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Sunday, May 19, 2024

Inhalant

From Wikipedia, the free encyclopedia
 
Inhalant use
A man huffing an inhalant

SpecialtyToxicology
Complications
Differential diagnosisAlcoholism, inhaled anesthetics, marijuana abuse, tobacco smoking, crack cocaine, methamphetamines, medical inhalants, chasing the dragon

Inhalants are a broad range of household and industrial chemicals whose volatile vapors or pressurized gases can be concentrated and breathed in via the nose or mouth to produce intoxication, in a manner not intended by the manufacturer. They are inhaled at room temperature through volatilization (in the case of gasoline or acetone) or from a pressurized container (e.g., nitrous oxide or butane), and do not include drugs that are sniffed after burning or heating. For example, amyl nitrite (poppers), gasoline, nitrous oxide and toluene – a solvent widely used in contact cement, permanent markers, and certain types of glue – are considered inhalants, but smoking tobacco, cannabis, and crack cocaine are not, even though these drugs are inhaled as smoke or vapor.

While a few inhalants are prescribed by medical professionals and used for medical purposes, as in the case of inhaled anesthetics and nitrous oxide (an anxiolytic and pain relief agent prescribed by dentists), this article focuses on inhalant use of household and industrial propellants, glues, fuels, and other products in a manner not intended by the manufacturer, to produce intoxication or other psychoactive effects. These products are used as recreational drugs for their intoxicating effect. According to a 1995 report by the National Institute on Drug Abuse, the most serious inhalant use occurs among homeless children and teenagers who "... live on the streets completely without family ties." Inhalants are the only substance used more by younger teenagers than by older teenagers. Inhalant users inhale vapor or aerosol propellant gases using plastic bags held over the mouth or by breathing from a solvent-soaked rag or an open container. The practices are known colloquially as "sniffing", "huffing" or "bagging".

The effects of inhalants range from an alcohol-like intoxication and intense euphoria to vivid hallucinations, depending on the substance and the dose. Some inhalant users are injured due to the harmful effects of the solvents or gases or due to other chemicals used in the products that they are inhaling. As with any recreational drug, users can be injured due to dangerous behavior while they are intoxicated, such as driving under the influence. In some cases, users have died from hypoxia (lack of oxygen), pneumonia, heart failure, cardiac arrest, or aspiration of vomit. Brain damage is typically seen with chronic long-term use of solvents as opposed to short-term exposure.

While legal when used as intended, in England, Scotland, and Wales it is illegal to sell inhalants to persons likely to use them as an intoxicant. As of 2017, thirty-seven US states impose criminal penalties on some combination of sale, possession or recreational use of various inhalants. In 15 of these states, such laws apply only to persons under the age of 18.

Overview

Safety Category Sub category Psychoactive effect ICD-10 Examples Example image
Medical Nitrites
Dissociative T65.3
T65.5
Alkyl nitrites (poppers such as amyl nitrite)
Medical NOx
Dissociative T59.0 Nitrous oxide (found in whipped cream canisters)
Medical (historical) Haloalkanes
Depressant T53 Hydrofluorocarbons, chlorofluorocarbons (including many aerosols and propellants), chloroethanes (chloroethane, 1,1,1-Trichloroethane), trichloroethylene, chloroform (the latter two being antiquated inhalational anaesthetics)
Toxic Hydrocarbons Aliphatic hydrocarbons Dissociative T52.0 Petroleum products (gasoline and kerosene), propane, butane
Aromatic hydrocarbons Dissociative T52.1
T52.2
Toluene (used in paint thinner and model glue), xylene
Toxic Ketones
Depressant T52.4 Acetone (used in nail polish remover)

Medical inhalants

Tanks of medical-grade nitrous oxide.

A small number of recreational inhalant drugs are pharmaceutical products that are used illicitly.

