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Diesel exhaust is the exhaust gas produced by a diesel engine, plus any contained particulates. Its composition may vary with the fuel type, rate of consumption or speed of engine operation (e.g., idling or at speed or under load), and whether the engine is in an on-road vehicle, farm vehicle, locomotive, marine vessel, or stationary generator or other application. [1]
Diesel exhaust causes lung cancer and other diseases such as asthma, and many premature deaths. [2] [3] [4] Methods exist to reduce nitrogen oxides (NOx) and particulate matter (PM) in the exhaust.
Some countries have set a date to stop selling diesel vehicles, and some city centres will ban diesel cars. [5]
The primary products of petroleum fuel combustion in air are carbon dioxide, water, and nitrogen. The other components exist primarily from incomplete combustion and pyro synthesis. [1] [6] While the distribution of the individual components of raw (untreated) diesel exhaust varies depending on factors like load, engine type, etc., the table below shows a typical composition.
The physical and chemical conditions that exist inside any such diesel engines under any conditions differ considerably from spark-ignition engines, because, by design, diesel engine power is directly controlled by the fuel supply, not by control of the air/fuel mixture, as in conventional gasoline engines. [7] As a result of these differences, diesel engines generally produce a different array of pollutants than spark-driven engines, differences that are sometimes qualitative (what pollutants are there, and what are not), but more often quantitative (how much of particular pollutants or pollutant classes are present in each). For instance, diesel engines produce one-twenty-eighth the carbon monoxide that gasoline engines do, as they burn their fuel in excess air even at full load. [8] [9] [10]
However, the lean-burning nature of diesel engines and the high temperatures and pressures of the combustion process result in significant production of NOx (gaseous nitrogen oxides), an air pollutant that constitutes a unique challenge with regard to their reduction.[ not verified in body ] While total nitrogen oxides from petrol cars have decreased by around 96% through the adoption of exhaust catalytic converters as of 2012, diesel cars still produce nitrogen oxides at a similar level to those bought 15 years earlier under real-world tests; hence, diesel cars emit around 20 times more nitrogen oxides than petrol cars. [11] [12] [13] Modern on-road diesel engines typically use selective catalytic reduction (SCR) systems to meet emissions laws, as other methods such as exhaust gas recirculation (EGR) cannot adequately reduce NOx to meet the newer standards applicable in many jurisdictions.
Moreover, the fine particles (fine particulate matter) in diesel exhaust (e.g., soot, sometimes visible as opaque dark-colored smoke) has traditionally been of greater concern, as it presents different health concerns and is rarely produced in significant quantities by spark-ignition engines. These especially harmful particulate contaminants are at their peak when such engines are run without sufficient oxygen to fully combust the fuel; when a diesel engine runs at idle, enough oxygen is usually present to burn the fuel completely. [14] From the particle emission standpoint, exhaust from diesel vehicles has been reported to be significantly more harmful than those from petrol vehicles.
Diesel exhausts, long known for their characteristic smells, changed significantly with the reduction of the sulfur content of diesel fuel, and again when catalytic converters were introduced in exhaust systems.[ not verified in body ] Even so, diesel exhausts continue to contain an array of inorganic and organic pollutants, in various classes, and in varying concentrations (see below), depending on fuel composition and engine running conditions.
