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71-406: Diesel exhaust fluid ( DEF ; also known as AUS 32 and sometimes marketed as AdBlue ) is a liquid used to reduce the amount of air pollution created by a diesel engine. Specifically, DEF is an aqueous urea solution made with 32.5% urea and 67.5% deionized water . DEF is consumed in a selective catalytic reduction (SCR) that lowers the concentration of nitrogen oxides ( NO x ) in

142-501: A compilation of air pollutant emission factors for a wide range of industrial sources. The United Kingdom, Australia, Canada, and many other countries have published similar compilations, as well as the European Environment Agency . An air pollutant is a material in the air that can have many effects on humans and the ecosystem. The substance can be solid particles, liquid droplets, or gases, and often takes

213-768: A faster rate of breathing than a child engaged in sedentary activity. The daily exposure must therefore include the amount of time spent in each micro-environmental setting as well as the kind of activities performed there. The air pollutant concentration in each microactivity/microenvironmental setting is summed to indicate the exposure. For some pollutants such as black carbon , traffic related exposures may dominate total exposure despite short exposure times since high concentrations coincide with proximity to major roads or participation in (motorized) traffic. A large portion of total daily exposure occurs as short peaks of high concentrations, but it remains unclear how to define peaks and determine their frequency and health impact. In 2021,

284-657: A health environment is not maintained. Even at levels lower than those considered safe by United States regulators, exposure to three components of air pollution, fine particulate matter, nitrogen dioxide and ozone, correlates with cardiac and respiratory illness. Individual reactions to air pollutants depend on the type of pollutant a person is exposed to, the degree of exposure, and the individual's health status and genetics. The most common sources of air pollution include particulates and ozone (often from burning fossil fuels), nitrogen dioxide, and sulfur dioxide. Children aged less than five years who live in developing countries are

355-465: A large amount of DEF. As of 2013, many truck stops have added DEF pumps. These are usually adjacent to fuel pumps so the driver can fill both tanks without moving the truck. In Europe, increasing numbers of fuel stations offer dispensers that pump Diesel Exhaust Fluid rather than the traditional method of using disposable, single-use plastic containers. These pumped dispensers are often targeted at commercial vehicles but are now also starting to emerge as

426-562: A legal definition of air pollution, 31 percent lack outdoor air quality standards, 49 percent restrict their definition to outdoor pollution only, and just 31 percent have laws for tackling pollution originating from outside their borders. National air quality laws have often been highly effective, notably the 1956 Clean Air Act in Britain and the US Clean Air Act , introduced in 1963. Some of these efforts have been successful at

497-482: A link between air pollution levels and longevity. The WHO estimates that in 2016, ~58% of outdoor air pollution-related premature deaths were due to ischaemic heart disease and stroke. The mechanisms linking air pollution to increased cardiovascular mortality are uncertain, but probably include pulmonary and systemic inflammation. India and China have the highest death rate due to air pollution. India also has more deaths from asthma than any other nation according to

568-415: A mixture of natural and human sources. There are also sources from processes other than combustion : Air pollutant emission factors are reported representative values that aim to link the quantity of a pollutant released into the ambient air to an activity connected with that pollutant's release. The weight of the pollutant divided by a unit weight, volume, distance, or time of the activity generating

639-411: A move that now impacts 40% of registered vehicles. Diesel vehicles made since 2015 were required to be fitted with SCR systems. The South Korean government started rationing urea solution, and banned its resale as panic buying by drivers exacerbated an acute shortage that could cause transport and industry to grind to a halt. A KC-330 Cygnus was sent to import Diesel exhaust fluid from Australia to ease

710-422: A new plant. Air pollution Air pollution is the contamination of air due to the presence of substances called pollutants in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. It is also the contamination of the indoor or outdoor environment either by chemical, physical, or biological agents that alters the natural features of

781-524: A number of bases in carbon tetrachloride solution at 25 °C have been reported. The acceptor properties of HNCO are compared with other Lewis acid in the ECW model . Low-temperature photolysis of solids containing HNCO creates the tautomer cyanic acid H−O−C≡N , also called hydrogen cyanate. Pure cyanic acid has not been isolated, and isocyanic acid is the predominant form in all solvents. Sometimes information presented for cyanic acid in reference books