Several medical anesthetics are used as recreational drugs, including diethyl ether (a drug that is no longer used medically, due to its high flammability and the development of safer alternatives) and nitrous oxide, which is widely used in the 2010s by dentists as an anti-anxiety drug during dental procedures. Diethyl ether has a long history of use as a recreational drug. The effects of ether intoxication are similar to those of alcohol intoxication, but more potent. Also, due to NMDA antagonism, the user may experience all the psychedelic effects present in classical dissociatives such as ketamine in the forms of thought loops and the feeling of the mind being disconnected from one's body. Nitrous oxide is a dental anesthetic that is used as a recreational drug, either by users who have access to medical-grade gas canisters (e.g., dental hygienists or dentists) or by using the gas contained in whipped cream aerosol containers. Nitrous oxide inhalation can cause pain relief, depersonalization, derealization, dizziness, euphoria, and some sound distortion.

Recreational use

Liquids

Alkyl nitrites
A selection of poppers
Legality

The sale of alkyl nitrite-based poppers was banned in Canada in 2013. Although not considered a narcotic and not illegal to possess or use, they are considered a drug. Sales that are not authorized can now be punished with fines and prison. Since 2007, reformulated poppers containing isopropyl nitrite are sold in Europe because only isobutyl nitrite is prohibited. In France, the sale of products containing butyl nitrite, pentyl nitrite, or isomers thereof, has been prohibited since 1990 on grounds of danger to consumers. In 2007, the government extended this prohibition to all alkyl nitrites that were not authorized for sale as drugs. After litigation by sex shop owners, this extension was quashed by the Council of State on the grounds that the government had failed to justify such a blanket prohibition: according to the court, the risks cited, concerning rare accidents often following abnormal usage, rather justified compulsory warnings on the packaging.

In the United Kingdom, poppers are widely available and frequently (legally) sold in gay clubs/bars, sex shops, drug paraphernalia head shops, over the Internet and on markets. It is illegal under Medicines Act 1968 to sell them advertised for human consumption, and to bypass this, they are usually sold as odorizers. In the U.S., originally marketed as a prescription drug in 1937, amyl nitrite remained so until 1960, when the Food and Drug Administration removed the prescription requirement due to its safety record. This requirement was reinstated in 1969, after observation of an increase in recreational use. Other alkyl nitrites were outlawed in the U.S. by Congress through the Anti-Drug Abuse Act of 1988. The law includes an exception for commercial purposes. The term commercial purpose is defined to mean any use other than for the production of consumer products containing volatile alkyl nitrites meant for inhaling or otherwise introducing volatile alkyl nitrites into the human body for euphoric or physical effects. The law came into effect in 1990. Visits to retail outlets selling these products reveal that some manufacturers have since reformulated their products to abide by the regulations, through the use of the legal cyclohexyl nitrite as the primary ingredient in their products, which are sold as video head cleaners, polish removers, or room odorants.

Safety

Ingestion of alkyl nitrites can cause methemoglobinemia, and by inhalation it has not been ruled out.

Gases

Nitrous oxide
The canister on the left is whipped cream, a product which is pressurized with nitrous oxide. The two canisters on the right contain 'flavoured' oxygen.

Nitrous oxide can be categorized as a dissociative drug, as it can cause visual and auditory hallucinations. Anesthetic gases used for surgery, such as nitrous oxide or enflurane, are believed to induce anesthesia primarily by acting as NMDA receptor antagonists, open-channel blockers that bind to the inside of the calcium channels on the outer surface of the neuron, and provide high levels of NMDA receptor blockade for a short period of time.

This makes inhaled anesthetic gases different from other NMDA antagonists, such as ketamine, which bind to a regulatory site on the NMDA-sensitive calcium transporter complex and provide slightly lower levels of NMDA blockade, but for a longer and much more predictable duration. This makes a deeper level of anesthesia achievable more easily using anesthetic gases but can also make them more dangerous than other drugs used for this purpose.

Legality
Nitrous oxide "whippets" are small aerosol containers designed for charging whipped cream dispensers.
A nitrous oxide "cracker" device, for releasing the gas from whipped cream aerosol chargers.

