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Sawdust (or wood dust) is a by-product or waste product of
woodworking Woodworking is the skill of making items from wood, and includes cabinet making (cabinetry and furniture), wood carving, woodworking joints, joinery, carpentry, and woodturning. History Along with Rock (geology), stone, clay and animal parts, ...
operations such as
sawing A saw is a tool consisting of a tough blade, Wire saw, wire, or Chain saw, chain with a hard toothed edge. It is used to cut through material, very often wood though sometimes metal or stone. The cut is made by placing the toothed edge against t ...

sawing
,
sanding Sandpaper and glasspaper are names used for a type of coated abrasive that consists of sheets of paper or cloth with abrasive material glued to one face. Despite the use of the names neither sand nor glass are now used in the manufacture of these ...

sanding
,
milling Milling may refer to: * Milling (grinding), breaking solid materials into smaller pieces by grinding, crushing, or cutting in a mill * Milling (machining), a process of using rotary cutters to remove material from a workpiece * Milling (military tra ...
,
planing
planing
, and
routing Routing is the process of selecting a path for traffic in a Network theory, network or between or across multiple networks. Broadly, routing is performed in many types of networks, including circuit switching, circuit-switched networks, such as ...
. It is composed of small chippings of
wood Wood is a porous and fibrous structural tissue found in the stems and roots of tree In botany, a tree is a perennial plant with an elongated Plant stem, stem, or trunk (botany), trunk, supporting branches and leaves in most species. ...

wood
. These operations can be performed by
woodworking machine A Woodworking machine is a machine A machine is a man-made device that uses power to apply forces and control movement to perform an action. Machines can be driven by animals and people A people is a plurality of person A person (p ...
ry, portable
power tool A power tool is a tool A tool is an object that can extend an individual's ability to modify features of the surrounding environment. Although many animals use simple tools, only human beings, whose use of stone tools dates back hundreds of ...
s or by use of
hand tool A hand tool is any tool A tool is an object that can extend an individual's ability to modify features of the surrounding environment. Although many animals use tool use by animals, simple tools, only human beings, whose use of stone tools ...
s. Wood dust is also the byproduct of certain animals, birds and insects which live in wood, such as the
woodpecker Woodpeckers are part of the Family (biology), family Picidae, which also includes the piculets, wrynecks, and sapsuckers. Members of this family are found worldwide, except for Australia, New Guinea, New Zealand, Madagascar, and the extreme pol ...

woodpecker
and
carpenter ant Carpenter ants (''Camponotus'' spp.) are large () ant Ants are eusocial Eusociality (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, i ...

carpenter ant
. In some
manufacturing Manufacturing is the creation or Production (economics), production of goods with the help of equipment, Work (human activity), labor, machines, tools, and chemical or biological processing or formulation. It is the essence of secondary sector ...
industries it can be a significant
fire hazard #REDIRECT Fire safety#REDIRECT Fire safety Fire safety is the set of practices intended to reduce the destruction caused by fire BBQ. Fire is the rapid oxidation of a material in the exothermic chemical process of combustion, releasing hea ...
and source of occupational dust exposure. Sawdust, as
particulates Particulates – also known as atmospheric aerosol particles, atmospheric particulate matter, particulate matter (PM), or suspended particulate matter (SPM) – are microscopic The microscopic scale (from , ''mikrós'', "small" and σκοπ ...
, is the main component of
particleboard Particle board, also known as chipboard, is an engineered wood product manufactured from wood chips or Jutestick, jute-stick chips and a synthetic resin or other suitable binder, which is pressed and Extrusion, extruded. Particle board is often co ...

particleboard
. Research on health hazards comes from the field of
occupational safety and health Occupational safety and health (OSH), also commonly referred to as occupational health and safety (OHS), occupational health, or occupational safety, is a multidisciplinary field concerned with the safety Safety is the state of being "safe ...
, and study of ventilation happens in
indoor air quality Indoor air quality (IAQ) is the air quality within and around buildings and structures. IAQ is known to affect the health, comfort, and well-being of building occupants. Poor indoor air quality has been linked to Sick Building Syndrome, sick bu ...
engineering.