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852-534: A shortage of DEF in South Korea was continuing and brought havoc to its economy. As most of the urea used is supplied by China, imports have slowed since China introduced mandatory inspections of urea exports in September. Nearly 97% of South Korea's urea imports came from China between January and September. In 2015, South Korea had made it mandatory for diesel cars to use urea solutions to control emissions,

923-439: A solution for the growing number of passenger cars that require DEF by volume. At airports, where DEF can sometimes be required for diesel ground service vehicles, its labelling and storage must be carefully managed to avoid accidentally servicing jet aircraft with DEF instead of fuel system icing inhibitor , a mistake that has been blamed for multiple in-flight engine failure and grounding incidents. As of December 2021,

994-426: A spectrum of clinical disorders that include emphysema , bronchiectasis , and chronic bronchitis . COPD risk factors are both genetic and environmental. Elevated particle pollution contributes to the exacerbation of this disease and likely its pathogenesis. The risk of lung disease from air pollution is greatest for infants and young children, whose normal breathing is faster than that of older children and adults;

1065-475: A sufficient amount of the frozen DEF must be melted in as short time as possible, preferably on the order of minutes. For example, 2010 EPA emissions requirements require full DEF coolant flow within 70 minutes. In Europe, Regulation (EC) No 692/2008 specified in Annex XVI point 10 that DEF from a frozen tank at a core temperature of −15 °C (5 °F) must become available within 20 minutes when starting

1136-683: A supply shortage of the key material used in diesel vehicles. In early December 2021, the Australian National Road Transport Association also raised concerns about a shortage of DEF in the country due to the shortage of urea in China. China capped exports to protect its domestic supplies and rising DEF prices. By mid-December, there was approximately 7 weeks' supply of AdBlue left in Australia. On 14 December, Australian company IOR stated that it would build

1207-566: A total of 460,000 deaths in the US were attributed to coal PM 2.5 . The largest cause of air pollution is fossil fuel combustion  – mostly the production and use of cars , electricity production, and heating. There are estimated 4.5 million annual premature deaths worldwide due to pollutants released by high-emission power stations and vehicle exhausts. Diesel exhaust (DE) is a major contributor to combustion-derived particulate matter air pollution. In several human experimental studies, using

1278-794: A well-validated exposure chamber setup, DE has been linked to acute vascular dysfunction and increased thrombus formation. A study concluded that PM 2.5 air pollution induced by the contemporary free trade and consumption by the 19 G20 nations causes two million premature deaths annually, suggesting that the average lifetime consumption of about ~28 people in these countries causes at least one premature death (average age ~67) while developing countries "cannot be expected" to implement or be able to implement countermeasures without external support or internationally coordinated efforts. The US EPA has estimated that limiting ground-level ozone concentration to 65 parts per billion (ppb), would avert 1,700 to 5,100 premature deaths nationwide in 2020 compared with

1349-494: A year and fine particulate (PM 2.5 ) pollution around another 2.1 million. The scope of the air pollution crisis is large: In 2018, WHO estimated that "9 out of 10 people breathe air containing high levels of pollutants." Although the health consequences are extensive, the way the problem is handled is considered largely haphazard or neglected. The World Bank has estimated that welfare losses (premature deaths) and productivity losses (lost labour) caused by air pollution cost

1420-510: Is a significant risk factor for a number of pollution-related diseases , including respiratory infections , heart disease , chronic obstructive pulmonary disease (COPD), stroke , and lung cancer . Growing evidence suggests that air pollution exposure may be associated with reduced IQ scores, impaired cognition, increased risk for psychiatric disorders such as depression and detrimental perinatal health. The human health effects of poor air quality are far reaching, but principally affect

1491-408: Is actually for isocyanic acid. Isocyanic acid can be made by protonation of the cyanate anion , such as from salts like potassium cyanate , by either gaseous hydrogen chloride or acids such as oxalic acid . HNCO also can be made by the high-temperature thermal decomposition of the trimer cyanuric acid : In the reverse of the famous synthesis of urea by Friedrich Wöhler , isocyanic acid

