust past you and in effect increasing your exposure, but I guess this only applies to those dust particles small enough to truly be airborne.  Can you mount an air cleaner lower in the room - say waist high - and get the same cleaning effect?  I guess really the most important thing to do is spring for the dust collector and ducting to get the dust before it has a change to become airborne.  A lot to think about.

"Well-behaved women rarely make history."from the Sweet Potato Queens' Book of Love

 

HowardAcheson's picture

(post #78485, reply #34 of 40)

See if this answers your question.

The two most important criteria for an air cleaner are the CFM and the filters. You want a CFM factor that will clean the size of your shop and a filter that removes the particle size that you are concerned about.

To determine the size or required air flow, use this formula: Volume of your shop (Length x width x Height) times Number of air changes per hour (typically 6 - 8) divided by 60. This will give you an answer in Cubic Feet per Minute which is how air cleaners are measured. MOST AIR CLEANER MANUFACTURERS RATE THE CFM OF THE FAN ONLY, but there are losses due to the filters. If you are building your own or if the air cleaner you are purchasing rates only the fan, figure you will lose about 25 - 40% for filtering losses.

As important as the air cleaner size is how and where you mount it. Try to mount at about 8-10 feet above the floor (no lower than 6'or 2/3 of the floor to ceiling distance if less than 8' ceiling). Mount along the longest wall so the intake is approximately 1/3 the distance from the shorter wall. Mount no further than 4-6 inches from the wall.

The exhaust is the largest determiner of the circulation pattern. You are trying to encourage circulation parallel to the floor/ceiling so ceiling mounting is not recommended. Use a smoke stick (or a cigar) to observe and maximize circulation. Use a secondary fan to direct air to the intake if necessary. Also, consider that a standard 24" floor fan moves a lot of air and, in some shops, just positioning it in a doorway with a window or other door open can accomplish as much or more than an air cleaner. It's all in the circulation patterns.

The exhaust is the clean air so that is where you want to position yourself. Do not place the air cleaner over the a dust producer. That will guarantee that the operator will be in direct line between the dust producer and the air cleaner. The operator wants to be in the clean air stream. If the dust has to pass your nose to get to the air cleaner, you get no benefits. If you have an odd shaped shop, two smaller units may be better than one large one.

DO NOT RELY ON A AIR CLEANER TO ACT AS A DUST COLLECTOR. The purpose of and air cleaner is to keep airborne dust in suspension and reduce airborne dust as quickly as possible AFTER THE DUST PRODUCER HAS BEEN TURNED OFF.

Howie.........
Jimma's picture

(post #78485, reply #35 of 40)

I have had the Oneida 1.5 HP system for five years with ducting designed by the company which places collection points at all of the stationary tools. My only modification to the system has been to add a secondary cyclone (off-the-shelf plastic can-top unit) to catch the heavy flow of chips from the planer and jointer. I did this because it is much easier to empty and because it works well.

If you put your hand at any of the collection points while the Oneida DC is on you'll feel suction, more of it where the larger diameter inlets are. This isn't scientific, but it proves the system is working and, hopefully, is catching a lot of the finer particles.

HOWEVER, my shop is not dust-free and there is an accumulation of sawdust, larger particles no doubt, at each machine including the band saw and the cabinet saw, even though the bandsaw has two DC ports and the cabinet saw is fitted with a four-inch overhead blade guard/DC collector as well as the usual five-inch bottom port of the cabinet. Most of the dust that doesn't get sucked up is dust that collects/deposits on the tops of the saws.

How do I know there is a lot of dust NOT getting into the system? My wife comes into the shop once in a while and points to all the fine accumulations on various things (chairs, stereo, tool tops, etc.) that never got picked up by the Oneida OR the overhead air cleaner which I've also had for about five years.

So, what to conclude? Keep that dust mask handy and do as much sanding outside as you can while hoping that's enough.

jonsherryl's picture

(post #78485, reply #4 of 40)

Brian, I think Rob's given you some good advice. Fine sawdust, regardless of the species, desiccates mucous membranes and clinical history strongly indicates that long term exposure to it can lead to cancer in the respiratory system...I don't think the correlation is as tight as it is between smoking and lung cancer, but there does seem to be a connection between woodworking and nasal cancer. This type of cancer isn't all that common, however, it's still worth doing what you can to avoid the risk.


Depending upon the species, there are all kinds of other toxic risks. The extractives in some woods are literally poisonous in high enough doses and even small doses can be dangerous to individuals that have other health complications. For example yew contains compounds that affect the cardiovascular system and could be a problem for anyone with a heart condition...But the bigger risks involve allergic reactions. The various wood extractives in literally hundreds of species prove to be allergens to only a small percentage of people, but if you're one of the unlucky ones, it can take only minute doses to kick off serious symptoms. And finally, toxins created by the molds and other fungi that decay wood can also be dangerous...so, the issue isn't just one of avoiding certain species of wood.


Don't mean to scare you. There are a lot more dangerous things in life than woodworking...for example; car racing or messing around with someone else's wife...and I think, even in woodworking, the risk of injury while using power tools presents a greater danger than the chemistry of the wood itself.