Species | Average (Reif 2014) [15] | Average (Merker, Teichmann, 2014) [16] | Diesel's first engine (Hartenstein, 1895) [17] | (Khair, Majewski, 2006) [18] | (various sources) |
---|---|---|---|---|---|
Volume percentage | (Volume?) percentage | ||||
Nitrogen (N2) | 75.2% | 72.1% | - | ~67 % | - |
Oxygen (O2) | 15% | 0.7% | 0.5% | ~9 % | - |
Carbon dioxide (CO2) | 7.1% | 12.3% | 12.5% | ~12 % | - |
Water (H2O) | 2.6% | 13.8% | - | ~11 % | - |
Carbon monoxide (CO) | 0.043% | 0.09% | 0.1% | - | 100–500 ppm [19] |
Nitrogen oxides (NOx) | 0.034% | 0.13% | - | - | 50–1000 ppm [20] |
Hydrocarbons (HC) | 0.005% | 0.09% | - | - | - |
Aldehyde | 0.001% | n/a | - | - | - |
Particulate matter (sulfate + solid substances) | 0.008% | 0.0008% | - | - | 1–30 mg·m−3 [21] |
The following are classes of chemical compounds that have been found in diesel exhaust. [22]
Class of chemical contaminant | Note |
---|---|
Antimony compounds[ citation needed ] | Toxicity similar to arsenic poisoning [23] |
Beryllium compounds | IARC Group 1 carcinogens |
Chromium compounds [24] | IARC Group 3 possible carcinogens |
Cobalt compounds | |
Cyanide compounds [24] | |
Dioxins [24] and dibenzofurans | |
Manganese compounds [24] | |
Mercury compounds [24] | IARC Group 3 possible carcinogens |
Nitrogen oxides [24] | 5.6 ppm or 6500 μg/m³ [1] |
Polycyclic organic matter, including polycyclic aromatic hydrocarbons (PAHs) [1] [24] | |
Selenium compounds | |
Sulfur compounds [24] |
The following are classes of specific chemicals that have been found in diesel exhaust. [24] [ verification needed ][ needs update ] [1] [ page needed ]
§ Includes all regioisomers of this aromatic compound. See ortho-, meta-, and para-isomer descriptions at each compound's article.
This section needs expansionwith: a general introduction with citations that covers current international agreements and federal regulations in English-speaking countries. You can help by adding to it. (October 2015) |
To rapidly reduce particulate matter from heavy-duty diesel engines in California, the California Air Resources Board created the Carl Moyer Memorial Air Quality Standards Attainment Program to provide funding for upgrading engines ahead of emissions regulations. [38] In 2008, the California Air Resources Board also implemented the 2008 California Statewide Truck and Bus Rule which requires all heavy-duty diesel trucks and buses, with a few exceptions, that operate in California to either retrofit or replace engines in order to reduce diesel particulate matter.[ citation needed ]
Unlike international shipping, which had a sulfur limit of 3.5% mass/mass outside ECA until 2020, when it reduced to 0.5% outside ECA, diesel for on road use and off-road (heavy equipment) has been limited throughout the EU since 2009.
Diesel and gasoline have been limited to 10 ppm sulfur since 2009 (for on-road vehicles) and 2011 (non-road vehicles). Mandatory specifications also apply to more than a dozen fuel parameters. [39]
Emissions from diesel vehicles are more harmful than those from petrol vehicles. [40] [41] [42] Diesel combustion exhaust is a source of atmospheric soot and fine particles, which is a component of the air pollution implicated in human cancer, [43] [44] heart and lung damage, [45] and mental functioning. [46] Moreover, diesel exhaust contains contaminants listed as carcinogenic for humans by the IARC (part of the World Health Organization of the United Nations), as present in their List of IARC Group 1 carcinogens. [47] In 2014, diesel exhaust pollution accounted for around one quarter of the pollution in the air and a high share of sickness caused by automotive pollution. [48] [ better source needed ]
Diesel exhaust is a Group 1 carcinogen, which causes lung cancer and has a positive association with bladder cancer. [49] [50] [51] [52] [53] It contains several substances that are also listed individually as human carcinogens by the IARC. [47]
Exposure to diesel exhaust and diesel particulate matter (DPM) is an occupational hazard to truckers, railroad workers, occupants of residential homes in the vicinity of a rail yard, and miners using diesel-powered equipment in underground mines. Adverse health effects have also been observed in the general population at ambient atmospheric particle concentrations well below the concentrations in occupational settings.
In March 2012, U.S. government scientists showed that underground miners exposed to high levels of diesel fumes have a threefold increased risk for contracting lung cancer compared with those exposed to low levels. The $11.5 million Diesel Exhaust in Miners Study (DEMS) followed 12,315 miners, controlling for key carcinogens such as cigarette smoke, radon, and asbestos. This allowed scientists to isolate the effects of diesel fumes. [54] [55]
For over 10 years, concerns have been raised in the US regarding children's exposure to DPM as they ride diesel-powered school buses to and from school. [56] In 2013, the Environmental Protection Agency (EPA) established the Clean School Bus USA initiative in an effort to unite private and public organizations in curbing student exposures. [57]
Diesel particulate matter (DPM), sometimes also called diesel exhaust particles (DEP), is the particulate component of diesel exhaust, which includes diesel soot and aerosols such as ash particulates, metallic abrasion particles, sulfates, and silicates. When released into the atmosphere, DPM can take the form of individual particles or chain aggregates, with most in the invisible sub-micrometer range of 100 nanometers, also known as ultrafine particles (UFP) or PM0.1.
