- Information Availability
- Good Shop Safety
- Carbon Monoxide Poisoning
- Fire & Explosion Safety
- Health Effects
- Wood Toxicity Table
This page shares fine dust risks and bad news for small shop workers. It presumes you have already read the Introduction and Dust Collection Basics pages. Wood at a microscopic view behaves like a huge stack of glued together fine glass tubes. Every time we touch wood with our blades, bits, cutters, or sandpaper these tubes shatter which launches millions of very fine particles airborne. These particles are so small they are invisible without magnification and so light they stay airborne to quickly spread to contaminate all shared air much like a bad odor. These fine particles are covered with razor sharp edges and sharp often barbed points that damage and scar our respiratory tissues. The medical research shows this damage is so high that the EPA sets really tough airborne dust limits. Woodworking makes too much fine dust compared to how little it takes to harm our health. OSHA testing shows with every twenty pounds of sawdust we also make enough fine invisible dust particles to cause over 15,000 typical two-car garage sized shops to fail an EPA air quality test. Worse, wood dusts also contain and carry toxic chemicals that cause other health problems. The insurance data only cover large facility woodworkers. These data show very few large facility woodworkers get poisoned or develop cancer, but one in seven develop such bad allergic reactions they must stop woodworking, one in fourteen is forced into an early medical retirement and almost all lose about 1% of their respiratory capacity per year of work. The respiratory damage is so slow most don't feel anything as it occurs, but the loss builds over time into serious problems and shortens lifespans. One of the better Internet overviews of the risks is printed by the United Kingdom government, Health & Safety Executive (HSE) in their Toxic Woods - Woodworking Sheet No. 30.
These health risks should terrify small shop woodworkers because we get much higher exposures and work more dangerous woods. Most large facilities vent their dust collection systems outside, so the finest unhealthiest dust gets blown away where it quickly biologically breaks down after it gets damp. Conversely, most small shop workers vent our dust collection inside where the fine dust stays dry enough to last decades. Add small shop dust collection systems missing on average about 15% of the fine dust and even most very clean looking shops build dangerously high invisible dust levels. OSHA testing shows just walking around without doing any woodworking in most small shops that vent inside stirs enough fine invisible dust airborne to fail EPA air quality tests. At typical small shop exposure rates most small shop workers get more fine dust exposure in a few hours woodworking than large facility workers get in months of full time work. The medical research clearly shows the higher and longer the exposure the greater the damage. Worse, small shop woodworkers frequently work more toxic woods, so our higher exposures are often to more toxic dusts. As you can see in the below Wood Toxicity Table many woods contain chemicals that can be poisonous, cause us to develop pneumonia, increase our risk of cancer, badly irritate our eyes, skin and respiratory systems, and are sensitizers meaning we build allergic reactions sometimes in as little as a few hours of exposure. My respiratory doctor provided a simple summary. He said most small shop woodworkers leave dust collection as one of our last priorities, but protecting ourselves and those close to us from fine wood dust should be one of our first because wood dust is so dangerous.
- Good Shop Safety
Before diving more into dust collection, first a few words on general shop safety. Although wood dust is dangerous, that does not mean you can ignore other good shop safety practices. There are too many ways that woodworking can hurt us through inattention, ignorance, and neglect. One of my favorite magazines, Fine Wood Working published by Taunton Press, includes the following caution in every magazine issue, "Working wood is inherently dangerous. Using hand or power tools improperly or ignoring standard safety practices can lead to permanent injury or even death. Don't try to perform operations you learn about here (or elsewhere) until you're certain that they are safe for you. If something about an operation does not feel right, don't do it. Look for another way. We want you to enjoy the craft, so please keep safety foremost in your mind whenever you're in the shop." Most agree with this warning because we can look at a powerful or sharp tool that cuts hard wood like soft butter and know we need to be careful.