EdHarrow's picture

(post #78485, reply #9 of 40)

Sawdust was one of two things that took "Poppie" way before his time.  I'm sure his pipe didn't help, of course.  Nothing theoretical here, lung cancer got him; he spent a lot more time in a cloud of sawdust than in a cloud of pipe smoke.

jjf's picture

(post #78485, reply #10 of 40)

While I would not put sawdust in the category of normally causing cancer I would put it in the category of causing lung and upper respitory problems.  You would with both wear a mask at least in most situations.  The difference is that in the second category I would not become fanatical and wear one when all I was doing was cutting a piece or two.  Put it perspective.  If you walk through the woods you would be breathing in cancer causing agents (VOC's) but do you wear a mask normally out there.  Life is enough of a bummer without getting over excited about sawdust.

HowardAcheson's picture

(post #78485, reply #13 of 40)

Saw dust is listed by the US Gov't as a "Group 1-Known Human Carcinogen"

Go here for info: http://ntp-server.niehs.nih.gov/htdocs/liason/65FR17891.pdf

Howie.........
DougF's picture

(post #78485, reply #12 of 40)

Brian,


A link to Oneida, one of the better manufactors of DC systems.  One of the tech articles is a list of woods and the conditions they can cause: http://www.oneida-air.com/news.htm.  You may also want to review the article on air filters.  I'm not sure I agree with their conclusions but they make a compelling case against them.


Bottom line: Bill CLinton was right - you really can't be too careful about what you inhale.


DOug

tomytinker's picture

(post #78485, reply #36 of 40)

Grab yourself a box of the simple white dust masks to start. There are several brands and ranges of micron filtration pricing from $20 - $40 for a box of twenty and are sold just about everywhere. You can use them several times before you have to throw them away (if you don't mind smelling the stench of your old breath).  They are easy to put on and off, relatively comfortable, and are way better than nothing.


I have allergies and have very little problems using them.


Happy sanding. :)


 

BPentz's picture

(post #78485, reply #37 of 40)

Brian,


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Wood dust varies greatly in terms of its toxicity and each of us have different tolerances. Before working with any wood or glued composite like MDF I highly recommend doing a search for wood toxicity and glue toxicity on Google then picking an information source that you are comfortable with. When working with any of the woods listed as highly toxic, I strongly recommend wearing a good form fitting, tight sealing dust mask with fine removable cartridge filters. With some, gloves and long sleeves are recommended. I personally try to capture the fine dust at its source and wear a good 3M half-mask when making fine dust and either leave that mask on for the next few hours or leave the shop afterward while my fans and air cleaner clear my shop air. A good automotive paint supplier fit my mask. You can get one from most hardware stores, but really should ensure a good fit that does not leak air. I also recommend a hat and jumper that get left in your shop to keep from tracking that fine dust into your car or home.


 


In addition to potential toxicity, we also know from the National Institute of Health that fine wood dust is identified from creating no symptoms to a wide variety of problems including a potential for the growth of polyps and cancer. I’m not a medical expert, so must defer to them. They say that the dust from sanding (hand or machine) is often sized in the 0 to 30 micron range, about 1/3 the thickness of a human hair. This size dust goes airborne in our shops and will stay airborne for hours even after all our tools, fans, etc. are shut down. They report this finest dust goes right past many of our natural protections and lodges deeply in our lungs and sinuses where our bodies have a very difficult time clearing that debris. They also say that over time a large number of professional woodworkers become disabled with respiratory related illnesses.


 


Most hobbyist air cleaners provide almost no protection from this fine dust for two reasons. First, you end up inhaling that dust for the hours it takes to clean your shop. Second, many of these units do not use fine enough filters certified to remove the 0 to 2 micron sized dust that many studies have identified as the most harmful with long term exposure.


 


Repeatedly responses to this thread and other dust related threads imply an assumption that is just plain dead wrong. Many assume that because they are hobbyists, they have a fraction of the exposure of professionals. In fact, most commercial concerns must meet air quality standards. Failure to meet those standards can result in fines and facility closure. There are no such standards for hobbyists. In fact, a friend who does air quality measurement for the State of California advises me that he has tested thousands of small shops where people converted their woodworking hobby into a profession then had to be tested as part of adding staff. He said consistently these shops, even with dust collectors and fine filter bags, test results regularly show over 10,000 times the legal concentrations for fine wood dust. He has also tested many hobbyist shops and found the same. As a result, hobbyists frequently get more fine wood dust exposure in four hours than a pro will in over six months. With no regulations or oversight it is up to each of us to decide how much risk we have, then decide on how to mitigate that risk.


 


I’ve tried hard to share not only the facts, but also solutions that will affordably help to collect that fine dust at its source. You can look at my Dust Collection Basics web page for more information.


 


Bill Pentz


Edited 2/29/2004 12:15:34 PM ET by bill pentz


Edited 2/29/2004 3:44:09 PM ET by bill pentz