Dust is bad for you but what do you do?

Fine wood dust is a serious hazard, especially if you have any respiratory problems. Even if you feel that dust does not bother you it can have a cumulative effect eventually resulting, if you are unlucky, in permanent damage to your health.

The problem for woodturners is that conventional dust extractors do not work too well for taking dust away from the lathe. It is easy to construct a casing around a bandsaw, for example, and connect the hose of a dust extractor so all the dust is whisked away. Unfortunately you cannot put an enclosure around the lathe because that would get in the way of you and your turning tools. You can try putting the air intake of the extractor as close behind the revolving wood as possible and if you have a really good airflow this will remove some of the dust.

However a lot of dust will inevitably escape. Even a powerful extractor will leave some fine dust hanging around for you to breath in. Try holding your finger close to the nozzle of a domestic vacuum cleaner or "wet & dry" workshop cleaner if you have one. You can feel strong air movement. Then try holding your finger four inches away - do you feel much happening? Try hoovering up some dust by holding the nozzle 4" off the floor and you will soon realize the extent of the problem.

So what is the answer? My recommendations are as follows . . .
	Step 1 Buy a respirator like the Trend Airshield. They are quiet, take up little space and give you better lung protection than any dust extractor machine. The polycarbonate face shield will also give vital impact protection.
Step 2 Buy a small dust extractor. Because you have the respirator to give primary protection you do not need a huge powerful machine. It will help to keep your workshop clean and you can use it with it's flexible hose to hoover up the shavings and remove dust which has settled on surfaces. Because you have a woodturning lathe you can quickly turn up a wooden adaptor to accept the hose from your domestic vacuum cleaner to give you a handy extension hose. If you have other woodworking machines such as a table saw you can hook up the extractor to them when you need to use them.
Step 3 To eliminate the problem with the fine dust hanging around in the air you could consider buying an air cleaner. These consist of a fairly quiet motor and fan with a fine filter which continuously removes fine suspended dust. They can be left on with a timer after you have finished work and they will eventually leave you with a workshop full of nice clean air. They will not protect you while you are working because they take a while to filter out the dust but they will considerably reduce the amount of fine stuff settling on surfaces.

Other precautions you can take to help.
Minimize the sanding. (Power sanding is particularly good at filling the air with dust). Use sharp tools and develop your skill to the point where very little sanding has to be done. Try using the wet sanding method which does not produce dust.
Try roughing out your bowls from green unseasoned wood. You can save a fortune on material and turning wet wood does not produce dust.
Wear a hat to keep dust out of your hair
When you leave the workshop leave your overall and your hat behind to save taking the dust into the house.

Dust extractor machines

There are two different designs used.
One type of machine uses a robust centrifugal fan to suck dust directly through the fan blades into bags which blow up like balloons when the motor is switched on. The lower bag collects most of the chips and can be plastic while the upper bag is cloth and acts as a filter. The fine dust soon cakes onto the inside surface of the bag and this layer of dust itself contributes to the efficiency of filtering. Large particles fall down into the lower bag. The lower bag must be emptied periodically, preferably before it fills up to the top. The better machines have a cyclone separator. This means that the incoming stream of dust and air is made to follow a corkscrew path inside the machine before it gets to the collector bags. The centrifugal force generated by the violent spinning motion makes the heavy chips and large dust particles fly to the outside of the airstream and fall down out of the way before they can clog the filter bag. There is a variation on this design which uses only one large hanging bag. With this machine the upper part of the bag does the filtering and the bag must never be allowed to fill right up. Almost all these external bag machines have induction motors which are more efficient and very much quieter than the other machines based on the "wet & dry" design principle. The external bag machines are generally better for woodturning lathes because they have a greater airflow.

The other type of machine works like a vacuum cleaner. The fan sucks the air into an oil drum shaped container and then through an internal filter. These machines usually also make use of the cyclone effect to reduce the load on the filter. This type of machine is cheaper, takes less space, has superior filtration and has a stronger suction for hoovering. The motor however is very noisy and the airflow is much less than the external bag machine. The small filters clog quickly reducing the airflow dramatically.

What woodturners really need is a machine which moves a larger volume of air at lower speed - a breeze which wafts the fine suspended dust away from the lathe into an efficient filter. The only systems commercially produced so far as I know which get anywhere near a solution are those setups for paint spraying and welding which consist of a large three sided box built around the work area. Built into the rear of the box is an array of huge powerful fans which suck all fine dust and fumes through suitably designed filters at the rear and recirculate the air. They work well because they move a very large volume of air. These are large and extremely expensive. It is time someone came up with a system specially for woodturners which hobbyists could afford.

More about dust hazards
The fine dust is the most dangerous and the most difficult to get rid of. The shavings and the large particles of dust are not much of a problem as most of it falls to the floor quickly and lungs have a built in mechanism which can eject relatively large particles. (If you smoke, the little hairs inside your lungs which do the work, may become damaged, so smokers are more vulnerable to wood dust.) Fine dust, however, hangs about in the air and if you breath it into the deepest parts of your lungs it can become trapped in there and cause all sorts of problems. The dust particles that cause damage are normally in the range of 0.2 to 5 microns in size (a micron is one thousandth of a millimetre) and are so small as to be invisible to the naked eye. They can remain suspended in the air for hours. Even if you cannot see any dust the atmosphere may still be harming your lungs. You are likely to breath 8 to 10 cubic metres of air during an 8 hour working day. If the dust in the air averages out to, say, 5mg per cubic metre during that period then you will suck in 50gm (2 ounces) of dust. Most of this will be dealt with by the body's own dust defence mechanism - the nasal hair and the mucus lined walls of the airways leading to the lungs. You will, in fact, swallow most of it. Only a very tiny percentage of the dust is permanently trapped in the lungs but it is this which causes the damage. 5mg/cubic metre is a very high concentration and is, in fact, the maximum exposure level allowed under the COSHH regulations. COSHH means "Control of substances hazardous to health regulations 1988". It applies to all businesses and self-employed persons. You would be wise to abide by its recommendations even if you are only a hobbyist. Dust from some wood can cause skin complaints such as dermatitis. You should avoid carrying dust out of the workshop on your clothes - leave your overalls in the workshop when you leave - wash your hands and hair frequently. Most species of wood including home grown timber can be harmful but some species (mainly tropical) are much worse. Avoid, if possible, mansonia, cherry mahogany, redwood, beech, South American boxwood, Western red cedar, satinwood. To give only a few examples, pine, afrormosia, mahogany, boxwood, chestnut, cedar, iroko, ebony, rosewoods, beech, ramin, walnut, larch, spruce, teak, padauk, yew, cherry and oak are known to cause dermatitis, conjunctivitis, rhinitis and asthma. So be warned!

Copyright 1991 Roy Child. HTML version Feb2004