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Fine Dust Properties

Fine dust poses a more serious hazard than most believe. Woodworking makes a huge amount of sawdust. About three pounds in every twenty is airborne dust that takes a while to settle. Roughly one pound in every twenty consists of fine particles that are invisible without magnification. Normal room air currents will launch and keep this fine dust airborne. This fine dust goes right through most “fine” filters and it gets right by our bodies’ natural protections. It lodges in our respiratory tissues where we have a difficult time getting rid of it. The medical research clearly shows every exposure to this fine inhalable dust causes a loss in respiratory capacity and some of this loss becomes permanent. 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. Most medical research and health insurance data are for workers in shops that vent 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.

This is really bad news for small shop workers because government air quality testing shows shops that vent inside average two to five times higher airborne dust levels than shops that vent outside. Worse, our filters pull off the larger particles and freely pass the fine invisible particles known to cause the most health problems. We make this 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. This fine dust takes a long time to break down and dissipate. Our venting inside traps and cycles this fine dust causing it to build to dangerously high levels. As a result, even hobbyists 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. The government allowed maximums are fifty times tougher for this fine dust. My respiratory doctor says small shop woodworkers should make fine dust collection a top priority because of our much higher exposures and our frequent use of far more toxic woods.

Risk Factors

Risks define what can happen. A good Wood Toxicity Table shows different woods contain chemicals that can be poisonous, cause irritation and infection, can cause us to sensitize with dangerously unhealthy allergic reactions, and increase our risk of cancer. 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. Fine airborne dust particles pose another far less understood long term risk. We are constantly exposed to lots of fine dust in our daily activities, but our bodies do a good job of eliminating most dust. A few dust sources are known to damage to our health due to their shape and particle composition. Fine wood dust particles depending upon particle size lodge in our tissues similar to the fiberglass particles that cause silicosis and asbestos particles that cause asbestosis leading eventually to chronic obstructive pulmonary disease (COPD). Fine wood dust can create life long problems with our airflow problems and allergic reactions.


Probability of Harm

We also need to know the odds of this happening to us to decide how much if any protections we want to provide. The damage caused by wood dust depends upon overall health, genetics, type of exposure, amount of exposure, frequency of exposure, and duration of exposure. Almost all medical studies that give the different probabilities of being harmed are studies of workers in large facilities that vent their fine dust away outside. These studies show about one in eight gets forced into an early wood dust related medical retirement. For those shops that vent outside and improve their dust collection ample to meet OSHA air quality standards the number forced into an early fine dust related medical retirement drops to one in fourteen. Government testing shows small shops that vent inside average two to five times higher dust levels by weight. Because we mostly use finer filters, the majority of this dust is made up of the fine invisible particles known to cause the most damage to our health. In fact, particle counts of the fine invisible dust for small shops that vent inside average thousands of times higher than shops that vent outside. As a result, even occasional small shop hobbyist woodworkers get more fine dust exposure in a few hours of woodworking that large shop professionals get in months. At these exposure rates all will get harmed.



·  Fine Dust Properties

Medical experts define fine dust as inhalable particles sized 10-microns and smaller which get by our natural protections and then get stuck in our tissues. We need magnification to see particles sized 10-microns and smaller, so these particles are invisible. A micron is one millionth of a meter. Human hair varies between about 40 to 100-microns thick. Government studies shows about 5% of the dust we make, which means one pound of every twenty is made up of fine invisible particles. Just two tiny thimblefuls of this fine dust will cause a large two-car garage sized shop to fail all of the different air quality tests. In other words we make pounds of fine dust yet a fraction of an ounce is enough to create dangerously unhealthy air quality. This fine dust is so light that gravity has little effect except in very still air. Just about any air movement is enough to launch and keep the invisible particles airborne. Once airborne these particles behave more like a gas or bad odor because they rapidly spread to evenly fill all available air. This dust takes a very long time to break down and dissipate, particularly in closed shops. Recall that the Introduction showed an electron microscope image of fine dust from one of the pyramids. Decades of air engineering have found that this fine dust spreads so quickly that once it escapes capture it is near impossible with exhaust fans and air cleaners to clean the air fast enough to keep from failing an air quality test.

Most small shop workers wrongly think that we are not at risk because we buy dust collection equipment with fine filters that leave us with clean looking shops.Having a clean looking shop is a bad false sense of security.Certain woods,like cocobolo, mahogany, maple, padauk, redwood, rosewood, sandalwood, teak, walnut, and western red cedar all were very strong sensitizers. Some of these like cocobolo and rosewood can create severe allergic reactions in just a few hours exposure. contaminated with more than double the airborne particles by weight that industrial hygienists recommend which is twenty times more than medical experts recommend. A microscope examination of the particles collected showed most were fine invisible wood dust particles that passed right through HVAC filters. exmainer’s particle counter showed most of that dust was blasted out of fine filter when the blower first got turned on. Twenty minutes of woodworking showed tools sprayed fine dust all over, impressive looking dust collection system did not collect most of the fine dust, and that fine filter was a sieve that let the fine dust pass right through. The airborne dust level climbed to over double the maximum allowed government standard which is over 100 times higher than considered safe by medical experts and the Environmental Protection Agency (EPA). The count of the fine invisible particles surged to over 10,000 times higher than considered medically safe. inspector said fine dust problem was caused by small shop vendor selling something that just plain did not work and posed a serious fire risk. area having a small shop dust collector or cyclone inside in a commercial shop would immediately fail a fire marshal or building inspector inspection. most small shop dust collectors and cyclones are such terrible “dust pumps” they should either be vented outside or not used at all. most woodworkers would be far safer to work with the garage door opened a little with a good exhaust fan blowing out the side door and wearing a good respirator mask when making fine dust.

Two tiny thimblefuls of this fine dust are enough to 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.