Dust is made of
fine particles of solid
matter
In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic part ...
. On Earth, it generally consists of particles in the
atmosphere that come from various sources such as
soil
Soil, also commonly referred to as earth or dirt
Dirt is an unclean matter, especially when in contact with a person's clothes, skin, or possessions. In such cases, they are said to become dirty.
Common types of dirt include:
* Debri ...
lifted by wind (an
aeolian process
Aeolian processes, also spelled eolian, pertain to wind activity in the study of geology and weather and specifically to the wind's ability to shape the surface of the Earth (or other planets). Winds may erode, transport, and deposit materials ...
),
volcanic eruptions
Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often ...
, and
pollution. Dust in homes is composed of about 20–50% dead
skin cells. The rest, and in offices, and other
human environments is composed of small amounts of plant
pollen, human
hairs, animal
fur
Fur is a thick growth of hair that covers the skin of mammals. It consists of a combination of oily guard hair on top and thick underfur beneath. The guard hair keeps moisture from reaching the skin; the underfur acts as an insulating blanket t ...
,
textile fibers,
paper
Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distrib ...
fibers,
mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...
s from outdoor soil, burnt
meteorite particles, and many other
materials which may be found in the local environment.
Atmospheric
Atmospheric or wind-borne
fugitive dust
Fugitive dust is an environmental air quality term for very small particles suspended in the air, primarily mineral dust that is sourced from the soil of Earth's pedosphere. A significant volume of fugitive dust that is visible from a distance ...
, also known as ''aeolian dust'', comes from arid and dry regions where high velocity winds are able to remove mostly silt-sized material, deflating susceptible surfaces. This includes areas where
grazing,
ploughing,
vehicle
A vehicle (from la, vehiculum) is a machine that transports people or cargo. Vehicles include wagons, bicycles, motor vehicles (motorcycles, cars, trucks, buses, mobility scooters for disabled people), railed vehicles (trains, trams), ...
use, and other
human behavior
Human behavior is the potential and expressed capacity ( mentally, physically, and socially) of human individuals or groups to respond to internal and external stimuli throughout their life. Kagan, Jerome, Marc H. Bornstein, and Richard M. ...
s have further destabilized the
land
Land, also known as dry land, ground, or earth, is the solid terrestrial surface of the planet Earth that is not submerged by the ocean or other bodies of water. It makes up 29% of Earth's surface and includes the continents and various isla ...
, though not all source areas have been largely affected by
anthropogenic impacts.
One-third of the global land area is covered by dust-producing surfaces, made up of
hyper-arid regions like the
Sahara which covers 0.9 billion hectares, and
drylands which occupy 5.2 billion hectares.
Dust in the atmosphere is produced by
saltation and
abrasive sandblasting of sand-sized grains, and it is transported through the
troposphere
The troposphere is the first and lowest layer of the atmosphere of the Earth, and contains 75% of the total mass of the planetary atmosphere, 99% of the total mass of water vapour and aerosols, and is where most weather phenomena occur. From ...
. This airborne dust is considered an
aerosol and once in the atmosphere, it can produce strong local
radiative forcing. Saharan dust, in particular, can be transported and deposited as far as the
Caribbean and the
Amazon basin, and may affect air
temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measurement, measured with a thermometer.
Thermometers are calibrated in various Conversion of units of temperature, temp ...
s, cause ocean cooling, and alter rainfall amounts.
Middle East
Dust in the Middle East has been a historic phenomenon. Recently, because of
climate change
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
and the escalating process of
desertification, the problem has worsened dramatically. As a multi-factor phenomenon, there is not yet a clear consensus on the sources or potential solutions to the problem.
In Iran, the dust is already affecting more than 5 million people directly, and has emerged as a serious government issue in recent years. In the
Khuzestan Province
Khuzestan Province (also spelled Xuzestan; fa, استان خوزستان ''Ostān-e Xūzestān'') is one of the 31 provinces of Iran. It is in the southwest of the country, bordering Iraq and the Persian Gulf. Its capital is Ahvaz and it covers ...
, it has led to the severe increase of
air pollution
Air pollution is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. There are many different typ ...
. The amount of
pollutant
A pollutant or novel entity is a substance or energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource. These can be both naturally forming (i.e. minerals or extracted compounds like o ...
s in the air has surpassed more than 50 times the normal level several times in a year. Recently, initiatives such as Project-Dust have been established to directly study dust in the Middle East.
