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Smoke from a fire Ognisko ubt 0126.jpeg
Smoke from a fire
Billowing smoke at Takaosan Yakuoin Temple firewalking festival in Japan, 2016
Smoke from a bee smoker, used in beekeeping Bee smoker02.jpg
Smoke from a bee smoker, used in beekeeping
Chemical composition distribution of volatile organic compounds released in smoke from a variety of solid fuels Smoke chemical composition.jpg
Chemical composition distribution of volatile organic compounds released in smoke from a variety of solid fuels
Volatility distribution of volatile organic compound emissions in wood smoke Wood Volatility Basis Dataset.jpg
Volatility distribution of volatile organic compound emissions in wood smoke
Smoke being emitted from a lit cigarette Lit cigarette.jpg
Smoke being emitted from a lit cigarette
Oil fires and smoke, after Iraqi forces set fire to oil wells during the First Gulf War KuwaitiOilFires-STS037-152-91-(2).jpg
Oil fires and smoke, after Iraqi forces set fire to oil wells during the First Gulf War

Smoke is a suspension [3] of airborne particulates and gases [4] emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass. It is commonly an unwanted by-product of fires (including stoves, candles, internal combustion engines, oil lamps, and fireplaces), but may also be used for pest control (fumigation), communication (smoke signals), defensive and offensive capabilities in the military (smoke screen), cooking, or smoking (tobacco, cannabis, etc.). It is used in rituals where incense, sage, or resin is burned to produce a smell for spiritual or magical purposes. It can also be a flavoring agent and preservative.


Smoke from a grassland fire in Northern Mexico during a heat wave occurring at the same time as the forest fire season in Mexico. Black Fire Smoke during a Heat Wvae.jpg
Smoke from a grassland fire in Northern Mexico during a heat wave occurring at the same time as the forest fire season in Mexico.

Smoke inhalation is the primary cause of death in victims of indoor fires. The smoke kills by a combination of thermal damage, poisoning and pulmonary irritation caused by carbon monoxide, hydrogen cyanide and other combustion products.

Smoke is an aerosol (or mist) of solid particles and liquid droplets that are close to the ideal range of sizes for Mie scattering of visible light. [5]

Chemical composition

The composition of smoke depends on the nature of the burning fuel and the conditions of combustion. Fires with high availability of oxygen burn at a high temperature and with a small amount of smoke produced; the particles are mostly composed of ash, or with large temperature differences, of condensed aerosol of water. High temperature also leads to production of nitrogen oxides. [6] Sulfur content yields sulfur dioxide, or in case of incomplete combustion, hydrogen sulfide. [7] Carbon and hydrogen are almost completely oxidized to carbon dioxide and water. [8] Fires burning with lack of oxygen produce a significantly wider palette of compounds, many of them toxic. [8] Partial oxidation of carbon produces carbon monoxide, while nitrogen-containing materials can yield hydrogen cyanide, ammonia, and nitrogen oxides. [9] Hydrogen gas can be produced instead of water. [9] Contents of halogens such as chlorine (e.g. in polyvinyl chloride or brominated flame retardants) may lead to the production of hydrogen chloride, phosgene, dioxin, and chloromethane, bromomethane and other halocarbons. [9] [10] Hydrogen fluoride can be formed from fluorocarbons, whether fluoropolymers subjected to fire or halocarbon fire suppression agents. Phosphorus and antimony oxides and their reaction products can be formed from some fire retardant additives, increasing smoke toxicity and corrosivity. [10] Pyrolysis of polychlorinated biphenyls (PCB), e.g. from burning older transformer oil, and to lower degree also of other chlorine-containing materials, can produce 2,3,7,8-tetrachlorodibenzodioxin, a potent carcinogen, and other polychlorinated dibenzodioxins. [10] Pyrolysis of fluoropolymers, e.g. teflon, in presence of oxygen yields carbonyl fluoride (which hydrolyzes readily to HF and CO2); other compounds may be formed as well, e.g. carbon tetrafluoride, hexafluoropropylene, and highly toxic perfluoroisobutene (PFIB). [11]

Emission of soot in the fumes of a large diesel truck, without particle filters. Diesel-smoke.jpg
Emission of soot in the fumes of a large diesel truck, without particle filters.

Pyrolysis of burning material, especially incomplete combustion or smoldering without adequate oxygen supply, also results in production of a large amount of hydrocarbons, both aliphatic (methane, ethane, ethylene, acetylene) and aromatic (benzene and its derivates, polycyclic aromatic hydrocarbons; e.g. benzo[a]pyrene, studied as a carcinogen, or retene), terpenes. [12] It also results in the emission of a range of smaller oxygenated volatile organic compounds (methanol, acetic acid, hydroxy acetone, methyl acetate and ethyl formate) which are formed as combustion by products as well as less volatile oxygenated organic species such as phenolics, furans and furanones. [1] Heterocyclic compounds may be also present. [13] Heavier hydrocarbons may condense as tar; smoke with significant tar content is yellow to brown. [14] Combustion of solid fuels can result in the emission of many hundreds to thousands of lower volatility organic compounds in the aerosol phase. [15] Presence of such smoke, soot, and/or brown oily deposits during a fire indicates a possible hazardous situation, as the atmosphere may be saturated with combustible pyrolysis products with concentration above the upper flammability limit, and sudden inrush of air can cause flashover or backdraft. [16]

Presence of sulfur can lead to formation of gases like hydrogen sulfide, carbonyl sulfide, sulfur dioxide, carbon disulfide, and thiols; especially thiols tend to get adsorbed on surfaces and produce a lingering odor even long after the fire. Partial oxidation of the released hydrocarbons yields in a wide palette of other compounds: aldehydes (e.g. formaldehyde, acrolein, and furfural), ketones, alcohols (often aromatic, e.g. phenol, guaiacol, syringol, catechol, and cresols), carboxylic acids (formic acid, acetic acid, etc.).[ citation needed ]

