- Related Topics:
- Earth
- Harmattan
- dust devil
- cryoconite
- dust storm
Dust
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What is dust?
Dust consists of microscopic, powder-like particles from various sources like sand, soil, organic tissue, and manufactured materials. Dust is ubiquitous both indoors and outdoors, found suspended in the air and collected on surfaces.
Inorganic components include rock bits, salts, and pollutants (insecticides and fumes from heavy metals). Organic components include pet dander, hair, skin fragments, textile fibers, ash, pollen, mites, and mold spores. Indoor dust can also contain mold colonies, paint shreds, soot, cloth fibers, and dangerous pollutants like DDT.
Dust particles play critical roles in weather by acting as condensation surfaces for raindrops and snowflakes and reflecting sunlight, which slows the Earth’s surface heating. However, dust can cause lung and respiratory disorders, such as pneumoconiosis, asthma, and farmer’s lung.
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Where can dust be found?
Dust is commonly found in both natural and human environments. It is present in the air and gathers on nearly every surface, including plants, animals, cultivated and uncultivated ground, furniture, and other indoor items.
Dust can also be found at interstellar scales, such as in planetary rings like those around Saturn and in the clouds that create nebulae and galaxies. Indoor dust can include outdoor dirt and air pollution tracked inside, mold colonies, paint fragments, soot, cloth fibers, and dangerous chemical pollutants.
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What is dust made of?
Dust is generally any microscopic particle light enough to be carried by the wind and heavy enough to be deposited on a surface.
Dust can be inorganic or organic. Inorganic components include bits of rock, salts, and pollutants like insecticides and fumes from heavy metals. Organic components include pet dander, hair, skin fragments, textile fibers, ash, pollen, mites, and mold spores. Dangerous chemical pollutants, such as the toxic insecticide DDT, have persisted in U.S. household dust as recently as 2022.
Household dust often contains dirt and pollen tracked in from outdoors. Research suggests that about two-thirds of household dust comes from outdoor sources, while the remaining one-third comes from indoor inorganic sources. Human skin cells and hair make up a significant portion of indoor dust.
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How does dust get into homes and buildings?
Dust enters homes and buildings through various means. Outdoor sources like dirt, pollen, and air pollution can be carried inside when doors are opened. Indoor sources, such as mold, paint shreds, soot, and textile fibers from clothing and furniture, also contribute to dust accumulation.
Human skin cells and hair are significant components of indoor dust, with each person shedding around 500 million skin cells daily. Pet fur, dander, and feathers can also add to the mix, and homes with dogs tend to have more bacteria in their dust. Dust can contain inorganic components, including rock particles, salts, and pollutants.
Ventilation systems, whether natural or mechanical, play a role in the movement and distribution of dust within enclosed spaces.
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Why can dust sometimes be harmful to people?
Dust can be harmful because the human body is unable to filter out the smallest particles, which can then lodge in the lungs and enter the circulatory system. Inhaling dust can lead to several lung and respiratory disorders, with symptoms and severity depending on the size and composition of the dust particles, the amount of dust inhaled, and the length of exposure.
Some dusts, such as pollen, skin fragments, and mold spores, can trigger allergic reactions and asthma. Other mineral dusts can cause lung diseases known as pneumoconioses, resulting in decreased exercise capacity, breathlessness, and respiratory difficulty. Additionally, dust can carry heavy metals, viruses, and bacteria into the lungs and bloodstream. Soot and tobacco smoke particles in dust are known to cause cancer and increase the risk of heart attack and stroke.
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How does dust affect the environment and Earth's atmosphere?
Dust, composed of various microscopic particles, significantly impacts the environment and Earth's atmosphere. Dust particles in the atmosphere can act as condensation surfaces for raindrops and snowflakes, playing a crucial role in cloud formation and precipitation.
In larger concentrations, dust reflects incoming sunlight, reducing the amount of heat absorbed by Earth's surface. However, dust can also cause respiratory disorders when inhaled, with smaller particles potentially leading to lung and heart issues. Indoor dust, which contains outdoor pollutants, chemical compounds, mold, and fibers, can pose health risks.