Formation

Two waste products, dust and chips, form at the working surface during woodworking operations such as sawing, milling and sanding. These operations both shatter lignified wood cells and break out whole cells and groups of cells. Shattering of wood cells creates dust, while breaking out of whole groups of wood cells creates chips. The more cell-shattering that occurs, the finer the dust particles that are produced. For example, sawing and milling are mixed cell shattering and chip forming processes, whereas sanding is almost exclusively cell shattering.


Uses

A major use of sawdust is for particleboard; coarse sawdust may be used for
wood pulp Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fiber Cellulose fibers () are fibers made with ethers or esters of cellulose, which can be obtained from the bark, wood or leaves of plants ...
. Sawdust has a variety of other practical uses, including serving as a
mulch A mulch is a layer of material applied to the surface of soil. Reasons for applying mulch include conservation of soil moisture, improving soil fertility, fertility and health of the soil, reducing Weed control, weed growth and enhancing the vi ...

mulch
, as an alternative to clay
cat litter The cat (''Felis catus'') is a domestic Domestic may refer to: In the home * Anything relating to the human home A home, or domicile, is a space used as a permanent or semi-permanent residence for an individual, group or famil ...

cat litter
, or as a
fuel A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy Thermal radiation in visible light can be seen on this hot metalwork. Thermal energy refers to several distinct physical con ...

fuel
. Until the advent of refrigeration, it was often used in icehouses to keep ice frozen during the summer. It has been used in
artistic displays
artistic displays
, and as scatter in
miniature railroad , 1∶220) placed on the buffer bar of one of the larger (live steam, 1∶8) model locomotives. Railway modelling (UK, Australia, New Zealand, and Ireland) or model railroading (US and Canada) is a hobby in which rail transport systems are mo ...
and other models. It is also sometimes used to soak up liquid spills, allowing the spill to be easily collected or swept aside. As such, it was formerly common on barroom floors. It is used to make
Cutler's resinCutler's Resin, also known as Cutler's Pitch, is a waterproofing adhesive made by including wax when making a Pine Pitch Glue. Cutler's Resin commonly consists of pine A pine is any Pinophyta, conifer in the genus ''Pinus'' () of the family (biol ...
. Mixed with water and frozen, it forms
pykrete Pykrete is a frozen ice alloy, originally made of approximately 14% sawdust or some other form of wood pulp (such as paper) and 86% ice by weight (6 to 1 by weight). During World War II, Geoffrey Pyke proposed it as a candidate material for a Pr ...
, a slow-melting, much stronger form of
ice Ice is water Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in which it acts as a ). It is vital for all known forms of , eve ...

ice
. Sawdust is used in the manufacture of
charcoal briquettes
charcoal briquettes
. The claim for invention of the first commercial charcoal briquettes goes to
Henry Ford Henry Ford (July 30, 1863 – April 7, 1947) was an American industrialist A business magnate is someone who has achieved great success and enormous wealth through the ownership of multiple lines of enterprise. The term characteristicall ...

Henry Ford
who created them from the wood scraps and sawdust produced by his automobile factory.