In the United States, possession of nitrous oxide is legal under federal law and is not subject to DEA purview. It is, however, regulated by the Food and Drug Administration under the Food Drug and Cosmetics Act; prosecution is possible under its "misbranding" clauses, prohibiting the sale or distribution of nitrous oxide for the purpose of human consumption as a recreational drug. Many states have laws regulating the possession, sale, and distribution of nitrous oxide. Such laws usually ban distribution to minors or limit the amount of nitrous oxide that may be sold without a special license. For example, in the state of California, possession for recreational use is prohibited and qualifies as a misdemeanor. In New Zealand, the Ministry of Health has warned that nitrous oxide is a prescription medicine, and its sale or possession without a prescription is an offense under the Medicines Act. This statement would seemingly prohibit all non-medicinal uses of the chemical, though it is implied that only recreational use will be legally targeted. In India, for general anesthesia purposes, nitrous oxide is available as Nitrous Oxide IP. India's gas cylinder rules (1985) prohibit the transfer of gas from one cylinder to another for breathing purposes. Because India's Food & Drug Authority (FDA-India) rules state that transferring a drug from one container to another (refilling) is equivalent to manufacturing, anyone found doing so must possess a drug manufacturing license.

Safety

Nitrous oxide is thought to be particularly non-toxic, though heavy long-term use can lead to a variety of serious health problems linked to the destruction of vitamin B12 and folic acid.

Safety

In contrast, a few inhalants like amyl nitrite and diethyl ether have medical applications and are not toxic in the same sense as solvents, though they can still be dangerous when used recreationally.

Non-medical inhalants

Ethanol (the alcohol which is normally drunk) is sometimes inhaled.

The ethanol must be converted from liquid into gaseous state (vapor) or aerosol (mist), in some cases using a nebulizer, a machine that agitates the liquid into an aerosol. The sale of nebulizers for inhaling ethanol was banned in some US states due to safety concerns.

Toxic inhalants

Most inhalant drugs that are used non-medically are ingredients in household or industrial chemical products that are not intended to be concentrated and inhaled.

Solvents

A wide range of volatile solvents intended for household or industrial use are inhaled as recreational drugs. This includes petroleum products (gasoline and kerosene), toluene (used in paint thinner, permanent markers, contact cement and model glue), and acetone (used in nail polish remover). These solvents vaporize at room temperature.

Legality

Solvent glue
Contact cement, a fast-drying glue, is widely used as an inhalant, as it typically contains solvents such as toluene which vaporize at room temperature.

Even though solvent glue is normally a legal product, there is a 1983 case where a court ruled that supplying glue to children is illegal. Khaliq v HM Advocate was a Scottish criminal case decided by the High Court of Justiciary on appeal, in which it was decided that it was an offense at common law to supply glue-sniffing materials that were otherwise legal in the knowledge that they would be used recreationally by children. Two shopkeepers in Glasgow were arrested and charged for supplying children with "glue-sniffing kits" consisting of a quantity of petroleum-based glue in a plastic bag. They argued there was nothing illegal about the items that they had supplied. On appeal, the High Court took the view that, even though glue and plastic bags might be perfectly legal, everyday items, the two shopkeepers knew perfectly well that the children were going to use the articles as inhalants and the charge on the indictment should stand. When the case came to trial at Glasgow High Court the two were sentenced to three years' imprisonment.

As of 2023, in England, Scotland, and Wales it is illegal to sell inhalants, including solvent glues, to persons of any age likely to use them as an intoxicant. As of 2017, thirty-seven US states impose criminal penalties on some combination of sale, possession or recreational use of various inhalants. In 15 of these states, such laws apply only to persons under the age of 18.

Gasoline

Gasoline sniffing can cause lead poisoning, in locations where leaded gas is not banned.

Toluene

Toluene can damage myelin.

History

Whiteboard marker on a clapperboard.

Until the early 1990s, the most common solvents that were used for the ink in permanent markers were toluene and xylene. These two substances are both harmful and characterized by a very strong smell. Today, the ink is usually made on the basis of alcohols (e.g. 1-Propanol, 1-butanol, diacetone alcohol and cresols).

Organochlorine solvents are particularly hazardous; many of these are now restricted in developed countries due to their environmental impact.