The main particulate fraction of diesel exhaust consists of fine particles. Because of their small size, inhaled particles may easily penetrate deep into the lungs. [1] The polycyclic aromatic hydrocarbons (PAHs) in the exhaust stimulate nerves in the lungs, causing reflex coughing, wheezing and shortness of breath. [58] The rough surfaces of these particles makes it easy for them to bind with other toxins in the environment, thus increasing the hazards of particle inhalation. [14] [ verification needed ] [1]
A study of particulate matter (PM) emissions from transit buses running on ULSD and a mixture of biodiesel and conventional diesel (B20) was reported by Omidvarborna and coworkers, where they concluded that PM emissions appeared lower in cases of mixed diesel/biodiesel use, where they were dependent on the engine model, cold and hot idle modes, and fuel type, and that heavy metals in PM emitted during hot idling were greater than those from cold idling; reasons for PM reduction in biodiesel emissions were suggested to result from the oxygenated structure of biodiesel fuel, as well as arising from changes in technology (including the use of a catalytic converter in this test system). [59] Other studies concluded that while in certain specific cases (i.e. low loads, more saturated feedstocks, ...), NOx emissions can be lower than with diesel fuel, in most cases NOx emissions are higher, and the NOx emissions even go up as more biofuel is mixed in. Pure biodiesel (B100) even ends up having 10-30% more NOx emissions compared to regular diesel fuel. [60]
Exposures have been linked with acute short-term symptoms such as headache, dizziness, light-headedness, nausea, coughing, difficult or labored breathing, tightness of chest, and irritation of the eyes, nose, and throat. [61] Long-term exposures can lead to chronic, more serious health problems such as cardiovascular disease, cardiopulmonary disease, and lung cancer. [43] [44] [62] Elemental carbon attributable to traffic was significantly associated with wheezing at age 1 and persistent wheezing at age 3 in the Cincinnati Childhood Allergy and Air Pollution Study birth cohort study. [63] Ambient traffic-related air pollution is associated with decreased cognitive function in older men. [46]
The study of nanoparticles and nanotoxicology is in its infancy, and health effects from nanoparticles produced by all types of diesel engines are still being uncovered. It is clear, that diesel health detriments of fine particle emissions are severe and pervasive. Although one study found no significant evidence that short-term exposure to diesel exhaust results in adverse extrapulmonary effects, effects that are correlated with an increase in cardiovascular disease, [64] a 2011 study in The Lancet concluded that traffic exposure is the single most serious preventable trigger of heart attack in the general public, as the cause of 7.4% of all attacks. [45] It is not possible to tell how much of this effect is due to the stress of being in traffic and how much is due to exposure to exhaust.[ citation needed ]
Since the study of the detrimental health effects of nanoparticles (nanotoxicology) is still in its infancy, and the nature and extent of negative health impacts from diesel exhaust continues to be discovered, it remains controversial whether the public health impact of diesels is higher than that of petrol-fueled vehicles. [65]
The types and quantities of nanoparticles can vary according to operating temperatures and pressures, the presence of an open flame, fundamental fuel type and fuel mixture, and even atmospheric mixtures. As such, the resulting types of nanoparticles from different engine technologies and even different fuels are not necessarily comparable. One study has shown that 95% of the volatile component of diesel nanoparticles is unburned lubricating oil. [66] Long-term effects still need to be further clarified, as well as the effects on susceptible groups of people with cardiopulmonary diseases.
