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Emission standards are the legal requirements governing air pollutants released into the atmosphere. Emission standards set quantitative limits on the permissible amount of specific air pollutants that may be released from specific sources over specific timeframes. They are generally designed to achieve air quality standards and to protect human life. Different regions and countries have different standards for vehicle emissions.
Many emissions standards focus on regulating pollutants released by automobiles (motor cars) and other powered vehicles. Others regulate emissions from industry, power plants, small equipment such as lawn mowers and diesel generators, and other sources of air pollution.
The first automobile emissions standards were enacted in 1963 in the United States, mainly as a response to Los Angeles' smog problems. Three years later Japan enacted their first emissions rules, followed between 1970 and 1972 by Canada, Australia, and several European nations. [1] The early standards mainly concerned carbon monoxide (CO) and hydrocarbons (HC). Regulations on nitrogen oxide emissions (NOx) were introduced in the United States, Japan, and Canada in 1973 and 1974, with Sweden following in 1976 and the European Economic Community in 1977. These standards gradually grew more and more stringent but have never been unified. [2]
There are largely three main sets of standards: United States, Japanese, and European, with various markets mostly using these as their base. [2] Sweden, Switzerland, and Australia had separate emissions standards for many years but have since adopted the European standards. India, China, and other newer markets have also begun enforcing vehicle emissions standards (derived from the European requirements) in the twenty-first century, as growing vehicle fleets have given rise to severe air quality problems there, too.
This section needs additional citations for verification .(January 2009) |
An emission performance standard is a limit that sets thresholds above which a different type of vehicle emissions control technology might be needed. While emission performance standards have been used to dictate limits for conventional pollutants such as oxides of nitrogen and oxides of sulphur (NOx and SOx), [3] this regulatory technique may be used to regulate greenhouse gases, particularly carbon dioxide (CO2). In the US, this is given in pounds of carbon dioxide per megawatt-hour (lbs. CO2/MWhr), and kilograms CO2/MWhr elsewhere.
From 1 January 2024, all new vehicles in Morocco must comply with Euro 6b. [5]
South Africa's first clean fuels programme was implemented in 2006 with the banning of lead from petrol and the reduction of sulphur levels in diesel from 3,000 parts per million (ppm) to 500ppm, along with a niche grade of 50 ppm.
The Clean Fuels 2 standard, expected to begin in 2017, includes the reduction of sulphur to 10 ppm; the lowering of benzene from 5 percent to 1 percent of volume; the reduction of aromatics from 50 percent to 35 percent of volume; and the specification of olefins at 18 percent of volume.
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In Canada, the Canadian Environmental Protection Act, 1999 (CEPA 1999) transfers the legislative authority for regulating emissions from on-road vehicles and engines to Environment Canada from Transport Canada's Motor Vehicle Safety Act. The Regulations align emission standards with the U.S. federal standards and apply to light-duty vehicles (e.g., passenger cars), light-duty trucks (e.g., vans, pickup trucks, sport utility vehicles), heavy-duty vehicles (e.g., trucks and buses), heavy-duty engines and motorcycles. [6]
The United States has its own set of emissions standards that all new vehicles must meet. In the United States, emissions standards are managed by the Environmental Protection Agency (EPA). In 2014, the EPA published its "Tier 3" standards for cars, trucks and other motor vehicles, which tightened air pollution emission requirements and lowered the sulfur content in gasoline. [8]
EPA has separate regulations for small engines, such as groundskeeping equipment. The states must also promulgate miscellaneous emissions regulations in order to comply with the National Ambient Air Quality Standards. [9]
In December 2021 EPA issued new greenhouse gas standards for passenger cars and light trucks, effective for the 2023 vehicle model year. [10]
This section needs to be updated.(December 2022) |
Under federal law, the state of California is allowed to promulgate more stringent vehicle emissions standards (subject to EPA approval), and other states may choose to follow either the national or California standards. California had produced air quality standards prior to EPA, with severe air quality problems in the Los Angeles metropolitan area. LA is the country's second-largest city, by population, and relies much more heavily on automobiles and has less favorable meteorological conditions than the largest and third-largest cities (New York and Chicago). [11] [12]
Some states have areas within the state that require emissions testing while other cities within the state do not require emission testing. Arizona emissions testing locations are located primarily in the two largest metropolitan areas (Phoenix and Tucson). People outside of these areas are not required to submit their vehicle for testing as these areas are the only ones that have failed the air quality tests by the state.