Roads
Dust kicked up by vehicles traveling on
roads may make up 33% of air pollution. Road dust consists of deposits of vehicle and industrial
exhaust gas
Exhaust gas or flue gas is emitted as a result of the combustion of fuels such as natural gas, gasoline (petrol), diesel fuel, fuel oil, biodiesel blends, or coal. According to the type of engine, it is discharged into the atmosphere through an ...
, particles from
tire and
brake wear, dust from paved roads or
potholes, and dust from
construction
Construction is a general term meaning the art and science to form Physical object, objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Pr ...
sites. Road dust is a significant contributor to the generation and release of
particulates into the atmosphere. Control of road dust is a significant challenge in
urban areas, and also in other locations with high levels of vehicular traffic upon unsealed roads, such as mines and
landfills.
Road dust may be suppressed by mechanical methods like
street sweeper
A street sweeper or street cleaner may refer to a person's occupation or to a machine that cleans streets.
Street sweepers have been employed in cities as "sanitation workers" since sanitation and waste removal became a priority. A stre ...
, vehicles equipped with
vacuum cleaners,
vegetable oil
Vegetable oils, or vegetable fats, are oils extracted from seeds or from other parts of fruits. Like animal fats, vegetable fats are ''mixtures'' of triglycerides. Soybean oil, grape seed oil, and cocoa butter are examples of seed oils, or f ...
sprays,
or with water sprayers.
Calcium chloride
Calcium chloride is an inorganic compound, a salt with the chemical formula . It is a white crystalline solid at room temperature, and it is highly soluble in water. It can be created by neutralising hydrochloric acid with calcium hydroxide.
Ca ...
can be used. Improvements in
automotive engineering have reduced the amount of
PM10s produced by road traffic; the proportion representing re-suspension of existing particulates has increased as a result.
Coal
Coal dust Coal dust is a fine powdered form of which is created by the crushing, grinding, or pulverizing of coal. Because of the brittle nature of coal, coal dust can be created during mining, transportation, or by mechanically handling coal. It is a form ...
is responsible for the
respiratory disease
Respiratory diseases, or lung diseases, are pathological conditions affecting the organs and tissues that make gas exchange difficult in air-breathing animals. They include conditions of the respiratory tract including the trachea, bronchi, bro ...
known as
pneumoconiosis, including
Coalworker's pneumoconiosis disease that occurs among
coal miners
People have worked as coal miners for centuries, but they became increasingly important during the Industrial revolution when coal was burnt on a large scale to fuel stationary and locomotive engines and heat buildings. Owing to coal's strategic ro ...
. The danger of coal dust resulted in
environmental law regulating workplace air quality in some jurisdictions. In addition, if enough coal dust is dispersed within the air in a given area, in very rare circumstances, it can cause a
dust explosion
A dust explosion is the rapid combustion of fine particles suspended in the air within an enclosed location. Dust explosions can occur where any dispersed powdered combustible material is present in high-enough concentrations in the atmosphere o ...
. These circumstances are typically within confined spaces.
Control
Atmospheric
Most governmental Environmental Protection Agencies, including the
United States Environmental Protection Agency
The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it ...
(EPA) mandate that facilities that generate fugitive dust, minimize or mitigate the production of dust in their operation. The most frequent dust control violations occur at new residential housing developments in urban areas. United States federal law requires that construction sites obtain
planning permissions to conduct earth moving and clearing of areas, so that plans to control dust emissions while the work is being carried out are specified. Control measures include such simple practices as spraying construction and
demolition sites with water, and preventing the tracking of dust onto adjacent roads.
Some of the issues include:
*Reducing dust related health risks that include
allergic reactions,
pneumonia
Pneumonia is an inflammatory condition of the lung primarily affecting the small air sacs known as alveoli. Symptoms typically include some combination of productive or dry cough, chest pain, fever, and difficulty breathing. The severi ...
and
asthma
Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, co ...
tic attacks.
*Improving
visibility and
road traffic safety.
*Providing cleaner air, cleaner vehicles and cleaner homes and promoting better health.
*Improving
agricultural productivity
Agricultural productivity is measured as the ratio of agricultural outputs to inputs. While individual products are usually measured by weight, which is known as crop yield, varying products make measuring overall agricultural output difficu ...
.
*Reducing vehicle maintenance costs by lowering the levels of dust that clog filters, bearings and machinery.
*Reducing driver fatigue, maintenance on
car suspension
Suspension is the system of tires, tire air, springs, shock absorbers and linkages that connects a vehicle to its wheels and allows relative motion between the two. Suspension systems must support both road holding/ handling and ride ...
systems and improving
fuel economy in automobiles.