Diesel engines can produce black soot (or more specifically diesel particulate matter) from their exhaust. The black smoke consists of carbon compounds that have not burned because of local low temperatures where the fuel is not fully atomized. These local low temperatures occur at the cylinder walls, and at the surface of large droplets of fuel. At these areas where it is relatively cold, the mixture is rich (contrary to the overall mixture which is lean). The rich mixture has less air to burn and some of the fuel turns into a carbon deposit. Modern car engines use a diesel particulate filter (DPF) to capture carbon particles and then intermittently burn them using extra fuel injected directly into the filter. This prevents carbon buildup at the expense of wasting a small quantity of fuel.[ citation needed ]
When starting from cold, the engine's combustion efficiency is reduced because the cold engine block draws heat out of the cylinder in the compression stroke. [67] The result is that fuel is not burned fully, resulting in blue and white smoke and lower power outputs until the engine has warmed. This is especially the case with indirect injection engines, which are less thermally efficient. With electronic injection, the timing and length of the injection sequence can be altered to compensate for this. Older engines with mechanical injection can have mechanical and hydraulic governor control to alter the timing, and multi-phase electrically controlled glow plugs, that stay on for a period after start-up to ensure clean combustion; the plugs are automatically switched to a lower power to prevent their burning out.[ citation needed ]
Wärtsilä states that there are two ways of forming smoke, on large diesel engines, one being fuel hitting metal and not having time to burn off. The other being, when too much fuel is in the combustion chamber.
Wärtsilä have tested an engine and compared smoke-output, when using conventional fuel system and common rail fuel system, the result shows improvement on all operation conditions when using the common rail system. [68]
This section is missing information about NOx emissions. They affect smog, ozone, acid rain, and pulmonary problems.(January 2017) |
Experiments in 2013 showed that diesel exhaust impaired bees' ability to detect the scent of oilseed rape flowers. [69]
Emissions from diesel engines contribute to the production of ground-level ozone, which can damage crops, trees, and other vegetation. Diesel exhaust also contributes to the formation of acid rain, which affects soil, lakes, and streams, and can enter the human food chain via water, produce, meat, and fish. [70]
Diesel exhaust plays a role in climate change. Reducing greenhouse gas (GHG) emissions from diesel engines through improved fuel economy or idle reduction strategies can help address climate change, improve energy security, and strengthen the economies of countries. [70] While diesel fuel contains slightly more carbon (2.68 kg CO2/litre) than petrol (2.31 kg CO2/litre), overall, the CO2 emissions of a diesel car tend to be lower due to higher efficiency. In use, on average, this equates to around 200 g CO2/km for petrol and 120 g CO2/km for diesel.
This section may rely excessively on sources too closely associated with the subject , potentially preventing the article from being verifiable and neutral.(October 2015) |
With emission standards tightening, diesel engines are having to become more efficient and have fewer pollutants in their exhaust.[ citation needed ] Moreover, in recent years the United States, Europe, and Japan have extended emissions control regulations from covering on-road vehicles to include farm vehicles and locomotives, marine vessels, and stationary generator applications. [71] Changing to a different fuel (i.e. dimethyl ether, and other bioethers as diethyl ether) [72] tends to be a very effective means to reduce pollutants such as NOx and CO. When running on dimethyl ether (DME) for instance, particulate matter emissions are near-nonexistent, and the use of diesel particulate filters could even be omitted. [73] Also, given that DME can be made from animal, food, and agricultural waste, it can even be carbon-neutral (unlike regular diesel). Mixing in bio ether (or other fuels such as hydrogen) [74] [75] into conventional diesel also tends to have a beneficial effect on the pollutants that are emitted. In addition to changing the fuel, US engineers have also come up with two other principles and distinct systems to all on-market products that meet the U.S. 2010 emissions criteria,[ citation needed ][ needs update ] selective non-catalytic reduction (SNCR), and exhaust gas recirculation (EGR). Both are in the exhaust system of diesel engines, and are further designed to promote efficiency.[ citation needed ]