California's emissions standards are set by the California Air Resources Board (CARB). By mid-2009, 16 other states had adopted CARB rules; [13] given the size of the California market plus these other states, many manufacturers choose to build to the CARB standard when selling in all 50 states. CARB's policies have also influenced EU emissions standards.[ citation needed ]
California is attempting to regulate greenhouse gas emissions from automobiles, but faces a court challenge from the federal government. The states are also attempting to compel the federal EPA to regulate greenhouse gas emissions, which as of 2007 it has declined to do. On 19 May 2009, news reports indicate that the Federal EPA will largely adopt California's standards on greenhouse gas emissions. [14]
California and several other western states have passed bills requiring performance-based regulation of greenhouse gases from electricity generation.
In an effort to decrease emissions from heavy-duty diesel engines faster, CARB's Carl Moyer Program funds upgrades that are in advance of regulations.
The California ARB standard for light vehicle emissions is a regulation of equipment first, with verification of emissions second. The property owner of the vehicle is not permitted to modify, improve, or innovate solutions in order to pass a true emissions-only standard set for their vehicle driven on public highways. Therefore, California's attempt at regulation of emissions is a regulation of equipment, not of air quality. Vehicle owners are excluded from modifying their property in any way that has not been extensively researched and approved by CARB and still operate them on public highways. [ neutrality is disputed ]
Since 1 January 2022, all new vehicles in Cambodia must comply with Euro 4. [29]
From 1 January 2027, all new vehicles in Cambodia must comply with Euro 5. [29]
Due to rapidly expanding wealth and prosperity, the number of coal power plants and cars on China's roads is rapidly growing, creating an ongoing pollution problem. China enacted its first emissions controls on automobiles in 2000, equivalent to Euro I standards. China's State Environmental Protection Administration (SEPA) upgraded emission controls again on 1 July 2004 to the Euro II standard. [30] More stringent emission standard, National Standard III, equivalent to Euro III standards, went into effect on 1 July 2007. [31] Plans were for Euro IV standards to take effect in 2010. Beijing introduced the Euro IV standard in advance on 1 January 2008, becoming the first city in mainland China to adopt this standard. [32]
From 1 January 2006, all new passenger cars with spark-ignition engines in Hong Kong must meet either Euro IV petrol standard, Japanese Heisei 17 standard or US EPA Tier 2 Bin 5 standard. For new passenger cars with compression-ignition engines, they must meet US EPA Tier 2 Bin 5 standard.
The current standard is Euro 6C, it has been phased in since 2019.
Bharat stage emission standards are emission standards instituted by the Government of India to regulate the output of air pollutants from internal combustion engine equipment, including motor vehicles. The standards and the timeline for implementation are set by the Central Pollution Control Board under the Ministry of Environment & Forests.
The standards, based on European regulations were first introduced in 2000. Progressively stringent norms have been rolled out since then. All new vehicles manufactured after the implementation of the norms have to be compliant with the regulations. By 2014, the country was under a combination of Euro 3 and Euro 4-based norms, with Euro 4 standards partly implemented in 13 major cities. Till April 2017, the entire country was under BS IV norms, which is based on Euro 4. [35]
As of now manufacturing and registration of BS VI vehicles has started, from April 2020 all BS VI manufacturing is mandatory, respectively. [35] [36]
Background
Starting 10 June 1968, the Japanese Government passed the Air Pollution Control Act [ ja ] which regulated all sources of air pollutants. As a result of the 1968 law, dispute resolutions were passed under the 1970 Air Pollution Dispute Resolution Act [ ja ]. As a result of the 1970 law, in 1973 the first installment of four sets of new emissions standards were introduced. Interim standards were introduced on 1 January 1975, and again for 1976. The final set of standards were introduced for 1978. [37] While the standards were introduced they were not made immediately mandatory, instead tax breaks were offered for cars which passed them. [38] The standards were based on those adopted by the original US Clean Air Act of 1970, but the test cycle included more slow city driving to correctly reflect the Japanese situation. [39] The 1978 limits for mean emissions during a "Hot Start Test" of CO, hydrocarbons, and NOx were 2.1 grams per kilometre (3.38 g/mi) of CO, 0.25 grams per kilometre (0.40 g/mi) of HC, and 0.25 grams per kilometre (0.40 g/mi) of NOx respectively. [39] Maximum limits are 2.7 grams per kilometre (4.35 g/mi) of CO, 0.39 grams per kilometre (0.63 g/mi) of HC, and 0.48 grams per kilometre (0.77 g/mi) of NOx. One interesting detail of the Japanese emissions standards was that they were introduced in a soft manner; that is, 1978 model year cars could be sold that did not meet the 1978 standards, but they would suffer various tax penalties. This gave manufacturers breathing room to properly engineer solutions and also incentivized fixing the best-selling models first, leading to smoother adoption of clean air standards and fewer drivability concerns than in many other markets.