The visible particulate matter in such smokes is most commonly composed of carbon (soot). Other particulates may be composed of drops of condensed tar, or solid particles of ash. The presence of metals in the fuel yields particles of metal oxides. Particles of inorganic salts may also be formed, e.g. ammonium sulfate, ammonium nitrate, or sodium chloride. Inorganic salts present on the surface of the soot particles may make them hydrophilic. Many organic compounds, typically the aromatic hydrocarbons, may be also adsorbed on the surface of the solid particles. Metal oxides can be present when metal-containing fuels are burned, e.g. solid rocket fuels containing aluminium. Depleted uranium projectiles after impacting the target ignite, producing particles of uranium oxides. Magnetic particles, spherules of magnetite-like ferrous ferric oxide, are present in coal smoke; their increase in deposits after 1860 marks the beginning of the Industrial Revolution. [17] (Magnetic iron oxide nanoparticles can be also produced in the smoke from meteorites burning in the atmosphere.) [18] Magnetic remanence, recorded in the iron oxide particles, indicates the strength of Earth's magnetic field when they were cooled beyond their Curie temperature; this can be used to distinguish magnetic particles of terrestrial and meteoric origin. [19] Fly ash is composed mainly of silica and calcium oxide. Cenospheres are present in smoke from liquid hydrocarbon fuels. Minute metal particles produced by abrasion can be present in engine smokes. Amorphous silica particles are present in smokes from burning silicones; small proportion of silicon nitride particles can be formed in fires with insufficient oxygen. The silica particles have about 10 nm size, clumped to 70–100 nm aggregates and further agglomerated to chains. [11] Radioactive particles may be present due to traces of uranium, thorium, or other radionuclides in the fuel; hot particles can be present in case of fires during nuclear accidents (e.g. Chernobyl disaster) or nuclear war.

Smoke particulates, like other aerosols, are categorized into three modes based on particle size:

Most of the smoke material is primarily in coarse particles. Those undergo rapid dry precipitation, and the smoke damage in more distant areas outside of the room where the fire occurs is therefore primarily mediated by the smaller particles. [20]

Aerosol of particles beyond visible size is an early indicator of materials in a preignition stage of a fire. [11]

Burning of hydrogen-rich fuel produces water vapor; this results in smoke containing droplets of water. In absence of other color sources (nitrogen oxides, particulates...), such smoke is white and cloud-like.

Smoke emissions may contain characteristic trace elements. Vanadium is present in emissions from oil fired power plants and refineries; oil plants also emit some nickel. Coal combustion produces emissions containing aluminium, arsenic, chromium, cobalt, copper, iron, mercury, selenium, and uranium.

Traces of vanadium in high-temperature combustion products form droplets of molten vanadates. These attack the passivation layers on metals and cause high temperature corrosion, which is a concern especially for internal combustion engines. Molten sulfate and lead particulates also have such effect.

Some components of smoke are characteristic of the combustion source. Guaiacol and its derivatives are products of pyrolysis of lignin and are characteristic of wood smoke; other markers are syringol and derivates, and other methoxy phenols. Retene, a product of pyrolysis of conifer trees, is an indicator of forest fires. Levoglucosan is a pyrolysis product of cellulose. Hardwood vs softwood smokes differ in the ratio of guaiacols/syringols. Markers for vehicle exhaust include polycyclic aromatic hydrocarbons, hopanes, steranes, and specific nitroarenes (e.g. 1-nitropyrene). The ratio of hopanes and steranes to elemental carbon can be used to distinguish between emissions of gasoline and diesel engines. [21]

Many compounds can be associated with particulates; whether by being adsorbed on their surfaces, or by being dissolved in liquid droplets. Hydrogen chloride is well absorbed in the soot particles. [20]

Inert particulate matter can be disturbed and entrained into the smoke. Of particular concern are particles of asbestos.

Deposited hot particles of radioactive fallout and bioaccumulated radioisotopes can be reintroduced into the atmosphere by wildfires and forest fires; this is a concern in e.g. the Zone of alienation containing contaminants from the Chernobyl disaster.

Polymers are a significant source of smoke. Aromatic side groups, e.g. in polystyrene, enhance generation of smoke. Aromatic groups integrated in the polymer backbone produce less smoke, likely due to significant charring. Aliphatic polymers tend to generate the least smoke, and are non-self-extinguishing. However presence of additives can significantly increase smoke formation. Phosphorus-based and halogen-based flame retardants decrease production of smoke. Higher degree of cross-linking between the polymer chains has such effect too. [22]

Visible and invisible particles of combustion

Smoke from a wildfire Wildfiretopanga.jpg
Smoke from a wildfire
Smoke rising up from the smoldering remains of a recently extingished mountain fire in South Africa. Muizenberg Mountian Fires in Cape Town of 2015.jpg
Smoke rising up from the smoldering remains of a recently extingished mountain fire in South Africa.

The naked eye detects particle sizes greater than 7 µm (micrometres). Visible particles emitted from a fire are referred to as smoke. Invisible particles are generally referred to as gas or fumes. This is best illustrated when toasting bread in a toaster. As the bread heats up, the products of combustion increase in size. The fumes initially produced are invisible but become visible if the toast is burnt.

An ionization chamber type smoke detector is technically a product of combustion detector, not a smoke detector. Ionization chamber type smoke detectors detect particles of combustion that are invisible to the naked eye. This explains why they may frequently false alarm from the fumes emitted from the red-hot heating elements of a toaster, before the presence of visible smoke, yet they may fail to activate in the early, low-heat smoldering stage of a fire.