Selective catalytic reduction (SCR) injects a reductant such as ammonia or urea — the latter aqueous, where it is known as diesel exhaust fluid (DEF) — into the exhaust of a diesel engine to convert nitrogen oxides (NOx) into gaseous nitrogen and water. SNCR systems have been prototyped that reduce 90% of the NOx in the exhaust system, with commercialized systems being somewhat lower.[ citation needed ] SCR systems do not necessarily need particulate matter (PM) filters; when SNCR and PM filters are combined, some engines have been shown to be 3-5% more fuel efficient.[ citation needed ] A disadvantage of the SCR system, in addition to added upfront development cost (which can be offset by compliance and improved performance),[ citation needed ] is the need to refill the reductant, the periodicity of which varies with the miles driven, load factors, and the hours used. [76] [ full citation needed ][ better source needed ][ third-party source needed ] The SNCR system is not as efficient at higher revolutions per minute (rpm).[ citation needed ] SCR is being optimized to have higher efficiency with broader temperatures, to be more durable, and to meet other commercial needs. [71]
Exhaust gas recirculation (EGR), on diesel engines, can be used to achieve a richer fuel to air mixture and a lower peak combustion temperature. Both effects reduce NOx emissions, but can negatively impact efficiency and the production of soot particles. The richer mix is achieved by displacing some of the intake air, but is still lean compared to petrol engines, which approach the stoichiometric ideal. The lower peak temperature is achieved by a heat exchanger that removes heat before re-entering the engine, and works due to the exhaust gases' higher specific heat capacity than air. With the greater soot production, EGR is often combined with a particulate matter (PM) filter in the exhaust. [77] [ full citation needed ] In turbocharged engines, EGR needs a controlled pressure differential across the exhaust manifold and intake manifold, which can be met by such engineering as use of a variable geometry turbocharger,[ citation needed ] which has inlet guide vanes on the turbine to build exhaust backpressure in the exhaust manifold directing exhaust gas to the intake manifold. [77] It also requires additional external piping and valving, and so requires additional maintenance.[ citation needed ] [78]
John Deere, the farm equipment manufacturer, is implementing a combined SCR-EGR design, in a 9-liter "inline 6" diesel engine that involves both system types, a PM filter and additional oxidation catalyst technologies. [79] [ better source needed ][ third-party source needed ] The combined system incorporates two turbochargers, the first on the exhaust manifold, with variable geometry and containing the EGR system; and a second a fixed geometry turbocharger. Recirculated exhaust gas and the compressed air from the turbochargers have separate coolers, and air merges before entering the intake manifold, and all subsystems are controlled by a central engine control unit that optimizes minimization of pollutants released in the exhaust gas. [79]
This section needs expansionwith: the further sourced content on such things as diesel particulate filters and use of alternate fuels, placed here with citations;: significant sentences only with citations, no more top-of-the-head content dumping. You can help by adding to it. (October 2015) |
A new technology being tested in 2016 has been created by Air Ink which collects carbon particles using a "Kaalink" cylindrical device that is retrofitted into a vehicle's exhaust system, after processing to remove heavy metals and carcinogens, the company plans to use the carbon to make ink. [80]
In India, the Chakr Dual Fuel Kit retrofits a diesel generator set to operate on a mixture of both gas and diesel, with 70% natural gas and 30% fossil fuel. [81]
There has been research into ways that troops in deserts can recover drinkable water from their vehicles' exhaust gases. [82] [83] [84] [85] [86]
composition can vary markedly with fuel composition, engine type, operating conditions ... combustion of petroleum fuel produces primarily carbon dioxide, water, and nitrogen ... The health risks lie in the small, invisible or poorly visible particles ... carbon (EC) core of diesel soot ... serves as a nucleus for condensation of organic compounds from unburned or incompletely burned fuel ... it still appears that nitrated PAHs are the most predominant bacterial mutagens
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ignored (help)New diesels produce similar nitrogen oxides to those bought 15 years ago. Typical modern diesel cars emit around 20 times more nitrogen oxides than petrol cars.
Much of the problem is down to EU emission standards, which have long allowed diesel engines to emit much more nitrogen dioxide than petrol ones.
However, vehicles registered from 2005–2010 emit similar or higher levels of NOx compared with vehicles before 1995. In this respect, NOx emissions from diesel cars have changed little over a period of about 20 years.
Diesel exhaust includes ... acetaldehyde; antimony compounds; arsenic; benzene; beryllium compounds; bis(2-ethylhexyl)phthalate; dioxins and dibenzofurans; formaldehyde; inorganic lead; mercury compounds; nickel; POM (including PAHs); and styrene.
High doses of di-2-ethylhexyl phthalate (DEHP), dibutyl phthalate (DBP), and benzylbutyl phthalate (BzBP) during the fetal period produced lowered testosterone levels, testicular atrophy, and Sertoli cell abnormalities in the male animals and, at higher doses, ovarian abnormalities in the female animals (Jarfelt et al., 2005; Lovekamp-Swan and Davis, 2003; McKee et al., 2004; NTP-CERHR, 2003a, 2003b, 2006).
Acute (short-term) exposure ... results in irritation of the eyes, mucous membranes, ... Chronic (long-term) exposure ... has resulted in effects on the peripheral and central nervous systems and the liver and kidney.