The "10 - 15 Mode Hot Cycle" test, used to determine individual fuel economy ratings and emissions observed from the vehicle being tested, use a specific testing regime. [40] [41] [42]
In 1992, to cope with NOx pollution problems from existing vehicle fleets in highly populated metropolitan areas, the Ministry of the Environment adopted the Law Concerning Special Measures to Reduce the Total Amount of Nitrogen Oxides Emitted from Motor Vehicles in Specified Areas [ ja ], called in short The Motor Vehicle NOx Law. The regulation designated a total of 196 communities in the Tokyo, Saitama, Kanagawa, Osaka and Hyogo Prefectures as areas with significant air pollution due to nitrogen oxides emitted from motor vehicles. Under the Law, several measures had to be taken to control NOx from in-use vehicles, including enforcing emission standards for specified vehicle categories.
The regulation was amended in June 2001 to tighten the existing NOx requirements and to add PM control provisions. The amended rule is called the "Law Concerning Special Measures to Reduce the Total Amount of Nitrogen Oxides and Particulate Matter Emitted from Motor Vehicles in Specified Areas", or in short the Automotive NOx and PM Law.
The NOx and PM Law introduces emission standards for specified categories of in-use highway vehicles including commercial goods (cargo) vehicles such as trucks and vans, buses, and special purpose motor vehicles, irrespective of the fuel type. The regulation also applies to diesel powered passenger cars (but not to gasoline cars).
In-use vehicles in the specified categories must meet 1997/98 emission standards for the respective new vehicle type (in the case of heavy duty engines NOx = 4.5 g/kWh, PM = 0.25 g/kWh). In other words, the 1997/98 new vehicle standards are retroactively applied to older vehicles already on the road. Vehicle owners have two methods to comply:
Vehicles have a grace period, between 8 and 12 years from the initial registration, to comply. The grace period depends on the vehicle type, as follows:
Furthermore, the regulation allows fulfillment of its requirements to be postponed by an additional 0.5–2.5 years, depending on the age of the vehicle. This delay was introduced in part to harmonize the NOx and PM Law with the Tokyo diesel retrofit program.
The NOx and PM Law is enforced in connection with Japanese vehicle inspection program, where non-complying vehicles cannot undergo the inspection in the designated areas. This, in turn, may trigger an injunction on the vehicle operation under the Road Transport Vehicle Law.
Table chart for Gasoline-fueled or LPG- fueled Motor Vehicles, Diesel-Powered Motor Vehicles, and Vehicle Fuel Efficiency Standards. [43]
From 1 January 2024, all new vehicles in Thailand must comply with Euro 5. [44]
Diesel and gasoline sulphur content is regulated at 10 ppm. [45] Turkey currently follows Euro VI for heavy duty commercial vehicles, [46] and, in 2016 a couple of years after the EU, Turkey adopted Euro 6 for new types of light duty vehicles (LDV) and new types of passenger cars. [47] Turkey is planning to use the worldwide harmonized light vehicles test procedure (WLTP). [48]
However, despite these tailpipe emission standards for new vehicle types there are many older diesel vehicles, [49] no low-emission zones and no national limit on PM2.5 particulates so local pollution, including from older vehicles, is still a major health risk in some cities, such as Ankara. [50] [51] Concentrations of PM2.5 are 41 μg/m3 in Turkey, making it the country with the worst air pollution in Europe. [52] The regulation for testing of existing vehicle exhaust gases is Official Newspaper number 30004 published 11 March 2017.