For the most part, learning shop safety is fairly easy. I personally like the ABC approach, Always Be Careful, but being careful requires us to also be knowledgeable of the risks and proper usage. Our tools rarely come with good safety and usage instructions but there are lots of books, videos, classes, government publications, and Internet presentations that share how to safely use our tools. In my first woodworking classes in the fifties we were taught safely rules for every hand and power tool. We were required to use push sticks or power feeders whenever using a powered blade, bit, or cutter. We had yellow lines around each of the power tools that were no entry zones for all but the operator. We had red zones for potential kickback where even the operator should not go. We had a rule to immediately sweep up all sawdust to make sure that nobody got hurt from a slip. We even had a rule about putting sawdust and used rags only in sealed metal cans to prevent fires from spontaneous combustion. Likewise, we often use hazardous solvents, paints, varnishes, stains, glues, epoxies, fiberglass, acids, bleaches, solder, etc. Almost all of these come with good product information sheets giving the needed protections and cautions. Generally, we need to wear a good properly fitted cartridge filtered respirator mask and heavy rubber gloves then work outside or in a "clean room" with strong exhaust fan and hood. You can and should go to the library, use the Internet, and take classes to learn to use your tools safely. Frankly, little has changed since my father, a master woodworker, taught me that sweeping up right away made for a safer, more pleasant shop with less risk of fire or slipping near dangerous tools. The U.S. Department of Labor, Guide for Protecting Workers from Woodworking Hazards and the Health and Safety Executive web pages share many good woodworking safety practices and are recommended reading for all.
One of the first concerns with shop safety with wood dust is making sure that when you do woodworking that you avoid blasting yourself with a spray of sawdust and chips. As you will read shortly wood dust and the chemicals associated with wood can be very dangerous. This sprayed dust contains larger particles which can give us larger doses of these unhealthy chemicals. This sprayed dust can also give us splinters, coat our skin, get in our eyes, and load up our respiratory systems. This high dust exposure greatly increases our risks of developing irritation, infections, allergies, cancer, and long term respiratory system damage. Always work in such a way that dust streams are directed away from you and never get yourself in a position where you end up breathing a blast of dust. Unfortunately many tools make following this advice difficult. For instance, the normal spot to stand when using our table saws puts us right in the blast of dust that comes off our saw blades. As you will find in the following Dust Collection Basics pages, we need to upgrade almost all tool hoods to block, control, capture and deliver these blasts of dust.
- Carbon Monoxide Poisoning
Although woodworking creates little carbon monoxide, my respiratory doctor said woodworkers often suffer carbon monoxide poisoning. Burning wood, charcoal, coal, natural gas, propane, methane, gasoline, oil, and other fossil fuels creates carbon monoxide. Almost everyone has many carbon monoxide producing sources close by including our vehicles, furnaces, propane heaters, stoves, ovens, gas driers, BBQs, charcoal grills, water heaters, etc. Each comes with instructions to ensure their safe use. Unfortunately our dust collection can make these normally safe sources of carbon monoxide dangerous. Most small shop woodworkers do not realize our dust collectors, cyclones, blowers, and exhaust fans are so powerful that they often suck deadly carbon monoxide into our shops and homes backward through vents and flues from nearby normally safe carbon monoxide sources. This leaves us at high risk of severe short and long term carbon monoxide poisoning.
Carbon Monoxide is a colorless odorless poisonous gas. It prevents our red blood cells from carrying oxygen. The loss of oxygen shuts down our nervous systems similar to the effects of alcohol so we cannot tell when we are exposed until too late, so carbon monoxide kills thousands of people in the U.S. yearly, more than all other poisonings combined. How ill we get depends upon age, overall health, exposure amount, and exposure time. More serious carbon monoxide poisoning produces mild flu like symptoms that progressively worsen including drowsiness, exhaustion, headache, dizziness, changes in body temperature, changes in blood pressure, loss of appetite, pain in extremities, loss of coordination, nausea, vomiting, disorientation, difficulty breathing, irregular heartbeat, chest pain, visual disturbances, hallucinations, tremors, convulsions, suffocation, and coma. Unfortunately, up to 40% of those who suffer serious carbon monoxide poisoning and many who are exposed to lesser amounts for long periods, including small shop woodworkers, end up with permanent health damage. Often the initial symptoms become permanent plus many later develop eye damage, hearing loss, blood disorders, heart damage, nerve damage, numbness, brain damage, amnesia, memory loss, behavior changes, Parkinson like tremors, and birth defects. Clearly when things go wrong we cannot tell without a detector when we are breathing in carbon monoxide until too late. My doctor strongly recommends installing, using and maintaining carbon monoxide detectors in our homes and shops. I recommend that if you vent your dust collection outside that you also provide an opening to outside for makeup air that is at least twice the diameter of your ducting going outside. That makeup air will keep our equipment from sucking the fumes backward from our vents.