Concentration (ng/mg extract) ... Concentration (μg/g of particles)
the health damage associated with diesel vehicle emissions are …… at least 5 times greater than those associated with petrol vehicles.
After a week-long meeting of international experts, the International Agency for Research on Cancer (IARC), which is part of the World Health Organization (WHO), today classified diesel exhaust as probably carcinogenic to humans (Group 1), based on enough evidence that exposure is associated with an increased risk of lung cancer.
The scientific evidence was reviewed thoroughly by the Working Group and overall it was concluded that there was sufficient evidence in humans for the carcinogenicity of diesel exhaust. The Working Group found that diesel exhaust is a cause of lung cancer (sufficient evidence) and also noted a positive association (limited evidence) with an increased risk of bladder cancer
Exposure to diesel exhaust particulates is reasonably anticipated to be a human carcinogen, based on limited evidence of carcinogenicity from studies in humans and supporting evidence from studies in experimental animals and mechanistic studies.
Using U.S. EPA's revised draft 1999 Guidelines for Carcinogen Risk Assessment (U.S. EPA, 1999), diesel exhaust (DE) is likely to be carcinogenic to humans by inhalation from environmental exposures.
Particulate matter air pollution contributes to lung cancer incidence in Europe.
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: CS1 maint: others (link)Smoke is a suspension of airborne particulates and gases 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, but may also be used for pest control (fumigation), communication, defensive and offensive capabilities in the military, cooking, or smoking. 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.
In internal combustion engines, exhaust gas recirculation (EGR) is a nitrogen oxide (NOx) emissions reduction technique used in petrol/gasoline, diesel engines and some hydrogen engines. EGR works by recirculating a portion of an engine's exhaust gas back to the engine cylinders. The exhaust gas displaces atmospheric air and reduces O2 in the combustion chamber. Reducing the amount of oxygen reduces the amount of fuel that can burn in the cylinder thereby reducing peak in-cylinder temperatures. The actual amount of recirculated exhaust gas varies with the engine operating parameters.
A catalytic converter is an exhaust emission control device which converts toxic gases and pollutants in exhaust gas from an internal combustion engine into less-toxic pollutants by catalyzing a redox reaction. Catalytic converters are usually used with internal combustion engines fueled by gasoline or diesel, including lean-burn engines, and sometimes on kerosene heaters and stoves.
Soot is a mass of impure carbon particles resulting from the incomplete combustion of hydrocarbons. Soot is considered a hazardous substance with carcinogenic properties. Most broadly, the term includes all the particulate matter produced by this process, including black carbon and residual pyrolysed fuel particles such as coal, cenospheres, charred wood, and petroleum coke classified as cokes or char. It can include polycyclic aromatic hydrocarbons and heavy metals like mercury.
Vehicle emissions control is the study of reducing the emissions produced by motor vehicles, especially internal combustion engines. The primary emissions studied include hydrocarbons, volatile organic compounds, carbon monoxide, carbon dioxide, nitrogen oxides, particulate matter, and sulfur oxides. Starting in the 1950s and 1960s, various regulatory agencies were formed with a primary focus on studying the vehicle emissions and their effects on human health and the environment. As the worlds understanding of vehicle emissions improved, so did the devices used to mitigate their impacts. The regulatory requirements of the Clean Air Act, which was amended many times, greatly restricted acceptable vehicle emissions. With the restrictions, vehicles started being designed more efficiently by utilizing various emission control systems and devices which became more common in vehicles over time.
Exhaust gas or flue gas is emitted as a result of the combustion of fuels such as natural gas, gasoline (petrol), diesel fuel, fuel oil, biodiesel blends, or coal. According to the type of engine, it is discharged into the atmosphere through an exhaust pipe, flue gas stack, or propelling nozzle. It often disperses downwind in a pattern called an exhaust plume.
A fossil fuel power station is a thermal power station which burns a fossil fuel, such as coal, oil, or natural gas, to produce electricity. Fossil fuel power stations have machinery to convert the heat energy of combustion into mechanical energy, which then operates an electrical generator. The prime mover may be a steam turbine, a gas turbine or, in small plants, a reciprocating gas engine. All plants use the energy extracted from the expansion of a hot gas, either steam or combustion gases. Although different energy conversion methods exist, all thermal power station conversion methods have their efficiency limited by the Carnot efficiency and therefore produce waste heat.