An average of 135 g CO2/km for LDVs compared well with other countries in 2015, [53] however unlike the EU [54] there is no limit on carbon dioxide emissions. [55]
From 1 January 2022, all new cars in Vietnam must comply with Euro 5. [56]
Before the European Union began streamlining emissions standards, there were several different sets of rules. Members of the European Economic Community (EEC) had a unified set of rules, considerably laxer than those of the United States or Japan. These were tightened gradually, beginning on cars of over two liters displacement as the price increase would have less of an impact in this segment. [1] The ECE 15/05 norms (also known as the Luxemburg accord, strict enough to essentially require catalytic converters) began taking effect gradually: the initial step applied to cars of over 2000 cc in two stages, in October 1988 and October 1989. [2] There followed cars between 1.4 and 2.0 liters, in October 1991 and then October 1993. Cars of under 1400 cc had to meet two subsequent sets of regulations that applied in October 1992 and October 1994 respectively. [57] French and Italian car manufacturers, strongly represented in the small car category, had been lobbying heavily against these regulations throughout the 1980s. [58]
Within the EEC, Germany was a leader in regulating automobile emissions. Germany gave financial incentives to buyers of cars that met US or ECE standards, with lesser credits available to those that partially fulfilled the requirements. These incentives had a strong impact; only 6.5 percent of new cars registered in Germany in 1988 did not meet any emissions requirements and 67.3 percent were compliant with the strictest US or ECE standards. [1]
Sweden was one of the first countries to instill stricter rules (for 1975), placing severe limitations on the number of vehicles available there. These standards also caused drivability problems and steeply increased fuel consumption - in part because manufacturers could not justify the expenditure to meet specific regulations that applied only in one very small market. In 1982, the European Community calculated that the Swedish standards increased fuel consumption by 9 percent, while it made cars 2.5 percent more expensive. [59] For 1983 Switzerland (and then Australia) joined in the same set of regulations, which gradually increased the number of certified engines. [60] One problem with the strict standards was that they did not account for catalyzed engines, meaning that vehicles thus equipped had to have the catalytic converters removed before they could be legally registered.
In 1985 the first catalyzed cars entered certain European markets such as Germany. At first, the availability of unleaded petrol was limited and sales were small. In Sweden, catalyzed vehicles became allowed in 1987, benefitting from a tax rebate to boost sales. [61] By 1989 the Swiss/Swedish emissions rules were tightened to the point that non-catalyzed cars were no longer able to be sold. In early 1989 the BMW Z1 was introduced, only available with catalyzed engines. This was a problem in some places like Portugal, where unleaded fuel was still almost non-existent, although European standards required unleaded gasoline to be "available" in every country by 1 October 1989. [62]
The main source of greenhouse gas emissions in the European Union is transportation. In 2019, it contributes to about 31% of global emissions and 24% of emissions in the EU. In addition, up to the COVID-19 pandemic, emissions have only increased in the transport economic sector. [63] [64] In 2019, about 95% of the fuel came from fossil sources. [65]
The European Union has its own set of emissions standards that all new vehicles must meet. Currently, standards are set for all road vehicles, trains, barges and 'nonroad mobile machinery' (such as tractors). No standards apply to seagoing ships or airplanes.
EU Regulation No 443/2009 set an average CO2 emissions target for new passenger cars of 130 grams per kilometre. The target was gradually phased in between 2012 and 2015. A target of 95 grams per kilometre applies from 2021.
For light commercial vehicle, an emissions target of 175 g/km applies from 2017, and 147 g/km from 2020, [66] a reduction of 16%.
The EU introduced Euro 4 effective 1 January 2008, Euro 5 effective 1 January 2010, and Euro 6 effective 1 January 2014. These dates had been postponed for two years to give oil refineries the opportunity to modernize their plants.
