Dust is made of fine particles of solid matter. [1] On Earth, it generally consists of particles in the atmosphere that come from various sources such as soil lifted by wind (an aeolian process), volcanic eruptions, and pollution.
Dust in homes is composed of about 20–50% dead skin cells. [2] The rest, and in offices and other built environments, is composed of small amounts of plant pollen, human hairs, animal fur, textile fibers, paper fibers, minerals from outdoor soil, burnt meteorite particles, and many other materials which may be found in the local environment. [3]
Atmospheric or wind-borne fugitive dust, also known as aeolian dust, comes from dry regions where high-speed winds can remove mostly silt-sized material, abrading susceptible surfaces. This includes areas where grazing, ploughing, vehicle use, and other human behaviors have further destabilized the land, though not all source areas have been largely affected by anthropogenic impacts. [4] Dust-producing surfaces cover one-third of the global land area. These are made up of hyper-arid regions like the Sahara, which covers 0.9 billion hectares, and drylands, which occupy 5.2 billion hectares. [5]
Dust in the atmosphere is produced by saltation and abrasive sandblasting of sand-sized grains, and it is transported through the troposphere. 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, cause ocean cooling, and alter rainfall amounts. [4]
Dust in the Middle East has been a historic phenomenon. Recently, because of climate change 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.
The dust in Iraq and Iran are migratory systems that move from west to east or east to west in the spring and have the highest intensity, concentration, and extent until mid-summer. The causes of their occurrence are the lack of humidity, dry environment, low rainfall, and annual droughts. Due to the decrease of rainfall in areas such as Iraq and Syria, most of the dust in Iran also originates from the regions of Iraq, Syria, and Jordan. [6]
In addition to the foreign foci, there are areas inside the country that have either formed new dust foci in recent years or were from the past and their extent has increased. Among these areas, parts of southern Tehran, south of Alborz province – which in the past were plains, riverbeds, seasonal lakes, and seasonal reservoirs – and Gavkhoni wetland of Isfahan province can be mentioned because they have become dry and prone to dust. Among other areas that have become dust centers, Qom province, the Qom salt lake and its surroundings can be mentioned, as well as the Urmia lake, which due to strong winds and due to the dryness of the lake and the reduction of its size, some areas of its bed which were underwater in the past are subject to wind erosion. [6]
In Iran, the dust directly affects more than 5 million people and has become a serious government issue recently. In the Khuzestan province, it has led to the severe increase of air pollution. The amount of pollutants 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 study dust in the Middle East directly.[ citation needed ]
The continuation of drought has caused water scarcity or drying up of some wetlands and lakes such as Hamon and Urmia Lake. This has turned them into centers of dust. [6]
Director General of the Office of Desert Affairs of Iran's Natural Resources and Watershed Organization stated that according to the data of the 2018 studies, 30 million hectares of land in the country are affected by wind erosion, and 14 million hectares of this area are considered to be the focal points of wind erosion, which causes serious damage to infrastructure. [7]
Dust kicked up by vehicles traveling on roads is a significant source of harmful air pollution. [8] Road dust consists of deposits of vehicle and industrial exhaust gas, particles from tire and brake wear, dust from paved roads or potholes, and dust from construction sites. Road dust is a significant contributor to the generation and release of particulates into the atmosphere. [9] 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, vehicles equipped with vacuum cleaners, [10] vegetable oil sprays, [11] or with water sprayers. Calcium chloride 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 dust is responsible for the respiratory disease known as pneumoconiosis, including coal worker's pneumoconiosis disease that occurs among coal miners. 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. These circumstances are typically within confined spaces.
Most governmental Environmental Protection Agencies, including the United States Environmental Protection Agency (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:[ citation needed ]
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,[ citation needed ] including paving or laying down gravel, or stabilizing the surface with water, vegetable oils [11] or other dust suppressants, or by using water misters to suppress dust that is already airborne.[ citation needed ]
Dust control is the suppression of solid particles with diameters less than 500 micrometers (i.e. half a millimeter). Dust poses a health risk to children, [12] 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 tends to agitate the dust so it lands elsewhere[ citation needed ].
