Introduction
Table of Contents
(click on topic to go there)- Foreword
Innumerable people have asked over the years why continue to provide the research, time and money needed to keep up these Cyclone and Dust Collection Research web pages. The answer is simple. I don’t want to see other small shop users blindsided as I was.
- Introduction
Although cleanup of wood dust, shavings, curls and chips known as “chip collection” remains important to avoid fires, slipping, and being able to see as we work, I painfully discovered a dangerous hidden fine dust hazard. Most small shop workers wrongly think we get minimal dust exposure. Frankly our vendors have long lied to us saying woodworking creates very little fine invisible dust when the reality is woodworking generates about one pound of fine invisible dust out of every twenty pounds of sawdust we make. Many foolishly believe that working with hand tools do not realize that even making a very clean long shaving with a hand plane generates considerable fine invisible dust. Most foolishly believe vendor hype and think we are well protected because we use finer bag and cartridge filters on our dust collectors and cyclones. Sadly, our dust collector and cyclone separator fine filters almost all fail to pull in the air needed to capture the fine dust as it is made, plus almost all small shop vendors sell fine filters that when tested with indoor standards only separate about one twentieth as well as they advertise. That means these units fail to collect and pump right through the long lasting fine invisible dust that causes the most damage to our health.
I learned this the hard way. I used the top magazine rated cyclone based dust collector with vendor designed and supplied ducting plus vendor recommended upgraded filter. That system left a clean looking shop that created a bad false sense of security. I landed me in the hospital from a bad wood dust triggered allergic reaction. Three months later certified air quality testing found the fine wood dust particle counts in my shop and home thousands of times higher than the EPA considers safe. With inexpensive particle meters now readily available thousands of woodworkers all over the world see that when we vent our dust collectors and cyclones inside we build up dangerously high amounts of fine invisible dust. Unless we vent our shops outside this invisible dust builds to such levels that just walking around in our shops without making any more dust stirs up enough previously made residual dust that our shops badly fail their air quality tests with thousands of times more fine airborne particles than found in commercial facilities that vent outside. A couple of hours working in a shop that vents its dust collection inside generates more fine dust exposure than a worker in a commercial shop that vents outside receives in months working full time. Because this fine dust behaves like a gas and spreads into any connected airspace almost all homes over basement shops and homes connected to garage based shops also test with dangerously high airborne dust levels. After decades of taking care of woodworkers and our family members for wood dust generated health problems often worsened by our using fairly toxic woods my respiratory doctor says small shop workers should make fine dust collection a top priority.- Fine Dust Properties
Medical experts define fine dust as inhalable particles sized 10-microns and smaller. A micron is one millionth of a meter and a meter is about 39” long. The picture on the left shows an average human hair of about 70-microns thick compared to 10-micron dust particles. We need magnification to see particles sized 10-microns and smaller, so fine dust particles remain invisible. Fine dust causes so many health problems that researchers and health experts study these fine particles so extensively that they generally abbreviate fine dust as PM short for particulate material. Researchers use PM-10 as shorthand for particles sized smaller than 10 microns, PM-5 for particles sized under 5-microns and PM-2.5 for particles sized under 2.5-microns.
Government studies show fine dust makes up one pound of every twenty, roughly 5% of the woodworking dust we make. Fine wood dust remains so light that normal room air currents overcome the effect of gravity and keep this dust airborne except in very still air. Just about any air movement will re-launch and keep fine wood dust particles airborne. Fine wood dust behaves similar to a gas or bad odor because it rapidly spreads to evenly fill all available air. This means basement and in-home shops can and often do badly contaminate the rest of our homes. Fine dust also readily travels in our hair, on our skin and on our clothes, so as woodworkers we often contaminate our homes, offices, vehicles, and other areas we visit when still wearing our shop clothes. Wood gets much of its strength from silica better known as glass or sand, so wood dust takes a very long time to break down and dissipate. These pages show pictures of wood dust that was found when sealed pyramids were opened, so thinking this dust simply breaksdown and vanishes quickly is pretty wishful thinking. So, once we have a wood dust contamination problem that problem stays with us until we do a thorough cleanup.- Risks
Risks define what can happen and fine dust poses many risks. We are constantly exposed to considerable fine dust in our daily activities, but our bodies do a good job of eliminating larger dust particles. Unfortunately, fine airborne dust particles get right by our natural protections. The sharp often barbed fine wood dust particles cut and tear then jam lodged in our tissues to reduce our airflow and cause scaring. As a result the medical research clearly shows every exposure to fine inhalable wood dust causes a loss in respiratory capacity and some of this loss becomes permanent. Over time this damage builds into chronic obstructive pulmonary disease (COPD) meaning our lungs get so damaged we cannot breathe well.