Food

Cellulose, fibre starch that is indigestible to humans, and a filler in some low calorie foods, can be and is made from sawdust, as well as from other plant sources. While there is no documentation for the persistent rumor, based upon
Upton Sinclair Upton Beall Sinclair Jr. (September 20, 1878 – November 25, 1968) was an American writer, muckraker The muckrakers were reform-minded journalists, writers, and photographers in the Progressive Era The Progressive Era (1896– ...
's novel ''
The Jungle ''The Jungle'' is a 1906 novel by the American journalist and novelist Upton Sinclair Upton Beall Sinclair Jr. (September 20, 1878 – November 25, 1968) was an American writer, muckraker The muckrakers were reform-minded journalis ...
'', that sawdust was used as a filler in sausage, cellulose derived from sawdust was and is used for sausage casings. Sawdust-derived cellulose has also been used as a filler in bread. When cereals were scarce, sawdust was sometimes an ingredient in Kommissbrot.
Auschwitz concentration camp The Auschwitz concentration camp () was a complex of over 40 Nazi concentration camps, concentration and extermination camps operated by Nazi Germany in Polish areas annexed by Nazi Germany, occupied Poland during World War II and the Holocaus ...

Auschwitz concentration camp
survivor, Dr.
Miklós Nyiszli Miklós Nyiszli (17 June 1901 – 5 May 1956) was a Hungarian prisoner of Jewish Jews ( he, יְהוּדִים ISO 259-2 , Israeli pronunciation ) or Jewish people are members of an ethnoreligious group and a nation originating from ...
, reports in ''Auschwitz: A Doctor's Eyewitness Account'' that the subaltern medical staff, who served Dr. Josef Mengele, subsisted on "bread made from wild
chestnuts The chestnuts are a group of eight or nine species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as ...
sprinkled with sawdust."


Health hazards

Airborne sawdust and sawdust accumulations present a number of health and safety hazards. Wood dust becomes a potential health problem when, for example, the wood particles, from processes such as sanding, become airborne and are inhaled. Wood dust is a known human
carcinogen A carcinogen is any substance, radionuclide A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide A nuclide (or nucleide, from atomic nucleus, nucleus, also known as nuclear species) is a class of atoms characte ...
. Certain woods and their dust contain toxins that can produce severe allergic reactions. Breathing airborne wood dust may cause allergic respiratory symptoms, mucosal and non-allergic respiratory symptoms, and cancer. In the US, lists of carcinogenic factors are published by the American Conference of Governmental Industrial Hygienists (ACGIH), the Occupational Safety and Health Administration (OSHA), and the National Institute for Occupational Safety and Health (NIOSH). All these organisations recognize wood dust as carcinogenic in relation to the nasal cavities and paranasal sinuses. People can be exposed to wood dust in the workplace by breathing it in, skin contact, or eye contact. The
Occupational Safety and Health Administration The Occupational Safety and Health Administration (OSHA ) is a large regulatory agency of the United States Department of Labor The United States Department of Labor (DOL) is a cabinet-level department of the U.S. federal government, re ...
(OSHA) has set the legal limit (
permissible exposure limit The permissible exposure limit (PEL or OSHA PEL) is a legal Law is a system A system is a group of Interaction, interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and ...
) for wood dust exposure in the workplace as 15 mg/m3 total exposure and 5 mg/m3 respiratory exposure over an 8-hour workday. The
National Institute for Occupational Safety and Health The National Institute for Occupational Safety and Health (NIOSH, ) is the United States federal agency responsible for conducting research and making recommendations for the prevention of work-related injury Injury, also known as physical ...
(NIOSH) has set a
recommended exposure limit A recommended exposure limit (REL) is an occupational exposure limit An occupational exposure limit is an upper limit on the acceptable concentration of a hazardous substance in workplace air for a particular material or class of materials. It i ...
(REL) of 1 mg/m3 over an 8-hour workday. Water-borne
bacteria Bacteria (; common noun bacteria, singular bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typ ...

bacteria
digest organic material in leachate, but use up much of the available oxygen. This high "biological oxygen demand" can suffocate fish and other organisms. There is an equally detrimental effect on beneficial bacteria, so it is not at all advisable to use sawdust within home aquariums, as was once done by hobbyists seeking to save some expense on
activated charcoal "Activated" is a song by English singer Cher Lloyd Cher Lloyd (born 28 July 1993) is an English singer. She finished fourth place in the The X Factor (UK series 7), seventh series of ''The X Factor (UK TV series), The X Factor'' in 2010. ...

activated charcoal
.