Smoke from a typical house fire contains hundreds of different chemicals and fumes. As a result, the damage caused by the smoke can often exceed that caused by the actual heat of the fire. In addition to the physical damage caused by the smoke of a fire – which manifests itself in the form of stains – is the often even harder to eliminate problem of a smoky odor. Just as there are contractors that specialize in rebuilding/repairing homes that have been damaged by fire and smoke, fabric restoration companies specialize in restoring fabrics that have been damaged in a fire.


Smoke from oxygen-deprived fires contains a significant concentration of compounds that are flammable. A cloud of smoke, in contact with atmospheric oxygen, therefore has the potential of being ignited – either by another open flame in the area, or by its own temperature. This leads to effects like backdraft and flashover. Smoke inhalation is also a danger of smoke that can cause serious injury and death.[ citation needed ]

Processing fish while being exposed to smoke Fish processing hub.jpg
Processing fish while being exposed to smoke

Many compounds of smoke from fires are highly toxic and/or irritating. The most dangerous is carbon monoxide leading to carbon monoxide poisoning, sometimes with the additive effects of hydrogen cyanide and phosgene. Smoke inhalation can therefore quickly lead to incapacitation and loss of consciousness. Sulfur oxides, hydrogen chloride and hydrogen fluoride in contact with moisture form sulfuric, hydrochloric and hydrofluoric acid, which are corrosive to both lungs and materials. When asleep the nose does not sense smoke nor does the brain, but the body will wake up if the lungs become enveloped in smoke and the brain will be stimulated and the person will be awoken. This does not work if the person is incapacitated or under the influence of drugs and/or alcohol.[ citation needed ]

World Trade Center on fire after terrorists flew planes into the buildings on September 11, 2001 WTC smoking on 9-11.jpeg
World Trade Center on fire after terrorists flew planes into the buildings on September 11, 2001

Cigarette smoke is a major modifiable risk factor for lung disease, heart disease, and many cancers. Smoke can also be a component of ambient air pollution due to the burning of coal in power plants, forest fires or other sources, although the concentration of pollutants in ambient air is typically much less than that in cigarette smoke. One day of exposure to PM2.5 at a concentration of 880 μg/m3, such as occurs in Beijing, China, is the equivalent of smoking one or two cigarettes in terms of particulate inhalation by weight. [23] [24] The analysis is complicated, however, by the fact that the organic compounds present in various ambient particulates may have a higher carcinogenicity than the compounds in cigarette smoke particulates. [25] Secondhand tobacco smoke is the combination of both sidestream and mainstream smoke emissions from a burning tobacco product. These emissions contain more than 50 carcinogenic chemicals. According to the United States Surgeon General's 2006 report on the subject, "Short exposures to secondhand [tobacco] smoke can cause blood platelets to become stickier, damage the lining of blood vessels, decrease coronary flow velocity reserves, and reduce heart variability, potentially increasing the risk of a heart attack". [26] The American Cancer Society lists "heart disease, lung infections, increased asthma attacks, middle ear infections, and low birth weight" as ramifications of smoker's emission. [27]

Reduced visibility due to wildfire smoke in Sheremetyevo Airport, Moscow, 7 August 2010 Smoke from forest fires Sheremetyevo 20100807 01.JPG
Reduced visibility due to wildfire smoke in Sheremetyevo Airport, Moscow, 7 August 2010
Red smoke carried by a parachutist of the UK Lightning Bolts Army Parachute Display Team Red smoke from Army display parachutist landing 29Sept2018 arp.jpg
Red smoke carried by a parachutist of the UK Lightning Bolts Army Parachute Display Team

Smoke can obscure visibility, impeding occupant exiting from fire areas. In fact, the poor visibility due to the smoke that was in the Worcester Cold Storage Warehouse fire in Worcester, Massachusetts was the reason why the trapped rescue firefighters could not evacuate the building in time. Because of the striking similarity that each floor shared, the dense smoke caused the firefighters to become disoriented. [28]


Smoke can contain a wide variety of chemicals, many of them aggressive in nature. Examples are hydrochloric acid and hydrobromic acid, produced from halogen-containing plastics and fire retardants, hydrofluoric acid released by pyrolysis of fluorocarbon fire suppression agents, sulfuric acid from burning of sulfur-containing materials, nitric acid from high-temperature fires where nitrous oxide gets formed, phosphoric acid and antimony compounds from P and Sb based fire retardants, and many others. Such corrosion is not significant for structural materials, but delicate structures, especially microelectronics, are strongly affected. Corrosion of circuit board traces, penetration of aggressive chemicals through the casings of parts, and other effects can cause an immediate or gradual deterioration of parameters or even premature (and often delayed, as the corrosion can progress over long time) failure of equipment subjected to smoke. Many smoke components are also electrically conductive; deposition of a conductive layer on the circuits can cause crosstalks and other deteriorations of the operating parameters or even cause short circuits and total failures. Electrical contacts can be affected by corrosion of surfaces, and by deposition of soot and other conductive particles or nonconductive layers on or across the contacts. Deposited particles may adversely affect the performance of optoelectronics by absorbing or scattering the light beams.[ citation needed ]

Corrosivity of smoke produced by materials is characterized by the corrosion index (CI), defined as material loss rate (angstrom/minute) per amount of material gasified products (grams) per volume of air (m3). It is measured by exposing strips of metal to flow of combustion products in a test tunnel. Polymers containing halogen and hydrogen (polyvinyl chloride, polyolefins with halogenated additives, etc.) have the highest CI as the corrosive acids are formed directly with water produced by the combustion, polymers containing halogen only (e.g. polytetrafluoroethylene) have lower CI as the formation of acid is limited to reactions with airborne humidity, and halogen-free materials (polyolefins, wood) have the lowest CI. [20] However, some halogen-free materials can also release significant amount of corrosive products. [29]