- Fire & Explosion Safety
Wood dust poses a moderate but serious explosion hazard. Fine wood and metal particles become very explosive when enough are mixed with air. The good news is most small shops make too little dust at one time and generate too little static electricity to trigger an explosion.
Wood dust poses a much more serious fire hazard. Most small shop fires occur when sparks, cigarettes, hot pieces of cut metal, etc. land in piles of sawdust on our floors, in our dust bins, our dust filled ducts or dust filled filters. The high airflow inside our dust collection systems can quickly cause a fire, or smoldering can go on for hours then break into a fire long after we leave our shops. Most small shop fires start in our dust piles and dust collection bins, so it is always a good idea to clean up dust piles and use metal bins that will contain any problems.
We get sparks and hot pieces of metal many different ways. We get static electricity sparks from a buildup of static at our machines, ducting, dust collection and filters. Unlike larger shops it is almost impossible for these electrical sparks to be powerful enough in small shops to trigger a fire or explosion. These static shocks can be very dangerous if we get hit when working close to fast moving blades, bits and cutters, so good static protection is a must particularly in cold dry weather. I was stunned to watch a video a friend of mine made using a table saw to cut hardwood in the dark. It looked like he was grinding a piece of steel as sparks flew off the blade all over. Our fast moving blades, bits and cutters create sparks when we work wood, especially knots and high silica content wood. Fortunately, these sparks are almost all so short lived they rarely could cause a fire. We get longer lived sparks if our tools hit staples, nails, screws or other pieces of metal. If these longer lived sparks land in a pile of sawdust, or dust piles in our ducts or filters the airflow can quickly create a nasty fire. This is why we should check suspect wood with a nail finder before processing. Metal pulled through our dust collection system can slam into metal duct and dust collection components hard enough to create sparks. We also get bad sparks that can fall into our dust bins when our fast moving blower impellers hit a piece of steel or aluminum. Most good big vacuum floor pickups have built in magnets to catch steel and iron bits before it gets sucked through our dust collection systems. Grinders and sanding on steel or aluminum makes sparks so you should never use these with vacuums or dust collection systems also used to collect wood or other flammable dust.
These fire dangers are why the National Fire Protection Association (NFPA) who writes the codes most fire marshals and building inspectors follow have lots of formal rules to prevent fires. Good work practices and most local codes require that floors, tools and work surfaces have ample dust collection to stay clear when in use. This helps avoid falls from slipping, lets us better see our work, keeps our blades, bits and cutters visible, and keeps sparks from landing in nearby piles of dust. The NFPA requires use of only metal duct in spite of many using PVC and other materials. At one time the NFPA only allowed aluminum blower impellers, but now NFPA recommends against aluminum impellers. When hit by a fast moving piece of steel aluminum launches large white hot sparks just like a sparkler. Our small shop vendors do us a double disservice with their current cyclones and dust collectors. Their plastic bag and cardboard dust collection bins will not contain a fire or ever pass fire marshal, building inspection, or insurance agent inspection. If we want extra insurance or to go professional and pass an inspection we have to buy new units. Worse, even with upgraded bins, these units are still not fire and explosion certified, so they have to be moved outside behind fire and explosion proof barriers. Specifically the NFPA Standard 664 "Prevention of Fires and Explosions in Wood Processing and Woodworking Facilities" Chapter 8, Woodworking Dust-Control Systems, Section 2.2 states, "Dust collectors shall be located outside of buildings." Two exceptions are listed which permit dust collectors to be located inside of buildings:
If they are located adjacent to an exterior wall, or vented to the outside through straight ducts not exceeding 10 feet (3 meters) in length, and have explosion vents.