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Dust, in general, any microscopic, powderlike particle or collection of powderlike particles that is made up of sand, soil, fragments of organic tissue or manufactured materials, or some combination of these sources and is both light enough to be carried by the wind and heavy enough to be deposited on a surface. Individual dust particles can be large enough to be observed by the unaided eye, and large concentrations of dust driven by wind are often conspicuous as dust devils and dust storms, which can impair normal visibility and make breathing difficult. Inorganic components of dust include small bits of rock, salts, and pollutants, such as insecticides and fumes given off by heavy metals such as copper, iron, and mercury. Organic components include pet dander, hair or fur, skin fragments, textile fibers, and ash—as well as tiny living things such as pollen, mites, and mold spores.
Dust is ubiquitous in natural and human settings. It is suspended in the air and collects on virtually all surfaces, including the surfaces of individual plants, between hairlike structures of animals, and on the ground in cultivated and uncultivated landscapes, as well as on furniture and other elements of the indoor environment. Suspended dust that floats gently in the air may be almost imperceptible unless light from a sunbeam reflects off individual particles. In contrast, volcanic dust, which is ejected as part of a plume of larger particles during an eruption, and walls of dust, such those originating in the Sahara that are transported hundreds of kilometers over the Atlantic Ocean, are large enough to be seen from space (see also harmattan). At interstellar scales, large concentrations of dust particles make up planetary rings, such as those encircling Saturn, and the clouds that form nebulae and galaxies.
In addition, dust particles and other aerosols aloft perform critical roles in weather. Most importantly, they serve as condensation surfaces that facilitate the formation and growth of raindrops and snowflakes. In larger concentrations, dust particles help reflect incoming sunlight back into space, which slows the heating of Earth’s surface. Plumes of Saharan dust over the Atlantic Ocean have even been shown to inhibit the development of tropical cyclones.
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Particle size
Dust particles range in size from 1 to 400 micrometers (μm; 1 μm = 0.001 mm [about 0.00004 inch]). Particles larger than about 100 μm (0.1 mm [0.004 inch]), which is about the width of a human hair, are visible to the unaided eye. Human lungs are capable of filtering out particles as small as 1 μm. However, smaller particles—which include allergens, some types of smoke and ash particles, soot, and dust that remains suspended in the air—can lodge in the lungs and enter the circulatory system.
The inhalation of dust is responsible for a number of lung and respiratory disorders, whose symptoms and severity depend on the particles’ composition and size, the amount of dust inhaled, and the length of exposure. Larger allergens, such as pollen (which ranges in size from 20 to 100 μm), skin fragments (which range in size from 1 to 40 μm), and mold spores (which range in size from 3 to 10 μm), can trigger allergic reactions and asthma. In addition, lung diseases known as the pneumoconioses result when certain inhaled mineral dusts are deposited in the lungs, where they cause a chronic fibrotic reaction that leads to decreasing capacity for exercise and increasing breathlessness, cough, and respiratory difficulty. Such larger particles can deliver into the lungs smaller agents, such as heavy metals, viruses, and bacteria, which can later enter the bloodstream. Soot and tobacco smoke particles (which range in size from 0.01 to 0.15 μm and from 0.01 to 1 μm, respectively), known for their ability to cause cancer and raise the risk of heart attack and stroke in human beings, are small enough to easily pass the body’s blood-gas barrier.
Indoor dust
Within the household, opening the door and entering from the outdoors can ferry dirt and pollen to join the dust accumulating inside. Some research suggests that about two-thirds of household dust comes from outdoor sources such as outdoor dust and air pollution, while the remaining one-third derives from indoor inorganic sources. Along with these main elements of dust, all manner of other chemical compounds tend to show up in the mix. Other components of dust include colonies of mold, shreds of paint, and traces of soot. Dust also contains small fibers of cloth pulled from clothes and furniture. Dangerous chemical pollutants, such as the toxic insecticide DDT, have persisted in U.S. household dust as recently as 2022. Though DDT was banned in most countries in the 1970s due to its dangerous properties, the insecticide has persisted in nature and in households, where it may endanger children and other vulnerable groups.
While human skin cells and hair are not the only component of indoor dust, these materials do make up a significant portion of the mixture. Each human sheds about 500 million skin cells per day. Estimates of the percentage of dust composed of flakes of human skin vary, one study placing the figure as high as 75 to 90 percent. However, the portion of dust derived from living things does not necessarily come from humans alone. Traces of fur, dander, and feathers from pets add to the mix. Such cast-off cells are not the only contribution pets make to dust in the house. Research has indicated that households with dogs have more types of bacteria in their dust than pet-free households do. Other biotic substances, such as small living and dead insects, can also appear in dust. Dust mites, household pests that live in dust, can cause allergies.
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