Smoke damage to electronic equipment can be significantly more extensive than the fire itself. Cable fires are of special concern; low smoke zero halogen materials are preferable for cable insulation.[ citation needed ]

When smoke comes into contact with the surface of any substance or structure, the chemicals contained in it are transferred to it. The corrosive properties of the chemicals cause the substance or structure to decompose at a rapid rate. Certain materials or structures absorb these chemicals, which is why clothing, unsealed surfaces, potable water, piping, wood, etc., are replaced in most cases of structural fires.[ citation needed ]

Health effects of wood smoke

Wood smoke is a major source of air pollution, [30] [31] [32] [33] especially particulate pollution, [31] pollution by polycyclic aromatic hydrocarbons (PAHs) [34] and volatile organic compounds (VOCs) [31] [ better source needed ] such as formaldehyde. [35]

In the United Kingdom domestic combustion, especially for industrial uses, is the largest single source of PM2.5 annually. [36] [37] In some towns and cities in New South Wales, wood smoke may be responsible for 60% of fine particle air pollution in the winter. [38] A year-long sampling campaign in Athens, Greece found a third (31%) of PAH urban air pollution to be caused by wood-burning, roughly as much as that of diesel and oil (33%) and gasoline (29%). It also found that wood-burning is responsible for nearly half (43%) of annual PAH lung cancer-risk compared to the other sources and that wintertime PAH levels were 7 times higher than in other seasons, presumably due to an increased use of fireplaces and heaters. The largest exposure events are periods during the winter with reduced atmospheric dispersion to dilute the accumulated pollution , in particular due to the low wind speeds. [34]

Wood smoke (for example from wildfires) can cause lung damage, [39] [40] artery damage and DNA damage [41] leading to cancer, [42] [43] other respiratory and lung disease and cardiovascular disease. [38] [44] Air pollution, particulate matter and wood smoke may also indirectly cause brain damage because of particulates breaching the cardiovascular system and into the brain, [45] [46] [47] [48] which can increase the risk of developmental disorders, [49] [50] [51] [52] neurodegenerative disorders [53] [54] mental disorders, [55] [56] [57] and suicidal behavior, [55] [57] although studies on the link between depression and some air pollutants are not consistent. [58] At least one study has identified "the abundant presence in the human brain of magnetite nanoparticles that match precisely the high-temperature magnetite nanospheres, formed by combustion and/or friction-derived heating, which are prolific in urban, airborne particulate matter (PM)." [59] Air pollution has also been linked to a range of other psychosocial problems. [56]


As early as the 15th century Leonardo da Vinci commented at length on the difficulty of assessing smoke, and distinguished between black smoke (carbonized particles) and white 'smoke' which is not a smoke at all but merely a suspension of harmless water particulates. [60]

Smoke from heating appliances is commonly measured in one of the following ways:

In-line capture. A smoke sample is simply sucked through a filter which is weighed before and after the test and the mass of smoke found. This is the simplest and probably the most accurate method, but can only be used where the smoke concentration is slight, as the filter can quickly become blocked. [61]

The ASTM smoke pump is a simple and widely used method of in-line capture where a measured volume of smoke is pulled through a filter paper and the dark spot so formed is compared with a standard.

Filter/dilution tunnel. A smoke sample is drawn through a tube where it is diluted with air, the resulting smoke/air mixture is then pulled through a filter and weighed. This is the internationally recognized method of measuring smoke from combustion. [62]

Electrostatic precipitation. The smoke is passed through an array of metal tubes which contain suspended wires. A (huge) electrical potential is applied across the tubes and wires so that the smoke particles become charged and are attracted to the sides of the tubes. This method can over-read by capturing harmless condensates, or under-read due to the insulating effect of the smoke. However, it is the necessary method for assessing volumes of smoke too great to be forced through a filter, i.e., from bituminous coal.

Ringelmann scale. A measure of smoke color. Invented by Professor Maximilian Ringelmann in Paris in 1888, it is essentially a card with squares of black, white and shades of gray which is held up and the comparative grayness of the smoke judged. Highly dependent on light conditions and the skill of the observer it allocates a grayness number from 0 (white) to 5 (black) which has only a passing relationship to the actual quantity of smoke. Nonetheless, the simplicity of the Ringelmann scale means that it has been adopted as a standard in many countries.

Optical scattering. A light beam is passed through the smoke. A light detector is situated at an angle to the light source, typically at 90°, so that it receives only light reflected from passing particles. A measurement is made of the light received which will be higher as the concentration of smoke particles becomes higher.

Optical obscuration. A light beam is passed through the smoke and a detector opposite measures the light. The more smoke particles are present between the two, the less light will be measured.

Combined optical methods. There are various proprietary optical smoke measurement devices such as the 'nephelometer' or the 'aethalometer' which use several different optical methods, including more than one wavelength of light, inside a single instrument and apply an algorithm to give a good estimate of smoke. It has been claimed that these devices can differentiate types of smoke and so their probable source can be inferred, though this is disputed. [63]

Inference from carbon monoxide. Smoke is incompletely burned fuel, carbon monoxide is incompletely burned carbon, therefore it has long been assumed that measurement of CO in flue gas (a cheap, simple and very accurate procedure) will provide a good indication of the levels of smoke. Indeed, several jurisdictions use CO measurement as the basis of smoke control. However it is far from clear how accurate the correspondence is.

