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{{wiktionarypar|dust}}
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[[Image:Laptop dust.jpg|200px|thumb|Three years of solid usage has blocked this [[laptop]] [[heat sink]] with '''dust''', making the computer unusable]]
'''Dust''' is a general name for minute [[solid]] particles with [[diameter]]s less than 500 [[micrometre|micrometers]]. On [[Earth]], dust occurs in the [[Earth's atmosphere|atmosphere]] from various sources; [[soil]] dust lifted up by [[wind]], [[volcanic eruptions]], and [[pollution]] are some examples. Airborne dust is considered an [[Particulate|aerosol]] and can have a strong local [[radiative forcing]] on the atmosphere and significant effects on [[climate]]. In addition, if enough of the minute particles are dispersed within the air in a given area (such as flour or coal dust), under certain circumstances this can be an [[Dust explosion|explosion]] hazard. 

[[Coal dust]] is responsible for the [[lung]] disease known as [[Pneumoconiosis]], including [[black lung]] disease, which occurs among [[coal]] miners. This danger has resulted in a number of laws regulating environmental standards for working conditions.

==Dust in outer space==
[[Cosmic dust]] is widely present in space, where [[gas]] and dust clouds are primary precursors for [[planetary systems]]. The [[zodiacal light]], seen in the sky on a dark night, is produced by sunlight reflected from particles of dust in orbit around the [[Sun]]. The tails of [[comet]]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 storm]]s can occur on [[Mars (planet)|Mars]] that can cover almost the entire planet. [[Interstellar dust]] is found between the stars, and high concentrations can produce [[diffuse nebulae]] and [[reflection nebulae]].

Dust samples returned from outer space could provide information about conditions in the early [[solar system]]. Several [[spacecraft]] have been launched in an attempt to gather samples of dust and other materials. Among these was [[Stardust (spacecraft)|Stardust]], which flew past [[Comet Wild 2]] in 2004  and returned a capsule of the comet's remains to Earth in January 2006. The [[Japan]]ese [[Hayabusa]] spacecraft is currently on a mission to collect samples of dust from the surface of an [[asteroid]].
==Domestic dust==

Dust in homes, offices, and other human environments consists of human [[skin|skin cells]], plant [[pollen]], human and animal [[hairs]], [[textiles|textile fibers]], [[paper|paper fibers]], [[minerals]] from outdoor [[soil]] and dust, and many other materials which may be found in the local environment.<ref name="hesskosa">Kathleen Hess-Kosa, (2002), ''Indoor Air Quality: sampling methodologies'', page 216. CRC Press.</ref> The precise composition of domestic dust can vary widely:
<blockquote>The quantity and composition of house dust varies greatly with [[seasonal]] and [[Natural environment|environmental]] factors such as the surroundings, exchange of outside [[air]], age of the [[house]], building materials and their condition, and the quantity of [[furniture]] and [[carpets]], as well as their state of preservation. It varies further with [[ventilation]] and [[Central heating|heating systems]], [[cleaning|cleaning habits]], activities of the occupants or users of a room, etc. House dust consists of [[inorganic]] and [[Organic compound|organic]] matter, yet the relative proportions of these components may vary considerably. "House dust" from [[kindergartens]] often consists almost completely of inorganic materials such as [[sand]], [[loam]], and [[clay]] from [[sand pit|sand pits]]. On the other hand, house dust from residences of animal owners with worn out carpets may consist nearly completely of organic material. The proportion of organic matter in 318 house dust samples was found to vary between <5% and >95% (Butte and Walker, 1994). Fergusson et al. (1986) reported the organic content of house dust from 11 homes in [[Christchurch, New Zealand]], to be within the range from 25.7% to 41.5%. Floor dust from seven [[Denmark|Danish]] offices had a [[arithmetic mean|mean]] organic fraction of 33% (Mølhave et al., 2000).<ref>Lidia Morawska, Tunga Salthammer, (2003), ''Indoor Environment: Airborne Particles and Settled Dust'', page 409. Wiley-VCH.</ref></blockquote>

According to the ''German Environmental Survey'', approximately 6 mg/m²/day of house dust is formed in private households,<ref>George W. Ware, (2002), ''Reviews of Environmental Contamination and Toxicology'', page 4. Springer.</ref> depending primarily on the amount of time spent at home. Nearly 1000 dust particles per [[square centimeter]] settle on domestic surfaces every hour.<ref name="hesskosa"/> Some dust consists of human [[skin]]; it is estimated that the entire outer layer of skin is shed every day or two at a rate of 7 million skin flakes per minute, which corresponds to a mass emission rate of about 20 mg/minute.<ref>Heinsohn, R., Cimbala, J., (2003) ''Indoor Air Quality Engineering: Environmental Health and Control of Indoor Pollutants.'' page 146. CRC Press.</ref>

Insects and other small fauna found in houses have their own subtle interactions with dust that may have adverse impact on the health of its [[human|regular occupants]]. Thus, in many climates it is wise to keep a modicum of airflow going through a house, by keeping doors and windows open or at least slightly ajar. In colder climates, it is essential to manage dust and airflow, since the climate encourages occupants to seal even the smallest air gaps, and thus eliminate any possibility of fresh air entering.

[[House dust mite]]s are on all surfaces and even suspended in air. Dust mites feed on minute particles of organic matter, the main constituent of house dust. They excrete enzymes to digest dust particles; these enzymes and their feces, in turn, become part of house dust and can provoke allergic reactions in humans. Dust mites flourish in the fibers of bedding, furniture, and carpets. 