IARC group 1 Carcinogens are substances, chemical mixtures, and exposure circumstances which have been classified as carcinogenic to humans by the International Agency for Research on Cancer (IARC). This category is used when there is sufficient evidence of carcinogenicity in humans. Exceptionally, an agent may be placed in this category when evidence of carcinogenicity in humans is less than sufficient, but when there is sufficient evidence of carcinogenicity in experimental animals and strong evidence in exposed humans that the agent (mixture) acts through a relevant mechanism of carcinogenicity.
In atmospheric chemistry, NOx is shorthand for nitric oxide and nitrogen dioxide, the nitrogen oxides that are most relevant for air pollution. These gases contribute to the formation of smog and acid rain, as well as affecting tropospheric ozone.
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 the atmosphere. There are many different types of air pollutants, such as gases, particulates 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 the natural environment or built environment. Air pollution can be caused by both human activities and natural phenomena.
Air pollution is the introduction of chemicals, particulate matter, or biological materials into the atmosphere that cause harm or discomfort to humans or other living organisms, or damage ecosystems. Health problems attributed to air pollution include premature death, cancer, organ failure, infections, behavioral changes, and other diseases. These health effects are not equally distributed across the U.S. population; there are demographic disparities by race, ethnicity, socioeconomic status, and education. Air pollution can derive from natural sources, such as wildfires and volcanoes, or from anthropogenic sources. Anthropogenic air pollution has affected the United States since the beginning of the Industrial Revolution.
A hydrogen internal combustion engine vehicle (HICEV) is a type of hydrogen vehicle using an internal combustion engine. Hydrogen internal combustion engine vehicles are different from hydrogen fuel cell vehicles. Instead, the hydrogen internal combustion engine is simply a modified version of the traditional gasoline-powered internal combustion engine. The absence of carbon means that no CO2 is produced, which eliminates the main greenhouse gas emission of a conventional petroleum engine.
Cerium(III) oxide, also known as cerium oxide, cerium trioxide, cerium sesquioxide, cerous oxide or dicerium trioxide, is an oxide of the rare-earth metal cerium. It has chemical formula Ce2O3 and is gold-yellow in color.
Pollution in California relates to the degree of pollution in the air, water, and land of the U.S. state of California. Pollution is defined as the addition of any substance or any form of energy to the environment at a faster rate than it can be dispersed, diluted, decomposed, recycled, or stored in some harmless form. The combination of three main factors is the cause of notable unhealthy levels of air pollution in California: the activities of over 39 million people, a mountainous terrain that traps pollution, and a warm climate that helps form ozone and other pollutants. Eight of the ten cities in the US with the highest year-round concentration of particulate matter between 2013 and 2015 were in California, and seven out of the ten cities in the US with the worst ozone pollution were also in California. Studies show that pollutants prevalent in California are linked to several health issues, including asthma, lung cancer, birth complications, and premature death. In 2016, Bakersfield, California recorded the highest level of airborne pollutants of any city in the United States.
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 California Statewide Truck and Bus Rule was initially adopted in December 2008 by the California Air Resources Board (CARB) and requires all heavy-duty diesel trucks and buses that operate in California to retrofit or replace engines in order to reduce diesel emissions. All privately and federally owned diesel-fueled trucks and buses, and privately and publicly owned school buses with a gross vehicle weight rating (GVWR) greater than 14,000 pounds, are covered by the regulation.
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. The main contributors to India's particulate air pollution include industrial and vehicular emissions, construction dust and debris, dependence on thermal power for electricity, waste burning, and use of wood and dung by low-income and rural households for cooking and heating. 51% of India's air 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.
The health of a mother directly affects the fetus during pregnancy. High levels of vehicle pollution where pregnant women reside can have adverse health effects on fetuses.
Non-exhaust emissions come from wearing down motor vehicle brake pads, tires, roads themselves, and unsettling of particles on the road. This particulate matter is made up of micrometre-sized particles and causes negative health effects, including respiratory disease and cancer. Very fine particulate matter has been linked to cardiovascular disease. Multiple epidemiological studies have demonstrated that particulate matter exposure is associated with acute respiratory infections, lung cancer, and chronic respiratory and cardiovascular disease. Researchers have also found correlations between exposure to fine particulate matter and fatality rates in previous coronavirus epidemics.
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.