Medicinal smoking

Throughout recorded history, humans have used the smoke of medicinal plants to cure illness. A sculpture from Persepolis shows Darius the Great (522–486 BC), the king of Persia, with two censers in front of him for burning Peganum harmala and/or sandalwood Santalum album, which was believed to protect the king from evil and disease. More than 300 plant species in 5 continents are used in smoke form for different diseases. As a method of drug administration, smoking is important as it is a simple, inexpensive, but very effective method of extracting particles containing active agents. More importantly, generating smoke reduces the particle size to a microscopic scale thereby increasing the absorption of its active chemical principles. [64]

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Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combustion does not always result in fire, because a flame is only visible when substances undergoing combustion vaporize, but when it does, a flame is a characteristic indicator of the reaction. While the activation energy must be overcome to initiate combustion, the heat from a flame may provide enough energy to make the reaction self-sustaining.

<span class="mw-page-title-main">Hydrocarbon</span> Organic compound consisting entirely of hydrogen and carbon

In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic; their odor is usually faint, and may be similar to that of gasoline or lighter fluid. They occur in a diverse range of molecular structures and phases: they can be gases, liquids, low melting solids or polymers.

<span class="mw-page-title-main">Smog</span> Smoke-like, fog-like air pollutions

Smog, or smoke fog, is a type of intense air pollution. The word "smog" was coined in the early 20th century, and is a portmanteau of the words smoke and fog to refer to smoky fog due to its opacity, and odor. The word was then intended to refer to what was sometimes known as pea soup fog, a familiar and serious problem in London from the 19th century to the mid-20th century. This kind of visible air pollution is composed of nitrogen oxides, sulfur oxide, ozone, smoke and other particulates. Man-made smog is derived from coal combustion emissions, vehicular emissions, industrial emissions, forest and agricultural fires and photochemical reactions of these emissions.

<span class="mw-page-title-main">Pyrolysis</span> Thermal decomposition of materials at elevated temperatures in an inert atmosphere

The pyrolysis process is the thermal decomposition of materials at elevated temperatures, often in an inert atmosphere. It involves a change of chemical composition. The word is coined from the Greek-derived elements pyro "fire", "heat", "fever" and lysis "separating".

<span class="mw-page-title-main">Soot</span> Impure carbon particles resulting from the incomplete combustion of hydrocarbons

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<span class="mw-page-title-main">Polycyclic aromatic hydrocarbon</span> Hydrocarbon composed of multiple aromatic rings

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<span class="mw-page-title-main">Fireplace</span> Device for firing solid fuels in buildings

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<span class="mw-page-title-main">Diesel exhaust</span>

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Organic molecular tracers in pollution control and environmental science are referred to as organic molecular markers or emission markers, and are compounds or compound classes. These tracers are of interest in the field of air quality because they can help identify particulate emission sources, as they are relatively unique to those sources. This approach is generally applied to particulate matter under 2.5μm in diameter because of the formation mechanisms and the health risks associated with this size regime. With tracer compounds, the principles of mass balance are used to 'trace' emissions from the source to the receptor site where a sample is taken. Use of organic tracers has become more common as measurement quality has improved, costs have decreased, and compounds that were historically good tracers, such as lead, have decreased in ambient concentrations due to various factors including government regulation.

<span class="mw-page-title-main">Particulates</span> Microscopic solid or liquid matter suspended in the Earths atmosphere

Particulates – also known as atmospheric aerosol particles, atmospheric particulate matter, particulate matter (PM) or suspended particulate matter (SPM) – are microscopic particles of solid or liquid matter suspended in the air. The term aerosol commonly refers to the particulate/air mixture, as opposed to the particulate matter alone. 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.

<span class="mw-page-title-main">Air pollution in India</span> Air pollution in India

Air pollution in India is a serious environmental issue. Of the 30 most polluted cities in the world, 21 were in India in 2019. As per a study based on 2016 data, at least 140 million people in India breathe air that is 10 times or more over the WHO safe limit and 13 of the world's 20 cities with the highest annual levels of air pollution are in India. 51% of the pollution is caused by industrial pollution, 27 % by vehicles, 17% by crop burning and 5% by other sources. Air pollution contributes to the premature deaths of 2 million Indians every year. Emissions come from vehicles and industry, whereas in rural areas, much of the pollution stems from biomass burning for cooking and keeping warm. In autumn and spring months, large scale crop residue burning in agriculture fields – a cheaper alternative to mechanical tilling – is a major source of smoke, smog and particulate pollution. India has a low per capita emissions of greenhouse gases but the country as a whole is the third largest greenhouse gas producer after China and the United States. A 2013 study on non-smokers has found that Indians have 30% weaker lung function than Europeans.

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.