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1562-851: Is associated with nearly one in three strokes (29%) worldwide (33.7% of strokes in developing countries versus 10.2% in developed countries). In women, air pollution is not associated with hemorrhagic but with ischemic stroke. Air pollution was found to be associated with increased incidence and mortality from coronary stroke. Associations are believed to be causal and effects may be mediated by vasoconstriction, low-grade inflammation and atherosclerosis . Other mechanisms such as autonomic nervous system imbalance have also been suggested. Research has demonstrated increased risk of developing asthma and chronic obstructive pulmonary disease (COPD) from increased exposure to traffic-related air pollution. Air pollution has been associated with increased hospitalization and mortality from asthma and COPD. COPD comprises

1633-438: Is clear, non-toxic and safe to handle. Since urea has corrosive impact on metals like aluminium, DEF is stored and transported in special containers. These containers are typically made of stainless steel. Vehicles' selective catalytic reduction (SCR) systems and DEF dispensers are designed in a manner that there is no corrosive impact of urea on them. It is recommended that DEF be stored in a cool, dry, and well-ventilated area that

1704-459: Is introduced with the use of air fresheners , incense , and other scented items. Controlled wood fires in cook stoves and fireplaces can add significant amounts of harmful smoke particulates into the air, inside and out. Indoor pollution fatalities may be caused by using pesticides and other chemical sprays indoors without proper ventilation. Also the kitchen in a modern produce harmful particles and gases, with equipment like toasters being one of

1775-401: Is made and distributed for retail sale by Prime Lubes, Inc. Diesel engines are typically operated with a lean burn air-to-fuel ratio ( over-stoichiometric ratio) to ensure the full combustion of soot and to prevent them from exhausting unburnt fuel. The excess air leads to the generation of NO x , which are harmful pollutants , from nitrogen in the atmosphere. SCR is used to reduce

1846-470: Is more NO than NO 2 , fast SCR and standard SCR take place sequentially. If there is more NO 2 than NO , fast SCR and NO 2 SCR take place sequentially, however, NO 2 SCR is slower than standard SCR, and ammonium nitrate can form and temporarily deactivate the catalytic converter. DEF freezes at −11 °C (12 °F). For the SCR exhaust cleaning system to function at low temperatures,

1917-673: Is nitrogen dioxide and other nitrogen oxides (NOx) emitted by road vehicles. Across the European Union , air pollution is estimated to reduce life expectancy by almost nine months. In a 2015 consultation document the UK government disclosed that nitrogen dioxide is responsible for 23,500 premature UK deaths per annum. There is a positive correlation between pneumonia -related deaths and air pollution from motor vehicle emissions in England. Eliminating energy-related fossil fuel emissions in

1988-425: Is out of direct sunlight. Bulk volumes of DEF are compatible for storage within polyethylene containers ( HDPE , XLPE ), fiberglass reinforced plastic ( FRP ), and steel tanks. DEF is also often handled in intermediate bulk containers for storage and shipping. DEF is offered to consumers in a variety of quantities ranging from containers for single or repeated small usage, up to bulk carriers for consumers requiring

2059-408: Is strong evidence linking both short- and long-term exposure to air pollution with cardiovascular disease mortality and morbidity, stroke, blood pressure, and ischemic heart diseases (IHD). Air pollution is a leading risk factor for stroke, particularly in developing countries where pollutant levels are highest. A systematic analysis of 17 different risk factors in 188 countries found air pollution

2130-665: The diesel exhaust emissions from a diesel engine . In the international standard defining DEF ( ISO 22241), it is referred to as AUS 32 (aqueous urea solution 32%). DEF is also sold as AdBlue, a registered trademark of the German Association of the Automotive Industry . Several brands of SCR systems use DEF: BlueHDI is used by PSA Group vehicles including Peugeot , Citroën , and DS Automobiles brands; BlueTec by Daimler AG ; and FLENDS (Final Low Emission New Diesel System) by UD Trucks . Blue Sky DEF

2201-490: The trimer cyanuric acid and cyamelide , a polymer. These species usually are easily separated from liquid- or gas-phase reaction products. Isocyanic acid reacts with amines to give ureas (carbamides): This reaction is called carbamylation . HNCO adds across electron-rich double bonds, such as vinylethers , to give the corresponding isocyanates. Isocyanic acid, HNCO, is a Lewis acid whose free energy , enthalpy and entropy changes for its 1:1 association with

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2272-454: The world economy $ 5 trillion per year. The costs of air pollution are generally an externality to the contemporary economic system and most human activity, although they are sometimes recovered through monitoring, legislation, and regulation . Many different technologies and strategies are available for reducing air pollution. Although a majority of countries have air pollution laws , according to UNEP , 43 percent of countries lack

