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Dust – Medical Issues

A.    Overview

This information shares more detail on the risks of fine dust and presumes you have already read the Introduction and Dust Collection Basics sections. This Medical Risk section shares why fine airborne dust is doubly bad news for small shop woodworkers. First, testing by the State of California shows small shops that vent their dust collection inside average two to five times higher dust levels than large commercial woodworking facilities that vent outside. Second, small shop woodworkers frequently work with much more toxic woods than are processed in large facilities. As you can see in the below Wood Toxicity Table many woods contain chemicals that can be poisonous, strong irritants, sensitizers meaning they cause us to build allergic reactions, and can increase our risk of cancer.

Since I originally prepared this information a few good overviews have shown up on the Internet that cover the major health risks. You might want to look over this information as well. One of the better summaries of the risks is printed by the United Kingdom government, Health & Safety Executive (HSE) in their Toxic Woods – Woodworking Sheet No. 30. Another good quick overview article on Wood Toxicity was written by Barb Siddiqui for the “Women in Woodworking” web pages.

B.     Information Availability

Access to the information to make an informed decision is rapidly vanishing. When I started this work in 1999 the various health care insurance companies as a public service shared their data and summary information as did many universities, professional organizations, and governmental agencies. Today most only find a confusion of mostly second hand information. The once freely published standards from the various professional organizations are now prohibitively expensive for typical small shop woodworkers. The freely shared testing and medical study results are now mostly also charge items. The huge amounts of insurance data shared on the Internet vanished. My follow up calls to the main medical insurance companies were met with diversions. I called a friend who manages one of the larger health care insurance firms and he was pretty blunt. The insurance firms set their rates to provide the needed services and still show a profit. If people are healthier they can lower rates, so they freely shared data that showed all kinds of behaviors that have clear long term negative effects on our health and life spans. Wood dust is just one of many things they know has a big long term effect on the cost of providing health care, particularly in the later years. Although this sharing seemed well and good, in many areas it suddenly provided the fuel to create potential untold liability damage to those firms paying the medical insurance premiums. The medical insurance companies chose to stop the sharing rather than lose the firms paying the premiums. With the 2000 U.S. census showing woodworking is the fourth largest employer it is no wonder that private and government efforts to make repair are being done very quietly and carefully.

This leaves a confused mess of contradictory information. The large woodworking concerns have flooded the Internet with very authoritative studies often from prestigious universities that counter just about every aspect of there being any real short or long term danger from exposure to fine wood dust. Small shop woodworkers have to guess from what appear to be equally authoritative sources saying woodworking dust is dangerously unhealthy, others saying this dust is modestly unhealthy, and others saying woodworking makes no fine dust and there are no short or long term risks from fine dust exposure. With the worst dust being invisible and until recently the equipment to do our own testing was prohibitively expensive leaving most small shop workers guessing what information is accurate, then based on our guesses try to provide ample protection.

Complicating this mess even more are our small shop vendors. The competition to be the vendor of choice in this rapidly expanding market is beyond fierce. With almost all knowing little about dust collection including most of the vendors, what happened is these vendors copied and downsized traditional large facility dust collectors and cyclones. The original equipment was carefully engineered for outdoor use with cyclones designed to separate off the heavier chips and sawdust then blow the fine dust away outside where it quickly dissipates. Likewise dust collectors came with open filters that also passed this same fine dust to blow away outside. In copying and downsizing this equipment the small shop vendors did so without any concern about it being illegal in almost all areas to use this equipment inside in facilities subject to fire marshal inspection due to fire and explosion risks. These downsized dust collectors and cyclones vented 100% of the fine airborne dust inside building huge amounts of fine dust that coated everything. When too many began getting ill from this high dust exposure a few firms started making good money by selling finer filters. Although these finer filters get rid of the visible dust they create a bad false sense of security because they mostly freely pass the finest unhealthiest invisible dust. These filters are mounted on dust collectors and cyclones that do not move enough air for good collection and most of these units are plumbed with ducting far too small to carry the needed airflow.

The only real oversight on our small shop vendors is what we exercise with our buying decisions. Finding the time to gather the information needed to make informed purchasing decisions is tough and only made more difficult by our vendors. Most tend to rely upon the magazines they trust and word of mouth mostly through the Internet forums. What most do not realize is the main vendors pay not only for the magazines, they also provide most of the support including the salaries for the moderators on even the vendor free forums, plus these vendors pay both moderators and more established posters to recommend their products. As a result, much of the advice we get is directly from the vendors. They are focused on selling equipment and continue to push the positive traits of what they have to sell while ignoring the negative. Frankly, neither dust collectors nor cyclones have evolved much at all since 1999. They still almost all move far too little air, provide little better separation than a $25 trashcan separator lid, and cause small shops to create fine invisible airborne dust levels far worse than if we worked with a door open and exhaust fan blowing outside.

C.    Good Shop Safety

Before diving more into dust collection, first a few words on general shop safety. Worrying about airborne fine wood dust that often takes years to become a health concern does not make sense unless we start by first exercising 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 (Click here) and the Health and Safety Executive (Click here) 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.

D.    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 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. Carbon monoxide keeps 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.

E.     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. 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.

The medical research made it pretty clear that we should never work with woods that we don’t know about their possible dangers. That made one of my first concerns putting together a more current list of the potential ill health effects from woods. Although there were many wood toxicity tables on the Internet and in our small shop woodworking literature, 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 took the trouble to build a more current Wood Toxicity Table (click here). Realize that many woods that are of relatively limited distribution have never been analyzed for toxins and every woodworker may experience different reactions, so please always wear a mask whenever working with exotic woods. Also, keep that mask on any time in your shop until after you have thoroughly cleaned out your shop of all the fine residual dust that is so easily again launched and kept airborne.

This Toxicity Table provides a pretty good overview of the potential health effects from working with various woods. This 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, binders, fillers, silicon, plastics, etc. which are also known to be harmful to our health. To summarize this table says some woods and the chemicals associated with wood have the following effects.

1.      Poisons

Some woods are poisonous or treated with chemicals that are poisonous, so enough contact or inhalation can cause illness, 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 poisonous. 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.

2.      Irritants

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, watering eyes, rashes, stomach upset and respiratory problems that can develop into pneumonia and other more serious problems. Most of us know first hand from bad experiences with poison oak and poison ivy that some of these chemicals can be nasty. A few learn that oleanders can be so poisonous that just trimming these bushes can make us sick.

3.      Sensitizers

Many woods contain sensitizing agents that cause us to build up allergic reactions over time. Our bodies do a pretty good job of handling the mild sensitizers, but we can rapidly build up dangerous allergic reactions when exposed to some of the stronger sensitizing woods. Some of these strongest common wood sensitizers are red cedar, walnut, cocobolo and rosewood. These woods can build up very strong sensitization some times in just a few exposures. 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, 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.

4.      Carcinogens

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.

5.      Diseases

Unfortunately, this toxicity table also omits some of the common diseases identified and associated with woodworking. Below is a copy of information from the U.S. government with descriptions of the major wood related illnesses

a.     Fibrosis

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 an early medical retirement.

b.    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]

c.      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.

d.    Sequoiosis

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.”

e.      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.”

f.      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.”

F.     Doctor’s Summary

My respiratory doctor helped with his own summary. He said most small shop woodworkers leave dust collection as one of our last priorities, but protecting ourselves from fine wood dust should be one of our first because wood dust is so dangerous.


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