  1. 1 2 Stewart, Gareth J.; Acton, W. Joe F.; Nelson, Beth S.; Vaughan, Adam R.; Hopkins, James R.; Arya, Rahul; Mondal, Arnab; Jangirh, Ritu; Ahlawat, Sakshi; Yadav, Lokesh; Sharma, Sudhir K.; Dunmore, Rachel E.; Yunus, Siti S. M.; Hewitt, C. Nicholas; Nemitz, Eiko; Mullinger, Neil; Gadi, Ranu; Sahu, Lokesh K.; Tripathi, Nidhi; Rickard, Andrew R.; Lee, James D.; Mandal, Tuhin K.; Hamilton, Jacqueline F. (18 February 2021). "Emissions of non-methane volatile organic compounds from combustion of domestic fuels in Delhi, India". Atmospheric Chemistry and Physics. 21 (4): 2383–2406. Bibcode:2021ACP....21.2383S. doi: 10.5194/acp-21-2383-2021 .
  2. Stewart, Gareth J.; Nelson, Beth S.; Acton, W. Joe F.; Vaughan, Adam R.; Hopkins, James R.; Yunus, Siti S. M.; Hewitt, C. Nicholas; Nemitz, Eiko; Mandal, Tuhin K.; Gadi, Ranu; Sahu, Lokesh. K.; Rickard, Andrew R.; Lee, James D.; Hamilton, Jacqueline F. (2021). "Comprehensive organic emission profiles, secondary organic aerosol production potential, and OH reactivity of domestic fuel combustion in Delhi, India". Environmental Science: Atmospheres. 1 (2): 104–117. doi: 10.1039/D0EA00009D .
  3. "15.11: Colloids". Chemistry LibreTexts. 27 June 2016. Retrieved 23 November 2022.
  4. "Smoke Production and Properties" (PDF). SFPE Handbook of Fire Protection Engineering. Archived from the original (PDF) on 21 August 2008.
  5. The Virginia Journal of Science. Virginia Academy of Science. 1976.[ page needed ]
  6. Lee, C.C. (1 January 2005). Environmental Engineering Dictionary. Government Institutes. p. 528. ISBN   9780865878488.
  7. Carlone, Nancy (2009). Nancy Caroline's Emergency Care in the Streets, Canadian Edition. Burlington, Massachusetts: Jones & Bartlett Learning. pp. 20–28. ISBN   9781284053845.
  8. 1 2 Mauseth, James D. (1991). Botany: An Introduction to Plant Biology. Burlington, Massachusetts: Jones & Bartlett Learning. p. 234. ISBN   9780030938931.
  9. 1 2 3 Reuter, M.A.; Boin, U.M.J.; Schaik, A. van; Verhoef, E.; Heiskanen, K.; Yang, Yongxiang; Georgalli, G. (2 November 2005). The Metrics of Material and Metal Ecology. Amsterdam: Elsevier. ISBN   9780080457925.
  10. 1 2 3 Fardell, P.J. (1 January 1993). Toxicity of Plastics and Rubber in Fire. iSmithers Rapra Publishing. ISBN   978-1-85957-001-2.
  11. 1 2 3 National Research Council (U.S.). Task Force on Flammability, Smoke, Toxicity and Corrosive Gases of Electric Cable Materials (1978). Flammability, smoke, toxicity, and corrosive gases of electric cable materials: report of the Task Force on Flammability, Smoke, Toxicity, and Corrosive Gases of Electric Cable Materials, National Materials Advisory Board, Commission on Sociotechnical Systems, National Research Council. National Academies. pp. 107–. NAP:15488.{{cite book}}: CS1 maint: multiple names: authors list (link)
  12. Moldoveanu, S.C. (11 November 1998). Analytical Pyrolysis of Natural Organic Polymers. Elsevier. pp. 152, 428. ISBN   9780444822031.
  13. Moldoveanu, Serban (16 September 2009). Pyrolysis of Organic Molecules: Applications to Health and Environmental Issues. Elsevier. p. 643. ISBN   978-0444531131.
  14. Staff writer (1892). A dictionary of the coal tar colours. Heywood and Co. p. 8. ISBN   978-1409701699.
  15. Stewart, Gareth J.; Nelson, Beth S.; Acton, W. Joe F.; Vaughan, Adam R.; Farren, Naomi J.; Hopkins, James R.; Ward, Martyn W.; Swift, Stefan J.; Arya, Rahul; Mondal, Arnab; Jangirh, Ritu; Ahlawat, Sakshi; Yadav, Lokesh; Sharma, Sudhir K.; Yunus, Siti S. M.; Hewitt, C. Nicholas; Nemitz, Eiko; Mullinger, Neil; Gadi, Ranu; Sahu, Lokesh K.; Tripathi, Nidhi; Rickard, Andrew R.; Lee, James D.; Mandal, Tuhin K.; Hamilton, Jacqueline F. (18 February 2021). "Emissions of intermediate-volatility and semi-volatile organic compounds from domestic fuels used in Delhi, India". Atmospheric Chemistry and Physics. 21 (4): 2407–2426. Bibcode:2021ACP....21.2407S. doi: 10.5194/acp-21-2407-2021 .
  16. Fire, Frank L. (2009). The Common Sense Approach to Hazardous Materials. Fire Engineering Books. p. 129. ISBN   978-0912212111.
  17. Oldfield, F.; Tolonen, K. & Thompson, R. (1981). "History of Particulate Atmospheric Pollution from Magnetic Measurements in Dated Finnish Peat Profiles". Ambio. 10 (4): 185. JSTOR   4312673.
  18. Lanci, L.; Kent, D. V. (2006). "Meteoric smoke fallout revealed by superparamagnetism in Greenland ice". Geophysical Research Letters. 33 (13): L13308. Bibcode:2006GeoRL..3313308L. doi: 10.1029/2006GL026480 .
  19. Suavet, C.; Gattacceca, J.; Rochette, P.; Perchiazzi, N.; Folco, L.; Duprat, J.; Harvey, R. P. (4 April 2009). "Magnetic properties of micrometeorites" (PDF). Journal of Geophysical Research. 114 (B4): B04102. Bibcode:2009JGRB..114.4102S. doi:10.1029/2008JB005831.
  20. 1 2 3 Mark, James E. (2006). Physical properties of polymers handbook. Springer. ISBN   978-0-387-31235-4.
  21. "Organic Speciation International Workshop Synthesis_topic7". Retrieved 19 February 2010.