*Increasing
cumulative effects—each new application builds on previous progress.
US federal laws require dust control on sources such as vacant lots, unpaved
parking lots, and
dirt roads. Dust in such places may be suppressed by mechanical methods, including paving or laying down
gravel, or stabilizing the surface with water, vegetable oils
or other
dust suppressants, or by using water misters to suppress dust that is already airborne.
Domestic
Dust control is the suppression of solid particles with diameters less than 500micrometers (''i.e.'' half a millimeter). Dust poses a health risk to children, older people, and those with respiratory diseases.
House dust can become airborne easily. Care is required when removing dust to avoid causing the dust to become airborne. A
feather duster
A feather duster is a cleaning tool that is typically made from a wooden dowel handle onto which ostrich feathers are wound with a wire. The feathers are most often long. Some dusters have a retractable casing instead of a dowel handle and thes ...
tends to agitate the dust so it lands elsewhere.
Certified
HEPA (tested to MIL STD 282) can effectively trap 99.97% of dust at 0.3 micrometers. Not all HEPA filters can effectively stop dust; while vacuum cleaners with HEPA filters, water, or cyclones may filter more effectively than without, they may still exhaust millions of particles per cubic foot of air circulated.
Central vacuum cleaners can be effective in removing dust, especially if they are exhausted directly to the outdoors.
Air filter
A particulate air filter is a device composed of fibrous, or porous materials which removes solid particulates such as dust, pollen, mold, and bacteria from the air. Filters containing an adsorbent or catalyst such as charcoal (carbon) may a ...
s differ greatly in their
effectiveness. Laser particle counters are an effective way to measure filter effectiveness, medical grade instruments can test for particles as small as 0.3 micrometers. In order to test for dust in the air, there are several options available. Pre-weighed filter and matched weight filters made from
polyvinyl chloride or mixed
cellulose ester are suitable for respirable dust (less than 10 micrometers in diameter).
Dust resistant surfaces
A dust resistant surface is a state of prevention against dust contamination or damage, by a design or treatment of materials and items in
manufacturing or through a repair process . A reduced
tacticity
Tacticity (from el, τακτικός, taktikos, "relating to arrangement or order") is the relative stereochemistry of adjacent chiral centers within a macromolecule. The practical significance of tacticity rests on the effects on the physical ...
of a synthetic layer or covering can protect surfaces and release small molecules that could have remained attached. A panel, container or enclosure with
seams may feature types of strengthened
structural rigidity
In discrete geometry and mechanics, structural rigidity is a combinatorial theory for predicting the flexibility of ensembles formed by rigid bodies connected by flexible linkages or hinges.
Definitions
Rigidity is the property of a struct ...
or
sealant
Sealant is a substance used to block the passage of fluids through openings in materials, a type of mechanical seal. In building construction ''sealant'' is sometimes synonymous with '' caulking'' and also serve the purposes of blocking dust, so ...
to vulnerable
edges and
joins Join may refer to:
* Join (law), to include additional counts or additional defendants on an indictment
*In mathematics:
** Join (mathematics), a least upper bound of sets orders in lattice theory
** Join (topology), an operation combining two topo ...
.
Outer space
Cosmic dust is widely present in
outer space
Outer space, commonly shortened to space, is the expanse that exists beyond Earth and its atmosphere and between celestial bodies. Outer space is not completely empty—it is a near-perfect vacuum containing a low density of particles, pred ...
, where gas and dust clouds are the primary precursors for
planetary systems. The
zodiacal light, as seen in a dark night sky, is produced by
sunlight reflected from particles of dust in orbit around the
Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
. The tails of
comet
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ...
s are produced by emissions of dust and ionized gas from the body of the comet. Dust also covers solid planetary bodies, and vast
dust storms can occur on
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...
which cover almost the entire planet. Interstellar dust is found between the
stars, and high concentrations produce
diffuse nebulae
A nebula ('cloud' or 'fog' in Latin; pl. nebulae, nebulæ or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral or molecular hydrogen and also cosmic dust. Nebulae are often star-forming region ...
and
reflection nebulae.
Dust is widely present in the
galaxy. Ambient
radiation heats dust and re-emits radiation into the
microwave band, which may distort the
cosmic microwave background power spectrum. Dust in this regime has a complicated
emission spectrum and includes both thermal dust emission and
spinning dust emission.
Dust samples returned from outer space have provided information about conditions of the early
solar system
The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...