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 filters 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). [13]
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 [ citation needed ]. A reduced tacticity 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 or sealant to vulnerable edges and joins.
Cosmic dust is widely present in outer space, 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 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 which cover almost the entire planet. Interstellar dust is found between the stars, and high concentrations produce diffuse nebulae 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. [14]
Dust samples returned from outer space have provided information about conditions of the early solar system. Several spacecraft have sought to gather samples of dust and other materials. Among these craft was Stardust, which flew past 81P/Wild in 2004, and returned a capsule of the comet's remains to Earth. [15] In 2010 the Japanese Hayabusa spacecraft returned samples of dust from the surface of an asteroid. [16]
House dust mites are present indoors wherever humans live. [17] Positive tests for dust mite allergies are extremely common among people with asthma. Dust mites are microscopic arachnids whose primary food is dead human skin cells, but they do not live on living people. [18] They and their feces and other allergens 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). [17] It could take between twenty minutes and two hours for dust mites to settle back out of the air.
Dust mites are a nesting species that prefer a dark, warm, and humid climate. They flourish in mattresses, bedding, upholstered furniture, and carpets. [19] Their feces include enzymes 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. [20] House dust mites did not become a problem until humans began to use textiles, such as western style blankets and clothing. [21]
A vacuum cleaner, also known simply as a vacuum, is a device that uses suction, and often agitation, in order to remove dirt and other debris from carpets and hard floors.
A dust storm, also called a sandstorm, is a meteorological phenomenon common in arid and semi-arid regions. Dust storms arise when a gust front or other strong wind blows loose sand and dirt from a dry surface. Fine particles are transported by saltation and suspension, a process that moves soil from one place and deposits it in another.
Toner is a powder mixture used in laser printers and photocopiers to form the text and images on paper, in general through a toner cartridge. Mostly granulated plastic, early mixtures added only carbon powder and iron oxide; now there are mixtures that contain polypropylene, fumed silica, and various minerals for triboelectrification. Toner using plant-derived plastic also exists as an alternative to petroleum plastic. Toner particles are melted by the heat of the fuser, and are thus bonded to the paper.
HEPA filter, also known as a high efficiency particulate arresting filter, is an efficiency standard of air filters.
Haze is traditionally an atmospheric phenomenon in which dust, smoke, and other dry particulates suspended in air obscure visibility and the clarity of the sky. The World Meteorological Organization manual of codes includes a classification of particulates causing horizontal obscuration into categories of fog, ice fog, steam fog, mist, haze, smoke, volcanic ash, dust, sand, and snow. Sources for particles that cause haze include farming, traffic, industry, windy weather, volcanic activity and wildfires. Seen from afar and depending on the direction of view with respect to the Sun, haze may appear brownish or bluish, while mist tends to be bluish grey instead. Whereas haze often is considered a phenomenon occurring in dry air, mist formation is a phenomenon in saturated, humid air. However, haze particles may act as condensation nuclei that leads to the subsequent vapor condensation and formation of mist droplets; such forms of haze are known as "wet haze".
An air purifier or air cleaner is a device which removes contaminants from the air in a room to improve indoor air quality. These devices are commonly marketed as being beneficial to allergy sufferers and asthmatics, and at reducing or eliminating second-hand tobacco smoke.
A particulate air filter is a device composed of fibrous, or porous materials which removes particulates such as smoke, dust, pollen, mold, viruses and bacteria from the air. Filters containing an adsorbent or catalyst such as charcoal (carbon) may also remove odors and gaseous pollutants such as volatile organic compounds or ozone. Air filters are used in applications where air quality is important, notably in building ventilation systems and in engines.
An electrostatic precipitator (ESP) is a filterless device that removes fine particles, such as dust and smoke, from a flowing gas using the force of an induced electrostatic charge minimally impeding the flow of gases through the unit.
A dust collector is a system used to enhance the quality of air released from industrial and commercial processes by collecting dust and other impurities from air or gas. Designed to handle high-volume dust loads, a dust collector system consists of a blower, dust filter, a filter-cleaning system, and a dust receptacle or dust removal system. It is distinguished from air purifiers, which use disposable filters to remove dust.