2343-570: The 2268.8 cm is the asymmetric N=C=O stretch, as per Colthup et al., as well as the NIST Chemistry WebBook, which also reports the corresponding symmetric N=C=O stretch (weak in infrared, but strong in Raman) to be 1327 cm . Based on these classic assignments, there is no need to invoke a full charged state for the N and O atoms, to explain the vibrational spectral data. The tautomer , known as cyanic acid, HOCN, in which

2414-544: The 75 ppb standard. The agency projected the more protective standard would also prevent an additional 26,000 cases of aggravated asthma, and more than a million cases of missed work or school. Following this assessment, the EPA acted to protect public health by lowering the National Ambient Air Quality Standards (NAAQS) for ground-level ozone to 70 ppb. A 2008 economic study of

2485-989: The American Lung Association; the US Consumer Product Safety Commission (CPSC) 2012; and the US Environmental Protection Agency 2012a. Indoor contaminants that can cause pollution include asbestos, biologic agents, building materials, radon, tobacco smoke, and wood stoves, gas ranges, or other heating systems. Radon (Rn) gas, a carcinogen , is exuded from the Earth in certain locations and trapped inside houses. Building materials including carpeting and plywood emit formaldehyde (H-CHO) gas. Paint and solvents give off volatile organic compounds (VOCs) as they dry. Lead paint can degenerate into dust and be inhaled. Intentional air pollution

2556-590: The DEF tank. This heater must be sized, positioned, and powered adequately to rapidly melt sufficient frozen DEF. It should preferably be self regulating not to overheat if (part of) the heater is outside of the liquid. It should also preferably be self regulating to eliminate any complicated sensor and temperature regulating systems. Furthermore, the heater should not exceed 50–60 °C (122–140 °F), as DEF begins to decompose at around 60 °C (140 °F). PTC heaters are often used to achieve this. The urea solution

2627-631: The USA under the Clean Air Act and in Europe under numerous directives (including the Air "Framework" Directive, 96/62/EC, on ambient air quality assessment and management, Directive 98/24/EC, on risks related to chemical agents at work, and Directive 2004/107/EC covering heavy metals and polycyclic aromatic hydrocarbons in ambient air). The risk of air pollution is determined by the pollutant's hazard and

2698-567: The United States would prevent 46,900–59,400 premature deaths each year and provide $ 537–$ 678 billion in benefits from avoided PM 2.5 -related illness and death. A study published in 2023 in Science focused on sulfur dioxide emissions by coal power plants (coal PM 2.5 ) and concluded that "exposure to coal PM 2.5 was associated with 2.1 times greater mortality risk than exposure to PM 2.5 from all sources." From 1999 to 2020,

2769-463: The WHO halved its recommended guideline limit for tiny particles from burning fossil fuels. The new limit for nitrogen dioxide (NO 2 ) is 75% lower. Growing evidence that air pollution—even when experienced at very low levels—hurts human health, led the WHO to revise its guideline (from 10 μg/m to 5 μg/m ) for what it considers a safe level of exposure of particulate pollution, bringing most of

2840-402: The WHO reported that outdoor air pollution was estimated to cause 4.2 million premature deaths worldwide in 2019. The global mean loss of life expectancy (LLE; similar to YPLL ) from air pollution in 2015 was 2.9 years, substantially more than, for example, 0.3 years from all forms of direct violence. Communities with persons that live beyond 85 years have low ambient air pollution, suggesting

2911-754: The World Health Organization estimated that every year air pollution causes the premature death of 7 million people worldwide, 1 in 8 deaths worldwide. A study published in 2019 indicated that in 2015 the number may be closer to 8.8 million, with 5.5 million of these premature deaths due to air pollution from anthropogenic sources. A 2022 review concluded that in 2019 air pollution was responsible for approximately 9 million premature deaths. It concluded that since 2015 little real progress against pollution has been made. Causes of deaths include strokes, heart disease, COPD , lung cancer, and lung infections. Children are particularly at risk. In 2021,