. Several
spacecraft have sought to gather samples of dust and other materials. Among these craft was
Stardust, which flew past
81P/Wild
Comet 81P/Wild, also known as Wild 2 (pronounced "vilt two") ( ), is a comet named after Swiss astronomer Paul Wild, who discovered it on January 6, 1978, using a 40-cm Schmidt telescope at Zimmerwald, Switzerland.
For most of its 4.5 billion ...
in 2004, and returned a capsule of the comet's remains to Earth. In 2010 the Japanese
Hayabusa
was a robotic spacecraft developed by the Japan Aerospace Exploration Agency (JAXA) to return a sample of material from a small near-Earth asteroid named 25143 Itokawa to Earth for further analysis.
''Hayabusa'', formerly known as MUSES-C fo ...
spacecraft returned samples of dust from the surface of an
asteroid.
Atmospheric gallery
Image:Dust over Southeast Australia.jpg, Dry, windy weather sends clouds of dust across south-eastern Australia.
Image:Spring Bloom and Dust off Argentina.jpg, A pale brown plume of dust sweeps out of Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
’s Pampas.
Image:Dust Extends from Saudi Arabia to Iran.jpg, A thick dust plume over Kuwait
Kuwait (; ar, الكويت ', or ), officially the State of Kuwait ( ar, دولة الكويت '), is a country in Western Asia. It is situated in the northern edge of Eastern Arabia at the tip of the Persian Gulf, bordering Iraq to the nort ...
and the north-western tip of the Persian Gulf
Dust mites
House dust mite
House dust mites (HDM, or simply dust mites) are various species of acariform mites belonging to the family Pyroglyphidae that are found in association with dust in dwellings. They are known for causing allergies.
Biology
Species
The curren ...
s are present indoors wherever humans live.
Positive tests for dust mite allergies are extremely common among people with asthma. Dust mites are microscopic
arachnid
Arachnida () is a class of joint-legged invertebrate animals (arthropods), in the subphylum Chelicerata. Arachnida includes, among others, spiders, scorpions, ticks, mites, pseudoscorpions, harvestmen, camel spiders, whip spiders and vinegar ...
s whose primary food is dead human skin cells, but they do not live on living people. They and their feces and other
allergens that they produce are major constituents of house dust, but because they are so heavy they are not suspended for long in the air. They are generally found on the floor and other surfaces, until disturbed (by walking, for example).
It could take somewhere between twenty minutes and two hours for dust mites to settle back down out of the air.
Dust mites are a nesting species that prefer a dark, warm, and humid
climate
Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologi ...
. They flourish in
mattresses,
bedding
Bedding, also known as bedclothes or bed linen, is the materials laid above the mattress of a bed for hygiene, warmth, protection of the mattress, and decorative effect. Bedding is the removable and washable portion of a human sleeping environm ...
,
upholstered furniture, and
carpets. Their feces include
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...
s that are released upon contact with a moist surface, which can happen when a person inhales, and these enzymes can kill cells within the
human body. House dust mites did not become a problem until humans began to use textiles, such as western style
blanket
A blanket is a swath of soft cloth large enough either to cover or to enfold most of the user's body and thick enough to keep the body warm by trapping radiant body heat that otherwise would be lost through convection.
Etymology
The term ...
s and
clothing.
See also
*
Contamination control
*
Dust bunny
*
Dust explosion
A dust explosion is the rapid combustion of fine particles suspended in the air within an enclosed location. Dust explosions can occur where any dispersed powdered combustible material is present in high-enough concentrations in the atmosphere o ...
*
Hanānā
*
Lint (material)
Lint is the common name for visible accumulations of textile fibers and other materials, usually found on and around clothing. Certain materials used in the manufacture of clothing, such as cotton, linen, and wool, contain numerous, very shor ...
*
Medical geology
*
Mineral dust
*
Nephelometer
A nephelometer or aerosol photometer is an instrument for measuring the concentration of suspended particulates in a liquid or gas colloid. A nephelometer measures suspended particulates by employing a light beam (source beam) and a light dete ...
*
Occupational dust exposure
*
Sawdust
Sawdust (or wood dust) is a by-product or waste product of woodworking operations such as sawing, sanding, milling, planing, and routing. It is composed of small chippings of wood. These operations can be performed by woodworking machine ...
References
Further reading
* Holmes, Hannah; (2001)''The Secret Life of Dust''. Wiley.
* Steedman, Carolyn; (2002) ''Dust''.
Manchester University Press.
External links
Global map of atmospheric dust
{{Authority control
Articles containing video clips