Trapped wood dust particles also contain toxic chemicals. We should always check a good wood toxicity table before using any wood because the dust we inhale can contain chemicals which are poisonous, strong irritants, sensitizers meaning they cause us to build ever stronger allergic reactions, and can increase our risk of cancer. Also, wood dust often carries many other chemicals from glues, finishes, fillers, insecticides, preservatives, molds, yeasts, mildews, etc. that can be present without our knowledge and can harm our health.- Probability of Harm
We need to know the odds of anything happening to us to decide how much if any protections we want to provide. The damage caused by fine dust depends upon overall health, genetics, type of exposure, amount of exposure, frequency of exposure, and duration of exposure. The higher, longer and more frequent our exposure the greater the harm. Doctors call this a dose response relationship. Almost all medical studies that give the different probabilities of harm studied health insurance data for woodworkers in large facilities that vent their fine dust away outside. The health insurance data show at typical exposure levels for shops that vent outside 100% of workers develop a significant loss in respiratory volume, about 14% are forced into an early dust related medical retirement, about 7% develop such bad sensitivity (allergies) that they must permanently give up woodworking, and about half of one percent develop dust related cancer. For the large facilities that voluntarily met the Department of Labor, Office of Safety and Health Administration (OSHA) recommended air quality standards the number forced into an early fine dust related medical retirement drops to about half, meaning one in seven is forced into an early dust related medical retirement.
This is really bad news for small shop workers because we average much higher exposures. We make the unhealthiest invisible fine dust by the pound, yet only a couple of small thimblefuls of are enough to cause a large two-car garage sized shop to fail all of the different air quality tests. Almost all small shop dust collectors and cyclones move too little air as established by decades of experience as the minimum needed for good fine dust collection. Likewise, those firms that guarantee customer air quality long ago found almost all stationary tools need their hoods upgraded to better control, trap and capture the fine dust as it gets made. Without ample airflow and upgraded hoods much of the considerable fine dust made in small shops escapes collection. Worse, our small shop vendors sell outdoor filters that need a year or more to build up to their advertised fine dust filtering level, so in the interim as these filters “season” meaning build up a cake of dust in the filter our so called fine bag and cartridge filters simply pull off the visible particles while pumping the fine unhealthiest invisible particles right through. This poor collection and filtering explains why government air quality tests show that in spite of making far less dust almost all small shops that vent inside end up with terrible airborne dust levels. Our small shops average two to five times higher airborne dust levels by weight with particle counts of the unhealthiest particles thousands of times higher than shops that vent outside. Because this fine dust lasts a very long time we also rapidly build a serious fine invisible residual dust problem where just about any activity including just walking around in our shops will launch the unhealthiest invisible residual dust particles airborne again and again. As a result, even hobbyist who do little woodworking often end up with a higher dust exposure in a few hours work than a full time large facility professional woodworker gets in months. Although we found no medical studies run on small shop workers, my respiratory physician said his experience from decades of practice convinces him that small shop workers, hobbyists, our families and even our pets often suffer the most and worst fine dust triggered health problems.- Issue
Although politics blocked enforcement of the 1998 OSHA air quality standard, other concerned organizations recommend much tougher standards for commercial woodworking shops. The American Council of Governmental Industrial Hygienists (AGGIH) recommends an air quality standard five times tougher than OSHA. Medical experts consider both the OSHA and ACGIH standards far too low. They recommend a standard that is fifty times tougher than OSHA. The European Union agreed and the Environmental Protection Agency (EPA) agree. Both set standards at about fifty times the OSHA standard. So how do we make repair to amply protect ourselves?
- Repair
Most incorrectly think we can eliminate our fine dust problems by wearing a good dual cartridge filtered mask like the 3M 7500 series whenever we make fine dust. A good respirator mask like this is a must because some shop activities create more dust than we can control. Others, including me at one time, foolishly believe that if we buy and install a good dust collector or cyclone with fine filters that we will end up well protected. Likewise, a good dust collector or cyclone also helps, but we still need to do more things to ensure we do not contaminate our offices, homes, and vehicles. To understand well enough to get our fine dust controlled we need to know a little more about dust collection. Here are some of the reasons why good fine dust collection poses more difficulty and expense than getting good “chip collection” which collects the same dust we sweep up with a broom.