From January 2022, all new light vehicles must comply with Euro 6d. From 1 January 2023, all new motorcycles must comply with Euro 5.
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Several local authorities in the UK have introduced Euro 4 or Euro 5 emissions standards for taxis and licensed private hire vehicles to operate in their area. [68] [69] [70] Emissions tests on diesel cars have not been carried out during MOTs in Northern Ireland for 12 years, despite being legally required. [71]
From January 2022, all new light vehicles must comply with Euro 6d. [72] From 1 January 2023, all new motorcycles must comply with Euro 5. [73]
Australian noxious emission standards are based on European regulations for light-duty and heavy-duty (heavy goods) vehicles, with acceptance of selected US and Japanese standards. The current policy is to fully harmonize Australian regulations with United Nations (UN) and Economic Commission for Europe (ECE) standards. In November 2013, the first stage of the stringent Euro 5 emission standards for light vehicles was introduced, which includes cars and light commercial vehicles. [74] The development of emission standards for highway vehicles and engines is coordinated by the National Transport Commission (NTC) and the regulations—Australian Design Rules (ADR)—are administered by the Department of Infrastructure and Transport. [75] [76]
All new vehicles manufactured or sold in the country must comply with the standards, which are tested by running the vehicle or engine in a standardized test cycle. [77]
In April 2023, the Australian government released its National Electric Vehicle Strategy, which included a commitment to introduce a Fuel Efficiency Standard to address greenhouse gas emissions. [78] The government undertook consultation on the model for the standard in April and May 2023, and they intend to introduce legislation by the end of 2023 [79] Research commissioned by environmental NGO Solar Citizens has calculated that a Fuel Efficiency Standard that started at 95g CO2/km and reduced to 0g CO2/km over ten years would save Australian motorists $11b over the first five years. [80]
From December 2025, all new vehicles sold in Australia will have to comply with Euro 6d. [81]
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.
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.
Selective catalytic reduction (SCR) means of converting nitrogen oxides, also referred to as NO
x with the aid of a catalyst into diatomic nitrogen, and water. A reductant, typically anhydrous ammonia, aqueous ammonia, or a urea solution, is added to a stream of flue or exhaust gas and is reacted onto a catalyst. As the reaction drives toward completion, nitrogen, and carbon dioxide, in the case of urea use, are produced.
The New European Driving Cycle (NEDC) was a driving cycle, last updated in 1997, designed to assess the emission levels of car engines and fuel economy in passenger cars. It is also referred to as MVEG cycle.
Diesel exhaust fluid 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 in the diesel exhaust emissions from a diesel engine.
A driving cycle is a series of data points representing the speed of a vehicle versus time.
The European emission standards are vehicle emission standards for pollution from the use of new land surface vehicles sold in the European Union and European Economic Area member states and the United Kingdom, and ships in EU waters. The standards are defined in a series of European Union directives staging the progressive introduction of increasingly stringent standards.
The fuel economy of an automobile relates to the distance traveled by a vehicle and the amount of fuel consumed. Consumption can be expressed in terms of the volume of fuel to travel a distance, or the distance traveled per unit volume of fuel consumed. Since fuel consumption of vehicles is a significant factor in air pollution, and since the importation of motor fuel can be a large part of a nation's foreign trade, many countries impose requirements for fuel economy.
A portable emissions measurement system (PEMS) is a vehicle emissions testing device that is small and light enough to be carried inside or moved with a motor vehicle that is being driven during testing, rather than on the stationary rollers of a dynamometer that only simulates real-world driving.
The Not-To-Exceed (NTE) standard promulgated by the United States Environmental Protection Agency (EPA) ensures that heavy-duty truck engine emissions are controlled over the full range of speed and load combinations commonly experienced in use. NTE establishes an area under the torque curve of an engine where emissions must not exceed a specified value for any of the regulated pollutants. The NTE test procedure does not involve a specific driving cycle of any specific length. Rather it involves driving of any type that could occur within the bounds of the NTE control area, including operation under steady-state or transient conditions and under varying ambient conditions. Emissions are averaged over a minimum time of thirty seconds and then compared to the applicable NTE emission limits.