If protected by an explosion suppression system meeting the requirements of NFPA 69, Standard on Explosion Prevention System.
Now as a practical matter most small shop woodworkers do put their dust collectors and cyclone separator systems indoors. Putting our dust collectors and cyclones inside greatly increases our risk of fire. Additionally, bringing our dust collectors and cyclones indoors often creates a bad false sense of security. We often end up with very clean looking shops that build dangerously high amounts of fine dust. When outside these units vent the fine invisible dust outside where it quickly dissipates. When vented indoors just walking through most very clean looking shops stirs up enough fine dust that we will fail an air quality test without doing any woodworking.
- Health Effects
What my father and decades of woodworking classes failed to share and what my respiratory doctor made me learn more about are the potentially dangerous health effects from working with wood, particularly fine invisible wood dust. Some health issues come from touching and handling larger pieces of wood but most come from contact with wood dust. What I knew from decades of experience, considerable instruction and reading was when working with some woods I needed to wear safety glasses and a good dual cartridge respirator mask to keep the dust out of my mouth, nose, and eyes plus always wash up after working. Not wanting to give up either my woodworking or lifetime collection of tools I used the Internet to further research the risks of fine dust and how to control it. With a forced three months of bed rest following my being hospitalized from my fine wood dust exposures I had lots of time to do that research.
Splinter wounds, cuts and eye injuries from a number of woods are slow to heal and often turn septic, e.g. greenheart, mansonia and redwood. This is partly due to the species involved and partly due to secondary infections from bacteria and fungi entering through the skin.
Some woods are poisonous or treated with chemicals that are poisonous, so enough contact or inhalation can cause illness, vomiting, neurological damage and even death. Lots of plants develop strong chemicals for protection from bugs and predators, plus keep away plants that would otherwise compete for food, water, and sunlight. Some of these chemicals are very poisonous and can create a variety of health problems including heart and chest pain, anemia which leaves our cells oxygen starved, kidney and liver disease. A number of woodworkers have had serious health problems from trying to work treated wood, insecticide covered wood, hemlock, mandrake root, mimosa, oleander, sassafras, yew, etc. with a few coming close to dying from trying to do woodworking such as making small pens and such from the stems of what look to be interesting bushes.
Many plants also contain chemicals which may not be outright poisonous but are strong irritants that can quickly make us feel miserable. Working with irritating woods can cause sneezing, coughing, conjunctivitis (watery or prickly eyes), rashes, dermatitis (dry itching and cracking skin), stomach upset and respiratory problems. Irritation can, in some species of wood, lead to nettle rashes or irritant dermatitis. These effects, from direct contact or cross-contamination to other parts of the body by hand, tend to appear on the forearm, backs of the hands, the face (particularly eyelids), neck, scalp and the genitals. On average, they take 15 days to develop. Symptoms usually only persist as long as the affected skin site remains in contact with the source of irritation such as the wood dust or sap etc. Symptoms subside when contact with the irritant is removed. All these can develop into other more serious problems such as chronic incurable runny noses, sinus infections, pneumonia and even hepatitis. Most of us know from bad experiences with poison oak and poison ivy that some of these chemicals can be nasty. Trimming oleander, yew and mimosa or working these woods can make us very sick and even kill us.