National Fire Protection Association (NFPA) rules require collecting the heavier sawdust, chips, shavings, and wood strings that fall to our floors and work surfaces. Many experts call collecting this fallen material that we would otherwise sweep up with a broom “chip collection”. Most small shop dust collectors, cyclones, and vacuums only do chip collection. Likewise most tools either have no built in dust collection or come with hoods that only provide good chip collection.
Because of the high silica (glass meaning sand) content fine dust takes a very long time to breakdown. The picture to the right shows an electron microscope image of wood dust found in one of the pyramids when it was first unsealed after thousands of years.
Roughly three pounds out of every twenty pounds of sawdust we make consists of airborne dust. By definition airborne wood dust consists of particles sized 30-microns and smaller. Airborne dust when vented outside settles slowly enough in typical outdoor breezes that it dissipates without a trace. About three pounds in every twenty is airborne dust. The visible airborne dust particles settle in normal room air currents. These visible airborne dust particles ruin freshly painted finishes. Air cleaners address these larger visible airborne particles and do a good job of protecting our finishes. Unfortunately, few air cleaners move ample air or provide ample fine filtering to also protect our health.
About one third of the airborne dust consists of invisible dust particles known as fine dust. This means roughly one pound in every twenty pounds of sawdust we make consists of fine dust. Fine wood dust particles are smaller than 10-microns so they are invisible without magnification and rarely affect our finishing efforts. Unfortunately, these fine invisible dust particles go right past our bodies’ normal protections and cause the most harm to our health. The different sized invisible fine dust particles cause problems in different areas of our respiratory systems as shown in the above particle distribution graphic.
Woodworking makes lots of fine invisible dust even when using hand tools. To better understand think of wood as made up thin glass tubes lightly glued together. When we make that near perfect long shaving with our razor sharp hand plane at a microscopic level we actually drive a sharp steel wedge slashing through these glass tubes. The cutting shatters and launches all kinds of tiny airborne shards such as the particles shown on the electron microscope picture on the right. Many have written that their sensitive particle counters show almost every hand tool and other woodworking operation generates lots of fine dust even when we produce little or no larger sawdust particles.
Normal room air currents will keep fine dust airborne and these same air currents will launch previously made fine dust airborne repeatedly.
The fine dust takes a very long time to dissipate, particularly in closed shops.
Electron microscope images show fine wood dust with the same long sharp often barbed shapes found with asbestos and fiberglass which cause asbestosis and silicosis.
Although we make fine dust by the pound just two tiny thimblefuls of fine dust cause a large two-car garage sized shop to fail all of the different air quality tests both by weight and particle counts. We can launch this much fine dust by beating our shop apron.
Our tools lack the hoods needed to contain and control the faster moving air streams so they spray the fine dust away and miss collecting much of the fine dust.
Our dust collectors and cyclones move too little air to provide good fine dust collection. We all know when we put on vacuum hose on the blow port we can blow dust all over but that same hose when sucking will only pickup next to the nozzle. Air pulled by a vacuum comes from all directions at once so airspeed drops off at many times the distance squared. In short, our vacuum lacks the incoming air speed needed to pickup except very close to the nozzle. The same is true for fine dust as normal room air currents will blow the fine dust away unless we move a huge volume of air right around the working areas of our tools. Those commercial firms that guarantee customer air quality long ago through careful testing and decades of experience developed tables that show exactly how much air we need to move near each of our stationary tools. They found most small shop stationary tools need about 1000 cubic feet per minute (CFM) of airflow to have good fine dust collection and only need about 350 CFM for good “chip collection”. When we add the overhead resistance of our hoods, flex hose, ducting, and filters almost all dust collectors under 3 hp and cyclones under 3.5 hp fail to move this needed 1000 CFM.
Air at typical dust collection pressures will hardly compress so duct diameter and resistance sets maximum airflow at a given pressure. Most of our ducting and tool ports are too small to carry the needed air volumes.
The more air a blower moves the more power or amperage that the blower motor uses. If we shut off the airflow our blowers idle using the least power. If we open all up wide then our blower draws the most power. Dust collector blowers must overcome the resistance of our tool hoods, flex hose, ducting, and filters. Cyclone blowers must also overcome the high resistance from a cyclone forcing air to turn in a tight separation spiral. To overcome this resistance vendors use larger diameter impellers to create more pressure. It takes careful engineering to balance impeller size and resistance to get maximum motor performance without moving so much air the motor overloads and burns up. The top magazine rated dust collector vendor puts a warning on their dust collectors that they will burn up if run without at least 10’ of flex hose attached. All other major small shop dust collector vendors instead use a combination of small impellers and tiny ports to ensure that their motors do not burn up if a hose gets knocked loose and their blower runs with maximum airflow.