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2982-778: The World Health Organization, these may be defined as asbestosis, lung cancer, and peritoneal mesothelioma (generally a very rare form of cancer, when more widespread it is almost always associated with prolonged exposure to asbestos). Biological sources of air pollution are also found indoors, as gases and airborne particulates. Pets produce dander, people produce dust from minute skin flakes and decomposed hair, dust mites in bedding, carpeting and furniture produce enzymes and micrometre-sized fecal droppings, inhabitants emit methane, mold forms on walls and generates mycotoxins and spores, air conditioning systems can incubate Legionnaires' disease and mold, and houseplants, soil and surrounding gardens can produce pollen , dust, and mold. Indoors,

3053-519: The World Health Organization. In 2019, 1.6 million deaths in India were caused by air pollution. In 2013, air pollution was estimated to kill 500,000 people in China each year. In 2012, 2.48% of China's total air pollution emissions were caused by exports due to US demand, causing an additional 27,963 deaths across 30 provinces. Annual premature European deaths caused by air pollution are estimated at 430,000 to 800,000. An important cause of these deaths

3124-415: The addition of fluid in accordance with parameters such as NO x level in the exhaust gas (before catalytic converter, after catalytic converter, and possibly between catalytic converters if there is more than one), current ammonia filling level, engine operating temperature and speed. DEF is a 32.5% solution of urea, (NH 2 ) 2 CO . When it is injected into the hot exhaust gas stream,

3195-445: The air when primary pollutants react or interact. Ground level ozone is a prominent example of a secondary pollutant. Some pollutants may be both primary and secondary: they are both emitted directly and formed from other primary pollutants. Pollutants emitted into the atmosphere by human activity include: Secondary pollutants include: There are many other chemicals classed as hazardous air pollutants. Some of these are regulated in

3266-502: The amount of NO x released into the atmosphere. DEF from a separate tank is injected into the exhaust pipeline, and the exhaust heat decomposes it to ammonia. Within the SCR catalyst , the NO x are reduced by the ammonia into water and nitrogen , which are both nonpolluting. The water and nitrogen are then released into the atmosphere through the exhaust. SCR was applied to automobiles by Nissan Diesel Corporation , and

3337-704: The amount of exposure to that pollutant. Air pollution exposure can be measured for a person, a group, such as a neighborhood or a country's children, or an entire population. For example, one would want to determine a geographic area's exposure to a dangerous air pollution, taking into account the various microenvironments and age groups. This can be calculated as an inhalation exposure. This would account for daily exposure in various settings, e.g. different indoor micro-environments and outdoor locations. The exposure needs to include different ages and other demographic groups, especially infants, children, pregnant women, and other sensitive subpopulations. For each specific time that

3408-429: The atmosphere. There are many different types of air pollutants, such as gases (including ammonia , carbon monoxide , sulfur dioxide , nitrous oxides , methane and chlorofluorocarbons ), particulates (both organic and inorganic) and biological molecules . Air pollution can cause diseases, allergies, and even death to humans; it can also cause harm to other living organisms such as animals and crops, and may damage

3479-411: The body's respiratory system and the cardiovascular system . Individual reactions to air pollutants depend on the type of pollutant a person is exposed to, the degree of exposure, and the individual's health status and genetics . Air pollution is the largest environmental risk factor for disease and premature death and the fourth largest risk factor overall for human health. Air pollution causes

3550-487: The elderly; those who work outside or spend a lot of time outside; and those who have heart or lung disease comorbidities . Isocyanic acid The derived anion of isocyanic acid is the same as the derived anion of cyanic acid, and that anion is [N=C=O] , which is called cyanate . The related functional group −N=C=O is isocyanate ; it is distinct from cyanate ( −O−C≡N ), fulminate ( −O−N ≡C ), and nitrile oxide ( −C≡N −O ). Isocyanic acid

3621-456: The elusive fulminic acid ( H−C≡N −O ) and isofulminic acid H−O−N ≡C . Although the electronic structure according to valence bond theory can be written as H−N=C=O, the vibrational spectrum has a band at 2268.8 cm in the gas phase, which some say indicates a carbon–nitrogen triple bond. If so, then the canonical form H−N ≡C−O is the major resonance structure . However, classic vibrational analysis would indicate that

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3692-432: The engine at −15 °C (5 °F). Typically, the frozen DEF is melted by heat from the engine, e.g. engine coolant passing through the DEF tank, governed by a thermostatic coolant control valve. This method may take significant time before the SCR exhaust cleaning system is fully operational, often up to an hour. Another method to thaw DEF (and thus allow for full SCR operation) is to integrate an electric heater into