  22. Krevelen, D.W. van; Nijenhuis, Klaas te (2009). Properties of Polymers: Their Correlation with Chemical Structure; Their Numerical Estimation and Prediction from Additive Group Contributions. Elsevier. p. 864. ISBN   978-0-08-054819-7.
  23. Pope, C. Arden; Burnett, Richard T.; Turner, Michelle C.; Cohen, Aaron; Krewski, Daniel; Jerrett, Michael; Gapstur, Susan M.; Thun, Michael J. (November 2011). "Lung Cancer and Cardiovascular Disease Mortality Associated with Ambient Air Pollution and Cigarette Smoke: Shape of the Exposure–Response Relationships". Environmental Health Perspectives. 119 (11): 1616–1621. doi:10.1289/ehp.1103639. PMC   3226505 . PMID   21768054.
  24. St Cyr, MD, Richard (16 January 2013). "Is PM2.5 From Air Pollution The Same As From Smoking?". My Health Beijing. Retrieved 16 September 2015.
  25. Cupitt, L T; Glen, W G; Lewtas, J (October 1994). "Exposure and risk from ambient particle-bound pollution in an airshed dominated by residential wood combustion and mobile sources". Environmental Health Perspectives. 102 (suppl 4): 75–84. doi:10.1289/ehp.94102s475. PMC   1566933 . PMID   7529707.
  26. General, Surgeon. "The Health Consequences of Involuntary Exposure to Tobacco Smoke: A Report of the Surgeon General" (PDF). U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health. Retrieved 27 February 2017.
  27. "Secondhand Smoke". American Cancer Society. Retrieved 11 January 2011.
  28. " – Warehouse Tragedy".
  29. Ronald C. Lasky, Ronald Lasky, Ulf L. Österberg, Daniel P. Stigliani (1995). Optoelectronics for data communication. Academic Press. p. 43. ISBN   978-0-12-437160-6.{{cite book}}: CS1 maint: uses authors parameter (link)
  30. EPA, NSW. "reducing-wood-smoke-emissions". NSW Environment Protection Authority.
  31. 1 2 3 "Department of Agriculture, Water and the Environment". Department of Agriculture, Water and the Environment.
  32. "Wood smoke major source of pollution in winter" (PDF). 2007. Retrieved 2 May 2021.
  33. "Air pollution and health" (PDF). Retrieved 2 May 2021.
  34. 1 2 Tsiodra, Irini; Grivas, Georgios; Tavernaraki, Kalliopi; Bougiatioti, Aikaterini; Apostolaki, Maria; Paraskevopoulou, Despina; Gogou, Alexandra; Parinos, Constantine; Oikonomou, Konstantina; Tsagkaraki, Maria; Zarmpas, Pavlos; Nenes, Athanasios; Mihalopoulos, Nikolaos (7 December 2021). "Annual exposure to polycyclic aromatic hydrocarbons in urban environments linked to wintertime wood-burning episodes". Atmospheric Chemistry and Physics. 21 (23): 17865–17883. Bibcode:2021ACP....2117865T. doi: 10.5194/acp-21-17865-2021 . ISSN   1680-7316. S2CID   245103794.
  35. US EPA, OAR (28 May 2013). "Wood Smoke and Your Health". US EPA.
  36. Hawkes, N. (22 May 2015). "Air pollution in UK: the public health problem that won't go away". BMJ. 350 (may22 1): h2757. doi:10.1136/bmj.h2757. PMID   26001592. S2CID   40717317.
  37. Carrington, Damian (16 February 2021). "Wood burning at home now biggest cause of UK particle pollution". The Guardian. Retrieved 13 February 2022.
  38. 1 2 "Wood burning heaters and your health - Fact sheets".
  39. "Wood smoke and your health". Minnesota Pollution Control Agency. 16 November 2009.
  40. "Wood stove pollution is a burning issue".
  41. Danielsen, Pernille Høgh; Møller, Peter; Jensen, Keld Alstrup; Sharma, Anoop Kumar; Wallin, Håkan; Bossi, Rossana; Autrup, Herman; Mølhave, Lars; Ravanat, Jean-Luc; Briedé, Jacob Jan; de Kok, Theo Martinus; Loft, Steffen (18 February 2011). "Oxidative Stress, DNA Damage, and Inflammation Induced by Ambient Air and Wood Smoke Particulate Matter in Human A549 and THP-1 Cell Lines". Chemical Research in Toxicology. 24 (2): 168–184. doi:10.1021/tx100407m. PMID   21235221. S2CID   11668269.
  42. Navarro, Kathleen M.; Kleinman, Michael T.; Mackay, Chris E.; Reinhardt, Timothy E.; Balmes, John R.; Broyles, George A.; Ottmar, Roger D.; Naher, Luke P.; Domitrovich, Joseph W. (June 2019). "Wildland firefighter smoke exposure and risk of lung cancer and cardiovascular disease mortality". Environmental Research. 173: 462–468. Bibcode:2019ER....173..462N. doi:10.1016/j.envres.2019.03.060. PMID   30981117. S2CID   108987257.
  43. "Don't underestimate the health dangers of wood smoke".
  44. Bede-Ojimadu, Onyinyechi; Orisakwe, Orish Ebere (20 March 2020). "Exposure to Wood Smoke and Associated Health Effects in Sub-Saharan Africa: A Systematic Review". Annals of Global Health. 86 (1): 32. doi: 10.5334/aogh.2725 . PMC   7082829 . PMID   32211302.
  45. Peeples, Lynne (23 June 2020). "News Feature: How air pollution threatens brain health". Proceedings of the National Academy of Sciences. 117 (25): 13856–13860. Bibcode:2020PNAS..11713856P. doi: 10.1073/pnas.2008940117 . PMC   7322062 . PMID   32493753.
  46. "Air pollution particles in young brains linked to Alzheimer's damage". the Guardian. 6 October 2020.
  47. "Air Pollution May Damage People's Brains". The Scientist Magazine®.
  48. "Stanford study shows wood smoke can harm the brain". ABC7 San Francisco. 2 December 2017.