All of the major brand name dust collector and cyclone vendors remain caught in a nasty game of their own making. To appear better than their competitors each badly exaggerates their advertized airflow, filtering and separation. Plus these vendors fail to spend the tiny amounts needed to ensure the workability of their dust collection products. Sadly, our testing badly upset the small shop vendors.
We found only the Jet and Powermatic brands actually advertised airflows that we could get during our testing. All others advertised airflows that were far larger than we could get during testing. A few of the lesser quality imports exaggerated their airflows by as much as 100%.
We found all small shop vendors provide misleading airflow advertising. Almost all small shop vendors advertise maximum airflow which moves enough air for good fine dust collection. Maximum airflow only happens when we have no ducting, no filter or a brand new clean very open filter, and a special test pipe. This means that the advertised maximum airflows are just over double what we get in real use when our systems have to overcome the normal resistance from our hoods, ducting, separators, and filters.
The few firms that share airflow curves falsify their system performance through testing tricks which they convinced magazine editors to continue. Most of the magazine tests measure airflow with no ducting, no filter or a brand new clean very open filter, a special test pipe and oversized ducting much larger than we would use. These changes minimize resistance so the vendors can advertise higher airflow numbers. I reviewed one magazine test and helped conduct another. It sickened me to find that the winning dust collector vendor used an oversized impeller that will make their dust collector burn up if a hose gets knocked loose. With a standard test pipe this winning dust collector overheated and burned up its motor in about twelve minutes of operation. No collectors burned up during that test because it normally only takes about three minutes to do the air volume tests on a dust collector. Likewise, the top rated cyclone vendor demanded that we test their two, three and five hp cyclones with a significantly oversized test pipes. We found all of their motors rapidly overheated from pulling far more than their rated amps and three of their supplied cyclones burned up because these tests take longer to run. When we stopped our testing because the motors reached their maximum rated amperage, all previously top rated dust collector and cyclone vendors except Jet and Powermatic (both part of WMH Tools) lost their top ranking status. In short, running the top rated dust collectors and cyclones at their advertised airflows causes those motors to burn up within minutes.
In spite of the exaggerations, citing maximum airflows and testing tricks all major brand name small shop dust collectors and cyclones sized over 1.5 hp provided the 350 cubic feet per minute (CFM) needed for good chip collection but no dust collector under 3 hp or cyclone under 3.5 hp provided the 1000 CFM airflow that our vendors who guarantee air quality established that we need for good fine dust collection.
Likewise, our small shop vendors consistently advertise improper filtering levels. The American Society of Heating Refrigeration and Air-conditioning Engineers (ASHRAE) set the U.S. standards for indoor filters. As a filter gets used particles get trapped in the filter material that do not come out with normal automated cleaning. This is called seasoning. These particles build until a filter gets saturated and will take in no more particles. Manufactures call this a fully seasoned filter. A fully seasoned filter provides about twenty times better fine filtering than a clean new filter. Because it can take months to years for a filter to fully season, to amply protect our health ASHRAE requires that all filters for indoor use get rated when clean and new. Filter material makers share this clean new filtering level so engineers can comply with the ASHRAE standard for indoor air quality. Filter makers also provide the airflow and filtering levels for fully seasoned filters so air engineers can properly size outdoor filters.
Our small shop vendors claim that shops and garages represent outdoor rather than indoor use so advertise outdoor filtering levels, yet deliver equipment that can only be used in covered indoor areas. This combination makes for dangerously high indoor counts of the unhealthiest invisible particles freely passed by the more open filters even in clean looking shops.Almost all small shop vendors sell much smaller filters than filter makers recommend which depends upon airflow and dust loading. This results in our filters constantly needing cleaning which kills our needed airflow and over cleaning quickly ruins fine filters. The typical small shop dust collector or cyclone vendor generally provides about one square foot of filter material for every ten cubic feet per minute (CFM) of airflow. This is the normal for a 30-micron filter that lets the airborne dust blow away outdoors. Sadly, most vendors now sell 10 and 20-micron filters that they claim as either 0.5 or 1-micron filters and size them the same. The actual sizing according to the top filter makers should be at least one square foot of 0.5 or 1-micron fine filter material for every two CFM of airflow. This means a typical 1.5 hp dust collector with a maximum airflow of 1100 CFM and real airflow of about 550 CFM needs at least 275 square feet of fine filter area if we use a real fine filter. Rather than provide this much expensive fine filter material, most small shop vendors instead provide roughly thirty square feet of far more open filter material. The more open filters appear to work just as well as they filter off the visible dust but they freely pass the invisible dust. This makes for terrible air quality but avoids the upset of customers having to constantly clean and replace fine filters.