Air pollution in Hong Kong is considered a serious problem. In 2004, visibility was less than eight kilometers for 30 per cent of the year. Cases of asthma and bronchial infections have soared due to reduced air quality. However, in recent years, the hours of reduced visibility in Hong Kong have decreased by significant amounts compared to the previous ten years.
Bioaerosols are a subcategory of particles released from terrestrial and marine ecosystems into the atmosphere. They consist of both living and non-living components, such as fungi, pollen, bacteria and viruses. Common sources of bioaerosols include soil, water, and sewage.
A concrete grinder is an abrasive machine for grinding and polishing concrete and natural stone. Concrete grinders can come in many configurations, the most common being a hand-held general purpose angle grinder, but it may be a specialized tool for countertops or floors. Angle grinders are small and mobile, and allow one to work on harder to reach areas and perform more precise work.
A hypoallergenic vacuum cleaner is a vacuum cleaner with filters designed to retain the vast majority of particles within the vacuum system. If successful this retention would greatly reduce the amount of potential allergens in the environment in which it is used. Regular vacuum cleaners are unable to retain most very fine dust and many allergens which simply are too small for the system to trap and are released from the system along with the exhaust air.
Particulates or atmospheric particulate matter are microscopic particles of solid or liquid matter suspended in the air. The term aerosol refers to the particulate/air mixture, as opposed to the particulate matter alone, though it is sometimes defined as a subset of aerosol terminology. Sources of particulate matter can be natural or anthropogenic. They have impacts on climate and precipitation that adversely affect human health, in ways additional to direct inhalation.
The clean air delivery rate (CADR) is a figure of merit that is the cubic feet per minute (CFM) of air that has had all the particles of a given size distribution removed. For air filters that have air flowing through them, it is the fraction of particles that have been removed from the air, multiplied by the air flow rate through the device. More precisely, it is the CFM of air in a 1,008-cubic-foot (28.5 m3) room that has had all the particles of a given size distribution removed from the air, over and above the rate at which the particles are naturally falling out of the air. Different filters have different abilities to remove different particle distributions, so three CADR's for a given device are typically measured: smoke, pollen, and dust. By combining the amount of airflow and particle removal efficiency, consumers are less likely to be misled by a high efficiency filter that is filtering a small amount of air, or by a high volume of air that is not being filtered very well.
A fan filter unit (FFU) is a type of motorized air filtering equipment. It is used to supply purified air to cleanrooms, laboratories, medical facilities or microenvironments by removing harmful airborne particles from recirculating air. The units are installed within the system's ceiling or floor grid. Large cleanrooms require a proportionally large number of FFUs, which in some cases may range from several hundred to several thousand. Units often contain their own pre-filter, HEPA filter and internally controllable fan air distribution.
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 is known as a dust cloud, and a large dust cloud driven by a gust front is known as a dust storm.
Bulldust or bull dust is a fine, soft and powdery red aeolian dust that is common across Australia, especially in the Outback and desert. Bulldust is a type of fugitive dust that when disturbed can have dangerous effects. Bulldust is common on remote roads, especially in the far north of Australia where the wet and dry season can cause the roads to either be boggy or very dry. Bulldust is also an Australian colloquial term and euphemism. Both meanings of the term originated in the 1920s.
Rubber pollution, similar to plastic pollution, occurs in various environments, and originates from a variety of sources, ranging from the food industry processing chain to tire wear. Synthetic and natural rubber dust and fragments now occur in food, airborne as particulates in air pollution, hidden in the earth as soil pollution, and in waterways, lakes and the sea.
Particulate pollution is pollution of an environment that consists of particles suspended in some medium. There are three primary forms: atmospheric particulate matter, marine debris, and space debris. Some particles are released directly from a specific source, while others form in chemical reactions in the atmosphere. Particulate pollution can be derived from either natural sources or anthropogenic processes.
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Dust mites in the humid atmosphere of Bangalore trigger around 60% of asthma