Explosions and fire

Sawdust is flammable and accumulations provide a ready source of fuel. Airborne sawdust can be ignited by sparks or even heat accumulation and result in explosions.


Environmental effects

At
sawmill A sawmill (saw mill, saw-mill) or lumber mill is a facility where logs are cut into lumber Lumber, also known as timber, is wood Wood is a porous and fibrous structural tissue found in the Plant stem, stems and roots of trees and ...

sawmill
s, unless reprocessed into particleboard, burned in a sawdust burner, or used to make heat for other milling operations, sawdust may collect in piles and add harmful
leachate A leachate is any liquid that, in the course of passing through matter, extracts soluble or suspended solids, or any other component of the material through which it has passed. Leachate is a widely used term in the environmental sciences whe ...
s into local water systems, creating an
environmental hazard An environmental hazard is a substance, state or event which has the potential to threaten the surrounding natural environment Environment most often refers to: __NOTOC__ * Natural environment, all living and non-living things occurring naturally ...

environmental hazard
. This has placed small sawyers and environmental agencies in a deadlock. Questions about the science behind the determination of sawdust being an environmental hazard remain for sawmill operators (though this is mainly with finer particles), who compare wood residuals to dead trees in a forest. Technical advisors have reviewed some of the environmental studies, but say most lack standardized methodology or evidence of a direct impact on
wildlife Wildlife traditionally refers to undomesticated animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system that functi ...

wildlife
. They don't take into account large drainage areas, so the amount of material that is getting into the water from the site in relation to the total drainage area is minuscule. Other scientists have a different view, saying the "dilution is the solution to pollution" argument is no longer accepted in environmental science. The decomposition of a tree in a forest is similar to the impact of sawdust, but the difference is of scale. Sawmills may be storing thousands of cubic metres of wood residues in one place, so the issue becomes one of concentration. But of larger concern are substances such as
lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and Bark (botany), bark, because they l ...

lignin
s and
fatty acid In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo during ...
s that protect trees from predators while they are alive, but can leach into water and poison wildlife. Those types of things remain in the tree and, as the tree decays, they slowly are broken down. But when sawyers are processing a large volume of wood and large concentrations of these materials permeate into the runoff, the
toxicity Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacteria, bacterium, or plant, as well as the effect on ...

toxicity
they cause is harmful to a broad range of organisms.


Wood flour

Wood flour is finely pulverized
wood Wood is a porous and fibrous structural tissue found in the stems and roots of tree In botany, a tree is a perennial plant with an elongated Plant stem, stem, or trunk (botany), trunk, supporting branches and leaves in most species. ...

wood
that has a consistency fairly equal to sand or sawdust, but can vary considerably, with particles ranging in dimensions from a fine powder to roughly that of a grain of rice. Most wood flour manufacturers are able to create batches of wood flour that have the same consistency throughout. All high quality wood flour is made from
hardwood Hardwood is wood Wood is a porous and fibrous structural tissue found in the stems and roots of tree In botany, a tree is a perennial plant with an elongated Plant stem, stem, or trunk (botany), trunk, supporting branches and ...

hardwood
s because of its durability and strength. Very low grade wood flour is occasionally made from sapless
softwood Scots Pine, a typical and well-known softwood Softwood is wood Wood is a porous and fibrous structural tissue found in the stems and roots of tree In botany, a tree is a perennial plant with an elongated Plant stem, stem, or t ...
s such as
pine A pine is any conifer Conifers are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The div ...

pine
or
fir Firs (''Abies'') are a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology Biology is the natural science that studies life and living organisms, including ...

fir
.