The particles that make up house dust can easily become airborne, so care must be exercised when removing dust, as the activity intended to sanitize or remove dust may make it airborne. One way to repel dust is with some kind of electrical charge, but house dust can be removed by many methods, including wiping, swiping, or sweeping by hand, or with a dust cloth, sponge, [[feather duster]], or broom, or by suction by a [[vacuum cleaner]] or [[air filter]]. The device being used traps the dust; however, some may become airborne and come to settle in the cleaner's lungs, thus making the activity somewhat hazardous. "[[Dust bunny|Dust bunnies]]" are little clumps of fluff that form when sufficient dust accumulates. Dust is known to worsen [[hay fever]].

==Dust control==
Dust control  is the suppression of solid particles with diameters less than 500 micrometers.  Because dust in the air is a serious health threat to children, older people, and those with respiratory illnesses, the U. S. Environment Protection Agency (EPA) mandates facilities that generate dust must work to minimize it in their operations.  

The most frequent dust control violations occurred at new residential housing developments in urban areas.  Federal law requires permits for earth moving at construction sites, include plans to control dust emissions. Control measures include such simple practices as watering down construction and demolition sites, as well as preventing dust from being tracked out onto adjacent roads.  In addition, federal laws require dust controls on sources such as vacant lots, unpaved parking lots, and unpaved roads.  Control measures for these sources include paving, gravel, or stabilizing the surface with water or other dust suppressants.

==Dust in fiction==
{{trivia|date=April 2008}}

*In [[James Matthew Barrie|JM Barrie]]'s children's novel ''[[Peter Pan]]'' (1911), "[[pixie dust]]" is a substance used to help make people fly who can't already.
*In [[Clark Ashton Smith]]'s short [[Horror fiction|horror]] story "The Treader In The Dust" (1935) [http://www.eldritchdark.com/writings/short-stories/222/the-treader-of-the-dust], a scholar unwittingly calls forth a demon that personifies dustiness.
*In [[Arthur C. Clarke]]'s ''[[A Fall of Moondust]]'' (1961), 21st century tourists "cruise" across the Moon's "Seas" that have filled over eons with very fine dust, which is so fine that it almost behaves like water.
*In [[Hal Clement]]'s short [[science fiction]] story "Dust Rag" (1965), two astronauts struggle with dust that stuck to their helmets, blinding them.
*In the science fiction series [[Babylon 5]], Dust was a psychoactive illegal drug that enhanced latent telepathic abilities in non-humanoids, that often led to fatalities in both the user and "victim".
*In the novel by [[Phillip Pullman]], [[His Dark Materials]] trilogy referrs to a shadow particle that created angels and is a concious particle.  It created the first angel, the Authority, not God, and in the trilogy a young girl named Lyra and a boy name Will try to find out what Dust is in order to save it and destroy the Authority thus building a Republic of Heaven that lets the dead rise again. (1995-2000)
*In the T.V. series [[Buffy the Vampire Slayer]] by [[Joss Whedon]], vampires are reduced to dust when staked- or "dusted"- a reference to earlier mythology in which vampires consist of earth or dust.

==Dust in religion==
In ancient Sumerian mythology:
*The afterlife consists of the dreary "House of Dust and Darkness".
In the [[Bible]]:
*In [[Genesis]] 3:19, God — following [[Fall of Man|The Fall]], Adam and Eve's transgression — states to the couple: 
:By the sweat of your brow you will eat your food until you return to the ground, since from it you were taken; ''for dust you are and to dust you will return.'' [Emphasis added]
This latter clause is used in the [[Ash Wednesday]] service in some churches for the administering of ashes, and is adapted in funeral services to the common prayer "[[Dust to Dust]]".
*In [[Genesis]] 13:16, God states to [[Abram]] (later Abraham):
:I will make your offspring like the dust of the earth, so that if anyone could count the dust, then your offspring could be counted.

Note however that in both of these Biblical passages, the Hebrew word is [[wikt:עפר|עפר]] (`âfâr), which can also mean earth or [[soil|dirt]].

*Micah 7:17, "They shall lick dust like a serpent..."

*John 8:1-11 features Jesus "writing on the ground."  Many translators substitute "dust" for "ground". This scripture provides the only witness of any writing by Jesus. The choice of dust as a medium for writing has created speculation as to what Jesus wrote.

==See also==

*[[Contamination control]]
*[[Dust explosion]]
*[[Medical geology]]

==References==
*Holmes, Hannah; (2001)''The Secret Life of Dust''. Wiley. ISBN 0-471-37743-0
*Steedman, Carolyn; (2002) ''Dust''. Manchester University Press. ISBN-13: 978-0719060151
{{reflist}}

==External links==
*[http://www.lbk.ars.usda.gov/wewc/biblio/bar.htm The Bibliography of Aeolian Research]
*[http://www.daab.de/ The German Asthma & Allergy Federation (DAAB)]  {{de icon}}

[[Category:Granular materials]]
[[Category:Waste]]

[[ca:Pols (partícules)]]
[[cs:Prach]]
[[de:Staub]]
[[es:Polvo]]
[[fr:Poussière]]
[[id:Debu]]
[[ia:Pulvere]]
[[is:Ryk]]
[[it:Polvere]]
[[he:אבק]]
[[la:Pulvis]]
[[nl:Stof (kleine deeltjes)]]
[[ja:粉塵]]
[[no:Støv]]
[[pl:Kurz]]
[[pt:Poeira]]
[[ru:Пыль]]
[[scn:Pruvulazzu]]
[[sk:Prach]]
[[sr:Прашина]]
[[fi:Pöly]]
[[sv:Damm (stoft)]]
[[vi:Bụi]]
[[uk:Пил]]
[[zh:灰塵]]

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