The dust consists of Fiber S and remains fine, enough light to be put suspended in the air, or more generally, of particulate materials of a diameter lower than 500 micrometers. It can pose serious problems for the Santé of the men and the animals.

Its quality evolves/moves with the times. The dust Fossile S studied in the old samples of Poumon S of died of the London smog shows a dust primarily resulting from combustion of the coal, whereas one finds today there a number much more diversified pollutants, and to particles of metals of the group of the Platine lost by the catalytic pots whose object is to purify the air.

Dust is present in space, and is already studied on some planets or their satellites (of which the the Moon). On Ground, it is naturally present in the atmosphere, in proportions very varied according to the season and the biogeographic context .

In the external environment

It comes from varied, natural and anthropic sources, of which the erosion of the ground, the volcanic eruptions, marine spray, dust or sandstorms even after the storms. It is one of the components of the Pollution urban or resulting from the chimneys and the mufflers. It can also have for origin forest fires and the storms which sweep the arid or vulnerable grounds weakened by the ploughings, the abuses pesticides and artificial fertilizers or the overexploitation of the ground.

In the interior environment

Dust is present in great quantity in the dwellings, offices, factories, vehicles where it is put in suspension and is transported by flows of air (draft, turbulences induced by the movement of objects, animals or people, or the exposure of an object covered with dust to the Sun). It tends, by phenomena related to the molecular weight of its components, their more or less hygrophile nature and with the static electricity, and according to the hygroscopy, to settle on the objects (movable, objects of decorations…), or to agglomerate in “ sheep ” or minoux of dust under and behind the pieces of furniture. The content of the air of dust increases with the dryness of the air.

Dust and health

Several main issues are induced by dust.

Around urban industrial sites or, or near corridors of transport, or in buildings built with toxic materials (lead, asbestos.) dust often contains a significant proportion of toxins which are inhaled, in particular by the children who are more active and inspire proportionally more air than an adult (compared to their body mass). In these same zones, the air is often Acide, richer in Ozone and other gases aggressive Polluant S for the lungs, which supports phenomena of synergy.

Even when dust is not toxic, their chronic inhalation induced of the Cancer S (cancer of the miller, the baker which inhaled much the flour for example, or of the carpenter exposed to the fine sawdusts and dust of sandpapering). One of the causes of the Silicose is the inhalation of dust of coal or Schiste, worsened by the inhalation of pollutants, of which the Radon, a little mercury, or Radionucléide S in certain mines (of Uranium for example).

Dust contains Spore S of Mushroom S, of foams, of Fern S and Pollen S possibly naturally Allergen S and/or in the case of many pollens, which becomes it while being degraded in the urban environments where they are not carried any more by the Abeille S, nor trapped and degraded in the vegetalized grounds which are rare there. Pollens downtown are exposed to pollutants and phenomena of abrasion which degrade to them cuticule external and by updating molecules allergens not entering normally in contact with the mucous membranes (eye, nasal cavity, stop, lung…).

Dust is the support many Microbe S and other agents Pathogène S which cannot live a long time suspended in the air, but remains in dust.

The dust deposited by the soles of shoes pleasing in the houses of the remainders of excrements of dogs, cats, birds, rats, etc Of the toxic, radioactive particles contaminant can be brought to the residence with the working clotheses by those whose trade exposes them to a polluted environment.

Dust of organic origin (resulting for example from the degradation of feathers or the exfoliation of our Peau contains Acarien S whose excrements can be very allergens for the sensitive people.

This is why hygiene wants that one operates in clean rooms, that one tracks dust in the hospitals and the places of care, particularly around the allergic ones (asthmatic in particular). Masks with dust of the type FFP1, FFP2, or FFP3 (most effective) can protect the workers and the handymen. Filters can remove the air from the coarsest dust or finer dust (filtration by wet process, or electrostatic, or by passage through a dense fibrous mass).

The rates of dust contamination are naturally very low in the mediums vegetalized thanks to the dew, with foams and Lichen S which effectively traps great quantities of dust. They are snow, the rain, the fog and drizzles which wash the air of dust that it contains. Those Ci can contribute besides to nucléer the water drops and to make rain (sulfur particles, or certain bacteria of the kind Pseudomonas in particular).

  • architecture HQE in particular aims at reducing the factors of dust contamination of the air.

  • In the circumpolar zones where the summers can be dry, salting is sometimes used in summer to stabilize dust on the roads, thanks to the hygroscopic character of salt, but this salt ends up accumulating and poses problems of toxicity for the flora and certain animals (fish and some Amphibien S in particular).

Other effects induced by dust.

According to certain researchers of the Université of Bristol-board and University College of London in England, the exposure to a certain species of bacteria present in dust would act on our mental health. These bacteria (mycobacteries vaccae) have an effect similar to the antidepressants by stimulating in the brain the production of Sérotonine, the neuro-transmitter which makes that in the event of lack one plunges in depression. These studies undertaken on rodents, make it possible to better include/understand the role of certain dust on the immune system of the living beings.

Symbolic system

Symbolically, the word dust indicates sometimes the Déchet, or a negligible quantity, with a possible negative connotation. What recalls to the catholics the ritual formula Ash Wednesday “Remember that you are dust and that you will turn over in dust”

Measure dust contamination

  • the apparatus which is used to measure the dust contamination of the grounds calls the Bassoumètre . The networks of alarm and measurement of the quality of the air have also used for a few decades in outside of the gauges Owen which passively collect the deposits of dust, which one can then analyze samples, knowing that a biodegradable fraction will be able to have disappeared, and that bacteria could be themselves multiplied there if the times of analysis are important.

  • the Laser (Lidar) can be used to measure the content of the air of particles, remotely.
  • a simple filter upstream of a pump whose air flow is known allows simple quantitative measurements.

A person suffering from the Phobie of dust is known as amatophobe or koniphobe.

Study of dust

The study of dust can be made way Pluridisciplinaire:

Biology

Microbe S and the Acarien S are present and sometimes abundant in dust, and the Allergie S which they generate are increasingly frequent.

Chemistry

Dust is organic particles (Suie S, Pollen S, Poil S) or mineral (eroded rocks by the Vent) which can be analyzed.

Anecdote

We know that water freezes with zero centigrade degree. This phenomenon is related to the presence of dust. Indeed in “sterile” conditions (dustfree), water does not freeze, even up to -20 degrees and can remain in metastable balance until one introduces there an impurity or a crystal of ice. This phenomenon of Surfusion is completely comparable with that of supersaturation of the very pure air in which the steam in excess does not condense until it appears there centers of nucleation (principle of the Cloud chamber)

This phenomenon was illustrated by a famous anecdote which has occurred during the winter 1942 in Russia. It is about the episode of the horses of the Lac Ladoga during which a thousand of these animals were retouvèrent trapped in a gangue of ice, which had with the phenomenon of Surfusion.

See too

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