Dust

From Wikipedia, the free encyclopedia

For other uses, see Dust (disambiguation).

After just three years of use dust has blocked this laptop heat sink, making the computer unusable

Dust is a general name for minute solid particles with diameters less than 500 micrometers (otherwise, see sand or granulates) and, more generally, for finely divided matter. On Earth dust occurs in the atmosphere from various sources: soil dust lifted up by wind, volcanic eruptions, and pollution are some examples. Airborne dust is considered an aerosol and can have a strong local radiative forcing on the atmosphere and significant effects on climate. In addition, if composed of a flammable substance (such as flour or coal dust), under some circumstances it can be an explosion hazard.

Dust is responsible for the lung disease known as Pneumoconiosis, including black lung disease that occurs among coal miners. These dangers have resulted in a number of laws regulating environmental standards for working conditions.

1 House dust
2 Dust in outer space
3 Dust in fiction
4 Dust in religion
5 See also
6 Sources
7 Reference
8 External links

[edit] House dust

A sample of house dust and hair

Dust in homes, offices, and other human environments is mainly generated by the inhabitants, and mainly from their skin cells that slough off. Some atmospheric dust from the outdoors is also present. On average, approximately 6 mg/m²/day^[1] of house dust is formed in private households, depending primarily on the amount of time spent at home. "Dust bunnies" are little clumps of fluff that form when sufficient dust accumulates.

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 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. Once outside, dust particles are borne away by the breeze or disintegrated by sunlight. 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 coming in.

House dust mites 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. House dust can be removed by as many as ten methods listed hence: wiping, swiping or sweeping with a hand, a dust cloth, sponge, duster or a broom; or by suction from a vacuum cleaner or air filter. Dust is trapped by the device being used, however some becomes airborne and may come to settle in the cleaner's lungs, thus making the activity somewhat hazardous.

[edit] 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 comets 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 that can cover almost the entire planet. Interstellar dust is found between the stars, and high concentrations can produce diffuse nebula and reflection nebula.

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, which flew past the comet Wild 2 in 2004 and returned a capsule of the remains of the comet to the U.S. in January 2006. The Japanese Hayabusa spacecraft is currently on a mission to collect samples of dust from the surface of an asteroid.

[edit] Dust in fiction

In Philip Pullman's bestselling series His Dark Materials, dust (or "Dust", as it is spelled in the books) plays an important part by creating a connection between different worlds.

In the TV comedy Little Britain, Fat Fighters group leader Marjorie Dawes distinctively instructs the dieters to eat dust as it is "low in fat".

In JM Barrie's children's novel Peter Pan, "pixie dust" is a substance used to help create magical effects.

In Clark Ashton Smith's short horror story "The Treader In The Dust" [1], a scholar unwittingly calls forth a demon which personifies dustiness.

In Hal Clement's short science fiction story "Dust Rag", two astronauts struggle with dust that stuck to their helmets, blinding them.

[edit] Dust in religion

In the Bible:

In Genesis 3:19, God—following The Fall, Adam and Eve's transgression—states to the couple (representing humanity):

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.