3763-663: The extensive use of asbestos in industrial and domestic environments in the past has left a potentially very dangerous material in many localities. Asbestosis is a chronic inflammatory medical condition affecting the tissue of the lungs. It occurs after long-term, heavy exposure to asbestos from asbestos-containing materials in structures. Those with asbestosis have severe dyspnea (shortness of breath) and are at an increased risk regarding several different types of lung cancer . As clear explanations are not always stressed in non-technical literature, care should be taken to distinguish between several forms of relevant diseases. According to

3834-635: The first practical product " Nissan Diesel Quon " was introduced in 2004. With the cooperation of the oil and chemical industry, a 1,300-station infrastructure to supply DEF was prepared by September 2005 in Japan. In 2007, the United States Environmental Protection Agency (EPA) enacted requirements to significantly reduce harmful exhaust emissions. To achieve this standard, Cummins and other diesel engine manufacturers developed an aftertreatment system that includes

3905-470: The form of an aerosol (solid particles or liquid droplets dispersed and carried by a gas). A pollutant can be of natural origin or man-made. Pollutants are classified as primary or secondary. Primary pollutants are usually produced by processes such as ash from a volcanic eruption. Other examples include carbon monoxide gas from motor vehicle exhausts or sulfur dioxide released from factories. Secondary pollutants are not emitted directly. Rather, they form in

3976-520: The health impacts and associated costs of air pollution in the Los Angeles Basin and San Joaquin Valley of Southern California shows that more than 3,800 people die prematurely (approximately 14 years earlier than normal) each year because air pollution levels violate federal standards. The number of annual premature deaths is considerably higher than the fatalities related to auto collisions in

4047-638: The international level, such as the Montreal Protocol , which reduced the release of harmful ozone depleting chemicals, and the 1985 Helsinki Protocol , which reduced sulfur emissions , while others, such as international action on climate change , have been less successful. There are many different sources of air pollution. Some air pollutants (such as nitrogen oxides) originate mainly from human activities, while some (notably radon gas) come mostly from natural sources. However, many air pollutants (including dust and sulfur dioxide) come from

4118-1014: The lack of air circulation allows these airborne pollutants to accumulate more than they would otherwise occur in nature. Air pollution has both acute and chronic effects on human health, affecting a number of different systems and organs but principally affect the body's respiratory system and the cardiovascular system. Afflictions include minor to chronic upper respiratory irritation such as difficulty in breathing, wheezing, coughing, asthma and heart disease , lung cancer , stroke , acute respiratory infections in children and chronic bronchitis in adults, aggravating pre-existing heart and lung disease, or asthmatic attacks. Short and long term exposures have been linked with premature mortality and reduced life expectancy and can result in increased medication use, increased doctor or emergency department visits, more hospital admissions and premature death. Diseases that develop from persistent exposure to air pollution are environmental health diseases, which develop when

4189-495: The more stringent 2010 EPA regulations, which reduced NO x levels even further. In 2008, the concerns about compliance shifted to the infrastructure for DEF distribution. The injection rate of DEF into the exhaust depends on the specific after-treatment system, but is typically 2–6% of diesel consumption volume. This low dosing rate ensures long fluid refill intervals and minimizes the tank's size and intrusion into vehicle packaging space. An electronic control unit adjusts

4260-422: The most vulnerable population to death attributable to indoor and outdoor air pollution. Under the Clean Air Act , U.S. EPA sets limits on certain air pollutants, including setting limits on how much can be in the air anywhere in the United States. Mixed exposure to both carbon black and ozone could result in significantly greater health affects. Estimates of deaths toll due to air pollution vary. In 2014

4331-498: The natural environment (for example, climate change , ozone depletion or habitat degradation ) or built environment (for example, acid rain ). Air pollution can be caused by both human activities and natural phenomena. Air quality is closely related to the Earth's climate and ecosystems globally. Many of the contributors of air pollution are also sources of greenhouse emission i.e., burning of fossil fuel . Air pollution