Applications

Wood flour is commonly used as a filler in thermosetting resins such as
bakelite Bakelite ( ; sometimes spelled Baekelite) or polyoxybenzylmethylenglycolanhydride was the first plastic made from synthetic components. It is a thermosetting polymer, thermosetting phenol formaldehyde resin, formed from a condensation reaction o ...

bakelite
, and in
linoleum Linoleum, commonly shortened to lino, is a floor covering made from materials such as solidified linseed oil (linoxyn), pine resin, ground cork dust, sawdust Sawdust (or wood shavings) is a by-product or waste product of woodworking oper ...

linoleum
floor coverings. Wood flour is also the main ingredient in wood/plastic composite building products such as decks and roofs. Prior to 1920, wood flour was used as the filler in ¼-inch thick Edison Diamond Discs. Wood flour has found a use in plugging small through-wall holes in leaking main condenser (
heat exchanger A heat exchanger is a system used to transfer heat between two or more fluid In physics, a fluid is a substance that continually Deformation (mechanics), deforms (flows) under an applied shear stress, or external force. Fluids are a Phase (m ...

heat exchanger
) tubes at electrical power generating stations via injecting small quantities of the wood flour into the cooling water supply lines. Some of the injected wood flour clogs the small holes while the remainder exits the station in a relatively environmentally benign fashion. Wood flour can be used as a binder in
grain fillerA grain filler (pore filler or paste wood filler) is a woodworking product that is used to achieve a smooth-textured wood finishing, wood finish by filling pores in the wood grain. It is used particularly on open grained woods such as oak, mahogany a ...
compounds.


Sources

Large quantities of wood flour are frequently to be found in the waste from woodworking and furniture companies. An
adaptive reuse Adaptive reuse refers to the process of reusing Reuse is the action or practice of using an item, whether for its original purpose (conventional reuse) or to fulfil a different function (creative reuse or repurposing). It should be distinguished f ...
to which this material can be directed is
compost Compost is a mixture of ingredients used to fertilize and improve the soil. It is commonly prepared by decomposing plant and food waste and recycling Recycling is the process of converting waste Waste (or wastes) are unwanted ...

compost
ing. Wood flour can be subject to
dust explosion A dust explosion is the rapid combustion Combustion, or burning, is a high-temperature exothermic In thermodynamics Thermodynamics is a branch of physics that deals with heat, Work (thermodynamics), work, and temperature, and their relat ...
s if not cared for and disposed of properly.


Respirable particulates

As with all airborne
particulates Particulates – also known as atmospheric aerosol particles, atmospheric particulate matter, particulate matter (PM), or suspended particulate matter (SPM) – are microscopic The microscopic scale (from , ''mikrós'', "small" and σκοπ ...
, wood dust particle sizes are classified with regard to effect on the human respiratory system. For this classification, the unit for measurement of particle sizes is the micrometre or micron (μm), where 1 micrometre = 1 micron. Particles below 50 μm are not normally visible to the naked human eye. Particles of concern for human respiratory health are those <100 μm (where the symbol < means ‘less than’). Zhang (2004) has defined the size of indoor particulates according to respiratory fraction: Particles which precipitate in the vicinity of the mouth and eyes, and get into the organism, are defined as the inhalable fraction, that is total dust. Smaller fractions, penetrating into the non-cartilage respiratory tract, are defined as respirable dust. Dust emitted in the wood industry is characterized by the dimensional disintegration of particles up to 5 μm, and that is why they precipitate mostly in the nasal cavity, increasing the risk of cancer of the upper respiratory tract.


Exposure

The parameter most commonly used to characterize exposures to wood dust in air is total wood dust concentration, in mass per unit volume. In countries that use the metric system, this is usually measured in mg/m3 (milligram per cubic metre) A study to estimate occupational exposure to inhalable wood dust by country, industry, the level of exposure and type of wood dust in 25 member states of the European Union (EU-25) found that in 2000–2003, about 3.6 million workers (2.0% of the employed EU-25 population) were occupationally exposed to inhalable wood dust. The highest exposure levels were estimated to occur in the construction sector and furniture industry.