Many, actually most woods contain sensitizing agents that cause us to build up allergic reactions. Our bodies do a pretty good job of handling the mild sensitizers unless we have very long term or constant prolonged exposure such as from a contaminated home or office. Then, just like the stronger sensitizing woods, we can build dangerous allergic reactions. Some of these strongest common sensitizing woods are red cedar and walnut. These can build up strong allergic reactions in just a few exposures. Cocobolo and rosewood are such strong sensitizers that some have strong reactions after just a few hours exposure. How quickly we become sensitized depends upon the strength of the sensitizer, our amount of exposure, how long we are exposed, and our individual health. The resulting allergic reactions can vary from mild sore throat, headache, asthma, sinus pain and cold like symptoms, to chronic eye, ear, nose, sinus, throat and lung irritation which invariably leads to infections. If the exposures are allowed to continue the attacks can be potentially life threatening with anaphylactic shock where our airways close down and we can die without immediate medical help.
The more and larger particles we inhale the higher our exposures to some of the chemicals which are known to increase the risk of cancer. Fortunately, the risk is small, roughly 7 in 10,000 and most wood dust related cancers are in the mouth, nose, sinuses and throat where they can be treated successfully if caught early.
Additionally, there are some common diseases identified and associated with fine dust exposure, particularly wood dusts. Below is a copy of government information with descriptions of the major wood related illnesses
- Sensitization dermatitis
Sensitization dermatitis is more problematic and is usually caused by skin exposure to fine wood dust of certain species. Rashes can appear on skin well away from the original point of contact. This is also referred to as allergic contact dermatitis and results in similar skin effects to those produced by skin irritants. However, once sensitized the body sets up an allergic reaction and the skin may react severely if subsequently exposed to even very small amounts of the wood dust. Cross-sensitization may develop where other woods or even non-wood materials produce a similar response.
The primary long term disease risk from wood dust is fibrosis which comes from the long term damage from very fine dust particles. The U.S. Environmental Protection Agency (EPA) in their EPA PM2.5 NAAQS Implementation says fine dust particles sized 2.5-microns and smaller pose significant long term risks, "Health studies have shown a significant association between exposure to fine particles and premature mortality. Other important effects include aggravation of respiratory and cardiovascular disease (as indicated by increased hospital admissions, emergency room visits, absences from school or work, and restricted activity days), lung disease, decreased lung function, asthma attacks, and certain cardiovascular problems such as heart attacks and cardiac arrhythmia. Individuals particularly sensitive to fine particle exposure include older adults, people with heart and lung disease, and children."
The accumulation of fine wood dust in our airways and lungs creates long term problems similar to asbestos and fiberglass inhalation. A buildup of these fibers in our nose, sinus, throat, and lung tissue over time causes damage where our airways slowly close down from being filled with fibers and scar tissue. That makes sense because trees get much of their strength from silica better known as glass, plus wood is made up of the same kinds of fibers that cause these other problems. The medical research is clear there is no safe level of wood dust exposure because every fine wood dust exposure creates some measurable damage and some of this damage becomes permanent. The amount of damage depends upon our general health, how much we take in and for how long.
Enough exposure over time creates serious permanent damage. Like smoking, the changes are so slow most do not realize they are developing a problem until they become seriously ill. The insurance and medical research data show that most woodworkers will go ten or more years before becoming aware of any ill affects (just as many can smoke tobacco for years with no apparent ill affects). That applies to factory woodworkers who average two to five times less than small shop woodworkers. At small shop airborne dust exposure levels most will have enough damage eventually to adversely affect the quality of our lives with roughly one in eight ending up with such serious medical problems they are forced into early medical retirement.