  49. Flores-Pajot, Marie-Claire; Ofner, Marianna; Do, Minh T.; Lavigne, Eric; Villeneuve, Paul J. (November 2016). "Childhood autism spectrum disorders and exposure to nitrogen dioxide, and particulate matter air pollution: A review and meta-analysis". Environmental Research. 151: 763–776. Bibcode:2016ER....151..763F. doi:10.1016/j.envres.2016.07.030. PMID   27609410.
  50. Chun, HeeKyoung; Leung, Cheryl; Wen, Shi Wu; McDonald, Judy; Shin, Hwashin H. (January 2020). "Maternal exposure to air pollution and risk of autism in children: A systematic review and meta-analysis". Environmental Pollution. 256: 113307. doi: 10.1016/j.envpol.2019.113307 . PMID   31733973.
  51. Lam, Juleen; Sutton, Patrice; Kalkbrenner, Amy; Windham, Gayle; Halladay, Alycia; Koustas, Erica; Lawler, Cindy; Davidson, Lisette; Daniels, Natalyn; Newschaffer, Craig; Woodruff, Tracey (21 September 2016). "A Systematic Review and Meta-Analysis of Multiple Airborne Pollutants and Autism Spectrum Disorder". PLOS ONE. 11 (9): e0161851. Bibcode:2016PLoSO..1161851L. doi: 10.1371/journal.pone.0161851 . PMC   5031428 . PMID   27653281.
  52. Weisskopf, Marc G.; Kioumourtzoglou, Marianthi-Anna; Roberts, Andrea L. (December 2015). "Air Pollution and Autism Spectrum Disorders: Causal or Confounded?". Current Environmental Health Reports. 2 (4): 430–439. doi:10.1007/s40572-015-0073-9. PMC   4737505 . PMID   26399256.
  53. Fu, Pengfei; Yung, Ken Kin Lam (15 September 2020). "Air Pollution and Alzheimer's Disease: A Systematic Review and Meta-Analysis". Journal of Alzheimer's Disease. 77 (2): 701–714. doi:10.3233/JAD-200483. PMID   32741830. S2CID   220942039.
  54. Tsai, Tsung-Lin; Lin, Yu-Ting; Hwang, Bing-Fang; Nakayama, Shoji F.; Tsai, Chon-Haw; Sun, Xian-Liang; Ma, Chaochen; Jung, Chau-Ren (October 2019). "Fine particulate matter is a potential determinant of Alzheimer's disease: A systemic review and meta-analysis". Environmental Research. 177: 108638. Bibcode:2019ER....177j8638T. doi:10.1016/j.envres.2019.108638. PMID   31421449. S2CID   201057595.
  55. 1 2 Braithwaite, Isobel; Zhang, Shuo; Kirkbride, James B.; Osborn, David P. J.; Hayes, Joseph F. (December 2019). "Air Pollution (Particulate Matter) Exposure and Associations with Depression, Anxiety, Bipolar, Psychosis and Suicide Risk: A Systematic Review and Meta-Analysis". Environmental Health Perspectives. 127 (12): 126002. doi:10.1289/EHP4595. PMC   6957283 . PMID   31850801.
  56. 1 2 Lu, Jackson G (April 2020). "Air pollution: A systematic review of its psychological, economic, and social effects". Current Opinion in Psychology. 32: 52–65. doi:10.1016/j.copsyc.2019.06.024. PMID   31557706. S2CID   199147061.
  57. 1 2 Liu, Qisijing; Wang, Wanzhou; Gu, Xuelin; Deng, Furong; Wang, Xueqin; Lin, Hualiang; Guo, Xinbiao; Wu, Shaowei (February 2021). "Association between particulate matter air pollution and risk of depression and suicide: a systematic review and meta-analysis". Environmental Science and Pollution Research. 28 (8): 9029–9049. doi:10.1007/s11356-021-12357-3. PMID   33481201. S2CID   231677095.
  58. Fan, Shu-Jun; Heinrich, Joachim; Bloom, Michael S.; Zhao, Tian-Yu; Shi, Tong-Xing; Feng, Wen-Ru; Sun, Yi; Shen, Ji-Chuan; Yang, Zhi-Cong; Yang, Bo-Yi; Dong, Guang-Hui (January 2020). "Ambient air pollution and depression: A systematic review with meta-analysis up to 2019". Science of the Total Environment. 701: 134721. Bibcode:2020ScTEn.701m4721F. doi:10.1016/j.scitotenv.2019.134721. PMID   31715478. S2CID   207944384.
  59. Maher, Barbara A.; Ahmed, Imad A. M.; Karloukovski, Vassil; MacLaren, Donald A.; Foulds, Penelope G.; Allsop, David; Mann, David M. A.; Torres-Jardón, Ricardo; Calderon-Garciduenas, Lilian (27 September 2016). "Magnetite pollution nanoparticles in the human brain". Proceedings of the National Academy of Sciences. 113 (39): 10797–10801. Bibcode:2016PNAS..11310797M. doi: 10.1073/pnas.1605941113 . PMC   5047173 . PMID   27601646.
  60. Sorensen, Roy (2016). A Cabinet of Philosophical Curiosities: A Collection of Puzzles, Oddities, Riddles, and Dilemmas. Oxford University Press. p. 89. ISBN   978-0190468637.
  61. Watson, Donna S. (8 March 2010). Perioperative Safety. Amsterdam, Netherlands: Elsevier Health Sciences. ISBN   978-0-323-06985-4.
  62. National Academies (1 January 1983). Polycyclic Aromatic Hydrocarbons: Evaluation of Sources and Effects (Report). National Academies. p. 4.
  63. Harrison & others, Roy M (26 August 2013). "An evaluation of some issues regarding the use of aethalometers to measure woodsmoke concentrations" (PDF). Atmospheric Environment. 80: 540–548. Bibcode:2013AtmEn..80..540H. doi:10.1016/j.atmosenv.2013.08.026.
  64. Mohagheghzadeh, Abdolali; Faridi, Pouya; Shams-Ardakani, Mohammadreza; Ghasemi, Younes (2006). "Medicinal smokes". Journal of Ethnopharmacology. 108 (2): 161–84. doi:10.1016/j.jep.2006.09.005. PMID   17030480.

Sources 7 things you need to know about smoke detectors]