United States vehicle emission standards are set through a combination of legislative mandates enacted by Congress through Clean Air Act (CAA) amendments from 1970 onwards, and executive regulations managed nationally by the Environmental Protection Agency (EPA), and more recently along with the National Highway Traffic Safety Administration (NHTSA). These standards cover tailpipe pollution, including carbon monoxide, nitrogen oxides, and particulate emissions, and newer versions have incorporated fuel economy standards. However they lag behind European emission standards, which limit air pollution from brakes and tires.
Bharat stage emission standards (BSES) are emission standards instituted by the Government of India to regulate the output of air pollutants from compression ignition engines and Spark-ignition engines equipment, including motor vehicles. The standards and the timeline for implementation are set by the Central Pollution Control Board under the Ministry of Environment, Forest and Climate Change.
The California Smog Check Program requires vehicles that were manufactured in 1976 or later to participate in the biennial smog check program in participating counties. The program's stated aim is to reduce air pollution from vehicles by ensuring that cars with excessive emissions are repaired in accordance with federal and state guidelines. With some exceptions, gasoline-powered vehicles, hybrid vehicles, and alternative-fuel vehicles that are eight model-years old or newer are not required to participate; instead, these vehicles pay a smog abatement fee for the first 8 years in place of being required to pass a smog check. The eight-year exception does not apply to nonresident vehicles being registered in California for the first time, diesel vehicles 1998 model or newer and weighing 14,000 lbs or less, or specially constructed vehicles 1976 and newer. The program is a joint effort between the California Air Resources Board, the California Bureau of Automotive Repair, and the California Department of Motor Vehicles.
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.
Mobile source air pollution includes any air pollution emitted by motor vehicles, airplanes, locomotives, and other engines and equipment that can be moved from one location to another. Many of these pollutants contribute to environmental degradation and have negative effects on human health. To prevent unnecessary damage to human health and the environment, environmental regulatory agencies such as the U.S. Environmental Protection Agency have established policies to minimize air pollution from mobile sources. Similar agencies exist at the state level. Due to the large number of mobile sources of air pollution, and their ability to move from one location to another, mobile sources are regulated differently from stationary sources, such as power plants. Instead of monitoring individual emitters, such as an individual vehicle, mobile sources are often regulated more broadly through design and fuel standards. Examples of this include corporate average fuel economy standards and laws that ban leaded gasoline in the United States. The increase in the number of motor vehicles driven in the U.S. has made efforts to limit mobile source pollution challenging. As a result, there have been a number of different regulatory instruments implemented to reach the desired emissions goals.
The Worldwide harmonized Light vehicles Test Procedure (WLTP) is a global driving cycle standard for determining the levels of pollutants, CO2 emission standards and fuel consumption of conventional internal combustion engine (ICE) and hybrid automobiles, as well as the all-electric range of plug-in electric vehicles.
The Volkswagen emissions scandal, sometimes known as Dieselgate or Emissionsgate, began in September 2015, when the United States Environmental Protection Agency (EPA) issued a notice of violation of the Clean Air Act to German automaker Volkswagen Group. The agency had found that Volkswagen had intentionally programmed turbocharged direct injection (TDI) diesel engines to activate their emissions controls only during laboratory emissions testing, which caused the vehicles' NOx output to meet US standards during regulatory testing. However, the vehicles emitted up to 40 times more NOx in real-world driving. Volkswagen deployed this software in about 11 million cars worldwide, including 500,000 in the United States, in model years 2009 through 2015.
A defeat device is any motor vehicle hardware, software, or design that interferes with or disables emissions controls under real-world driving conditions, even if the vehicle passes formal emissions testing. The term appears in the US Clean Air Act and European Union regulations, to describe anything that prevents an emissions control system from working, and applies as well to power plants or other air pollution sources, as to automobiles.
From 2014 onwards, software which manipulated air pollution tests was discovered in vehicles from some car makers; the software recognized when the standardized emissions test was being done, and adjusted the engine to emit less during the test. The cars emitted much higher levels of pollution under real-world driving conditions. Some cars' emissions were higher even though there was no manipulated software.
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