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4402-529: The oxygen atom is protonated exists in equilibrium with isocyanic acid to the extent of about 3%. The vibrational spectrum is indicative of the presence of a triple bond between the nitrogen and carbon atoms. In aqueous solution it is a weak acid , having a p K a of 3.7: Isocyanic acid hydrolyses to carbon dioxide and ammonia : Dilute solutions of isocyanic acid are stable in inert solvents , e.g. ether and chlorinated hydrocarbons . At high concentrations, isocyanic acid oligomerizes to give

4473-742: The pollutant is how these factors are commonly stated (e.g., kilograms of particulate emitted per tonne of coal burned). These criteria make estimating emissions from diverse sources of pollution easier. Most of the time, these components are just averages of all available data of acceptable quality, and they are thought to be typical of long-term averages. The Stockholm Convention on Persistent Organic Pollutants identified pesticides and other persistent organic pollutants of concern. These include dioxins and furans which are unintentionally created by combustion of organics, like open burning of plastics, and are endocrine disruptors and mutagens . The United States Environmental Protection Agency has published

4544-468: The premature deaths of around 7 million people worldwide each year, or a global mean loss of life expectancy (LLE) of 2.9 years, and there has been no significant change in the number of deaths caused by all forms of pollution since at least 2015. Outdoor air pollution attributable to fossil fuel use alone causes ~3.61 million deaths annually, making it one of the top contributors to human death . Anthropogenic ozone causes around 470,000 premature deaths

4615-511: The same area, which average fewer than 2,000 per year. A 2021 study found that outdoor air pollution is associated with substantially increased mortality "even at low pollution levels below the current European and North American standards and WHO guideline values" shortly before the WHO adjusted its guidelines. According to the Global Burden of Disease Study , air pollution is responsible for 19% of all cardiovascular deaths. There

4686-462: The subgroup is in the setting and engaged in particular activities, the exposure to an air pollutant must integrate the concentrations of the air pollutant with regard to the time spent in each setting and the respective inhalation rates for each subgroup, playing, cooking, reading, working, spending time in traffic, etc. A little child's inhaling rate, for example, will be lower than that of an adult. A young person engaging in strenuous exercise will have

4757-501: The use of a diesel particulate filter (DPF). As the DPF does not function with low-sulfur diesel fuel, diesel engines that conform to 2007 EPA emissions standards require ultra-low-sulfur diesel (ULSD) fuel to prevent damage to the DPF. After a brief transition period, ULSD fuel became common at fuel pumps in the United States and Canada. The 2007 EPA regulations were meant to be an interim solution to allow manufacturers time to prepare for

4828-651: The water evaporates and the urea thermally decomposes to form ammonia ( NH 3 ) and isocyanic acid (HNCO): The isocyanic acid reacts with the water vapor and hydrolyses to carbon dioxide and ammonia: Overall, thus far: Ammonia, in the presence of oxygen and a catalyst, reduces two different nitrogen oxides: The overall reduction of NO x by urea is then: The ratio between NO 2 and NO determines which reactions take place and how fast. The highest conversion rates are achieved if equal amounts of NO 2 and NO are present, especially at temperatures between 200 °C and 350 °C. If there

4899-525: The world—97.3 percent of the global population—into the unsafe zone. A lack of ventilation indoors concentrates air pollution where people often spend the majority of their time. Indoor air pollution can pose a significant health risk. According to EPA reports, the concentrations of many air pollutants can be two to five times higher in indoor air than in outdoor air. Indoor air pollutants can be up to 100 times higher in some cases than they are inside. People can spend up to 90% of their time indoors, according to

4970-535: The worst sources. Carbon monoxide poisoning and fatalities are often caused by faulty vents and chimneys, or by the burning of charcoal indoors or in a confined space, such as a tent. Chronic carbon monoxide poisoning can result even from poorly-adjusted pilot lights . Traps are built into all domestic plumbing to keep sewer gas and hydrogen sulfide , out of interiors. Clothing emits tetrachloroethylene , or other dry cleaning fluids, for days after dry cleaning. Though its use has now been banned in many countries,

5041-441: Was discovered in 1830 by Justus von Liebig and Friedrich Wöhler . Isocyanic acid is the simplest stable chemical compound that contains carbon , hydrogen , nitrogen , and oxygen , the four most commonly found elements in organic chemistry and biology. It is the only fairly stable one of the four linear isomers with molecular formula HOCN that have been synthesized, the others being cyanic acid (cyanol, H−O−C≡N ) and

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