During the one to three years it takes a small shop filter to fully season the filter freely passes the fine unhealthiest dust leaving our lungs to do the fine filtering. Although some vendors claim much faster seasoning, the truth is seasoned filters provide little health protection. Every time a seasoned filter gets hit with a blast of air from starting our blowers it sprays dangerously high amounts of fine dust into our shop air. Likewise, after every thorough cleaning these too open filters freely pass the fine unhealthiest invisible dust.
Worse, most filters contain large amounts of polymer materials that build up large amounts of static as we run air through the filters. This static charge causes lots of the fine airborne dust to build and collect on the filter exterior surface then get blown all over our shops when we turn on our dust collectors or cyclones.
In summary we did not find one single small shop dust collector or cyclone with advertised fine filter that did not freely pass through a majority of the finest invisible unhealthiest dust.We also tested the separation ability of the various dust collectors and cyclones. As a baseline we first tested the two most popular trashcan separator lids. These trashcan separator lids work well and separate off almost all but the airborne dust. This means they captured about 85% of the dust created by weight and sent that remaining 15% airborne dust into the filters saving lots of time and trouble emptying dust bags and collection bins. When we stepped up the airflow from the 350 CFM needed for good chip collection to the 1000 CFM needed for good fine dust collection the trashcan separator lids became useless. The additional airflow scoured the cans clean of all but larger blocks and chunks.
At 350 CFM all but one small shop cyclone separated almost identically well as the trashcan separator lids. That one cyclone was so dismal that it put close to one third of the material it collected right into its filters. I had that firm identified on these pages and was quickly hit with a threat of a law suit demanding I remove that information. They did not care about how well their product works, only that nobody know how bad it works. They made no effort to improve this product and it continues to be sold exactly as was still being advertised as one of the best and most efficient. The magazine tests also found this one unit dismal and gave it their lowest possible rating without outright saying it was dismal. In defense of the magazines they do get considerable revenue from this vendor.
All other small shop cyclones except for my design separated little better than the trashcan separator lids. The only real advantage of these cyclones is at higher airflows than needed for “chip collection” all these cyclones continued to provide the same separation meaning close to 100% of the airborne dust went right into the filters. Independent medical school testing on my cyclone design found the same results as our testing. Instead of passing close to 100% of the airborne dust right through my cyclone design separates much better. It separates off over 82% of the airborne dust that other cyclones pass right through, plus it provides 99.9% separation of the unhealthiest invisible dust down to 4.7-microns. At this level of separation typical fine filters can go months instead of minutes between cleanings and these fine filters we need to amply protect our health will last years instead of the typical three months.Unlike air from a compressor or vacuum cleaner, at typical dust collection pressures air is little more compressible than water, so just about any tiny opening, small hose, small duct, rough duct, poorly made fitting, or bad ducting design will seriously harm the airflow we need for good fine dust collection. We found every small shop vendor who offered a ducting design service used professional shop ducting designs that presume no blast gates and full time collection from all machines at the same time. Because air at typical dust collection pressures will not compress, this requires that each main and branch be sized large enough to carry all air coming from downstream. This creates very impressive graduated ducting designs which work terribly in small shops that only use one machine at a time. The oversized mains end up with too little airspeed to keep from building up piles and plugging.
The fine invisible fugitive dust we miss collecting just keeps building in shops that vent inside. Almost any airflow is enough to launch this dust airborne and keep it airborne as long as we are working.
- Summary
In summary, the fittings, attachments, flex hose, ducting, fine filters, dust collectors and cyclones we buy to protect our health that do such a good job of chip collection create a bad false sense of security. These components that almost all sell leave us with clean looking shops while they actually turn our dust collectors and cyclones into dangerous “dust pumps” when vented inside. Using this equipment builds such dangerously high levels of fine invisible airborne dust that gets stirred airborne again and again even when we are not making more fine dust. These factors combine enough that small shop workers and even hobbyists that do minimal woodworking get more fine dust exposure in a couple of hours than those in facilities that vent outside get in months.
Click here for: Dust Collection Basics 
- Introduction