Cancer

Wood dust is known to be a human carcinogen, based on sufficient evidence of carcinogenicity from studies in humans. It has been demonstrated through human epidemiologic studies that exposure to wood dust increases the occurrence of cancer of the nose (nasal cavities and paranasal sinuses). An association of wood dust exposure and cancers of the nose has been observed in numerous case reports, cohort studies, and case control studies specifically addressing nasal cancer.


Ventilation

To lower the concentration of airborne dust concentrations during woodworking, dust extraction systems are used. These can be divided into two types. The first are local exhaust ventilation systems, the second are room ventilation systems. Use of personal
respirator A respirator is a device designed to protect the wearer from inhaling hazardous atmospheres, including fumes, vapours, gases Gas is one of the four fundamental states of matter (the others being solid Solid is one of the four ...
s, a form of
personal protective equipment Personal protective equipment (PPE) is protective clothing A kanga, worn throughout the African Great Lakes region Clothing (also known as clothes, apparel, and attire) are items worn on the body. Typically, clothing is made of fabr ...
, can also isolate workers from dust.


Local exhaust

Local exhaust ventilation (LEV) systems rely on air pulled with a suction force through piping systems from the point of dust formation to a waste disposal unit. They consist of four elements: dust hoods at the point of dust formation, ventilation ducts, an air cleaning device (waste separator or dust collector) and an air moving device (a fan, otherwise known as an impeller). The air, containing dust and chips from the woodworking operation, is sucked by an impeller. The impeller is usually built into, or placed close to, the waste disposal unit, or dust collector. Guidelines of performance for woodworking LEV systems exist, and these tie into occupational air quality regulations that exist in many countries. The LEV guidelines often referred to are those set by the ACIAH.


Low volume/high velocity

Low-volume/high-velocity (LVHV) capture systems are specialised types of LEV that use an extractor hood designed as an integral part of the tool or positioned very close to the operating point of the cutting tool. The hood is designed to provide high capture velocities, often greater than 50 m/s (10,000 fpm) at the contaminant release point. This high velocity is accompanied by airflows often less than 0.02m3/s (50 cfm) resulting from the small face area of the hood that is used. These systems have come into favour for portable power tools, although adoption of the technology is not widespread. Festool is one manufacturer of portable power tools using LVHV ventilation integrated into the tool design.


Room

If suitably designed, general ventilation can also be used as a control of airborne dust. General ventilation can often help reduce skin and clothing contamination, and dust deposition on surfaces.WHO, 1999. Hazard Prevention and Control in the Work Environment: Airborne Dust. WHO/SDE/OEH/99.14. Geneva: World Health Organization, Department of Protection of the Human Environment, Occupational and Environmental Health. p. 98.
/ref>


See also

*
Dust collection system A dust collection system is an air quality Air pollution is the presence of substances in the atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ''(sphaira)'', meaning 'ball' or 'sph ...
*
Dust collector A dust collector is a system used to enhance the quality of air released from industrial and commercial processes by collecting dust and other impurities from air or gas. Designed to handle high-volume dust loads, a dust collector system consists ...
*
Particulates Particulates – also known as atmospheric aerosol particles, atmospheric particulate matter, particulate matter (PM), or suspended particulate matter (SPM) – are microscopic The microscopic scale (from , ''mikrós'', "small" and σκοπ ...
*
Swarf upright=1.35, Various examples of swarf, including a block of compressed swarf Swarf, also known as chips or by other process-specific names (such as turnings, filings, or shavings), are pieces of metal, wood, or plastic that are the debris or w ...


References


WHO 2005. ''Air Quality Guidelines for Europe'', 2nd ed. WHO regional publications. European series, No. 91. Copenhagen: WHO Regional Office for Europe.


External links


BillPentz.com: Dust Collection Research.
{{Authority control Environmental chemistry Saws Waste Woodworking IARC Group 1 carcinogens Wood fuel Wood products Dust