- Dry rot HP
Dry rot HP (Hypersensitivity pneumonitis) is an acute and/or chronic condition with acute presentation: flu-like illness with cough; Subacute: recurrent "pneumonia"; Chronic: exertional dyspnea, productive cough, and weight loss; Most patients have abnormal imaging studies (chest x-ray or high-resolution CT). Crepitant rales are heard in some cases. Pulmonary function testing shows a restrictive defect in early disease and a restrictive, obstructive or mixed defect in late disease. Precipitating antibodies are neither sensitive nor specific, and their presence is no longer considered a hallmark of HP. Some patients have decreased diffusion capacity and arterial hypoxemia. If the diagnosis is in doubt, bronchoalveolar lavage (BAL) typically shows lymphocytosis. Surgical lung biopsy may be indicated if bronchoscopy is nondiagnostic. The disease latency varies from a few weeks to years after first exposure. Symptoms appear or worsen within a few hours of antigen exposure to bioaerosols of microbial or animal antigens or rarely to a few reactive chemicals. Complete recovery usually occurs if exposure is terminated early. Otherwise, the disease may progress to interstitial fibrosis. [Murray, p. 1783-1799]
- Organic dust inhalation fever
Organic dust inhalation fever is a moderate to acute condition with Symptoms: flu-like illness with cough preceded by eye and nasal irritation; Signs: leukocytosis; normal chest x-ray; Onset after exposure: 4-8 hours; Heavy exposure to: dusts from organic matter such as moldy hay, silage, compost, or wood chips; Resolution: within two to three days; Comments: As for other inhalation fevers, the treatment is supportive only.
Sequoiosis is a chronic condition with acute presentation: flu-like illness with cough; Subacute: recurrent "pneumonia"; Chronic: exertional dyspnea, productive cough, and weight loss; The exposure is to moldy wood dust, and the suspected antigen is the fungi, Graphium, Aureobasidium pullulans. [Harber, p. 202] See "Hypersensitivity pneumonitis, chronic" and "Hypersensitivity pneumonitis, acute."
- Tree cutter lung
Tree cutter lung is a chronic condition with acute presentation: flu-like illness with cough; Subacute: recurrent "pneumonia"; Chronic: exertional dyspnea, productive cough, and weight loss; The exposure is to wood chips from living maple and oak trees, and the suspected antigens are Penicillium (three species), Paecilomyces sp., Aspergillus niger, Aspergillus sp., and Rhizopus sp. [See Reference Link] See "Hypersensitivity pneumonitis, chronic" and "Hypersensitivity pneumonitis, acute."
- Wood trimmer lung
Wood trimmer lung is a chronic condition with acute presentation: flu-like illness with cough; Subacute: recurrent "pneumonia"; Chronic: exertional dyspnea, productive cough, and weight loss; The exposure is to moldy wood trimmings, and the suspected antigen is the fungus (Rhizopus species). [Harber, p. 202] See "Hypersensitivity pneumonitis, chronic" and "Hypersensitivity pneumonitis, acute."
- Sensitization dermatitis
- Wood Toxicity Table
The medical research makes it clear we should never work with woods that we don't know about their possible dangers. I looked for a thorough current list of the potential ill health effects from woods. Although there were many wood toxicity tables, most are copies of each other with a few minor changes and upgrades. Most of these charts and tables are based on work done by Roy Banner, a wood turner from Torrance, California who almost lost his life in 1989 to anaphylactic shock after turning pieces of exotic wood. One of the more current and complete wood toxicity tables can be found at HEALTH HAZARDS & WOOD shared by the Woodworking Australia web pages. I found that the existing charts date back mostly before 1990, so I did the research and built the more current below Wood Toxicity Table. This table provides a pretty good overview of the potential health effects from working with most readily available woods. Realize it is incomplete because many woods that are of relatively limited distribution have never been analyzed for toxins. Also, every woodworker may experience different reactions with different intensities, so please always wear a mask whenever working with any known toxic woods. I recommend you wear a good dual cartridge respirator mask any time you make fine dust and that you leave your mask on whenever in your shop until after you have thoroughly cleaned out your shop of all the fine residual dust. Our particle meters show to get rid of the fine dust we have to thoroughly blow out our shops while we run a strong fan blowing out a back door or window with a front main door open. That fan needs to stay on for about a half hour after blowing all off.
This Toxicity Table unfortunately does little to share the risks from the other chemicals that are frequently associated from woods and wood products that come from molds, fungi, yeasts, lichens, insecticides, herbicides, glues, resins, paints, solvents, binders, fillers, silicon, plastics, etc. which are also known to be harmful to our health. For instance, wood molds create some of the most toxic poisons known to man, which is why so many turners get very ill when they turn spalted wood (wood with mold lines).
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