Gases

Computer-cleaning dusters are dangerous to inhale because the gases expand and cool rapidly upon being sprayed.

A number of gases intended for household or industrial use are inhaled as recreational drugs. This includes chlorofluorocarbons used in aerosols and propellants (e.g., aerosol hair spray, aerosol deodorant). A gas used as a propellant in whipped cream aerosol containers, nitrous oxide, is used as a recreational drug. Pressurized canisters of propane and butane gas, both of which are intended for use as fuels, are used as inhalants.

Legality

Propellant gases

"New Jersey... prohibits selling or offering to sell minors products containing chlorofluorocarbon that is used in refrigerant."

Dangers

Statistics on deaths caused by heavy inhalant use are difficult to determine. It may be severely under-reported because death is often attributed to a discrete event such as a stroke or a heart attack, even if the event happened because of inhalant use. Inhalant use was mentioned on 144 death certificates in Texas during the period 1988–1998 and was reported in 39 deaths in Virginia between 1987 and 1996 from acute voluntary exposure to used inhalants.

Chronic solvent-induced encephalopathy

Chronic solvent-induced encephalopathy (CSE) is a condition induced by long-term exposure to organic solvents, often—but not always—in the workplace, that lead to a wide variety of persisting sensorimotor polyneuropathies and neurobehavioral deficits even after solvent exposure has been removed.

Sudden sniffing death syndrome

Sudden sniffing death syndrome, first described by Millard Bass in 1970, is commonly known as SSDS.

Solvents have many potential risks in common, including pneumonia, cardiac failure or arrest, and aspiration of vomit. The inhaling of some solvents can cause hearing loss, limb spasms, and damage to the central nervous system and brain. Serious but potentially reversible effects include liver and kidney damage and blood-oxygen depletion. Death from inhalants is generally caused by a very high concentration of fumes. Deliberately inhaling solvents from an attached paper or plastic bag or in a closed area greatly increases the chances of suffocation. Brain damage is typically seen with chronic long-term use as opposed to short-term exposure. Parkinsonism (see: Signs and symptoms of Parkinson's disease) has been associated with huffing.

The middle container is cooking spray, a household product, which is used as an inhalant.

Female inhalant users who are pregnant may have adverse effects on the fetus, and the baby may be smaller when it is born and may need additional health care (similar to those seen with alcohol – fetal alcohol syndrome). There is some evidence of birth defects and disabilities in babies born to women who sniffed solvents such as gasoline.

In the short term, death from solvent use occurs most commonly from aspiration of vomit while unconscious or from a combination of respiratory depression and hypoxia,

Inhaling butane gas can cause drowsiness, unconsciousness, asphyxia, and cardiac arrhythmia. Butane is the most commonly misused volatile solvent in the UK and caused 52% of solvent-related deaths in 2000. When butane is sprayed directly into the throat, the jet of fluid can cool rapidly to −20 °C by adiabatic expansion, causing prolonged laryngospasm.

Some inhalants can also indirectly cause sudden death by cardiac arrest, in a syndrome known as "sudden sniffing death". The anaesthetic gases present in the inhalants appear to sensitize the user to adrenaline and, in this state, a sudden surge of adrenaline (e.g., from a frightening hallucination or run-in with aggressors), may cause fatal cardiac arrhythmia.

Furthermore, the inhalation of any gas that is capable of displacing oxygen in the lungs (especially gases heavier than oxygen) carries the risk of hypoxia as a result of the very mechanism by which breathing is triggered. Since reflexive breathing is prompted by elevated carbon dioxide levels (rather than diminished blood oxygen levels), breathing a concentrated, relatively inert gas (such as computer-duster tetrafluoroethane or nitrous oxide) that removes carbon dioxide from the blood without replacing it with oxygen will produce no outward signs of suffocation even when the brain is experiencing hypoxia. Once full symptoms of hypoxia appear, it may be too late to breathe without assistance, especially if the gas is heavy enough to lodge in the lungs for extended periods. Even completely inert gases, such as argon, can have this effect if oxygen is largely excluded.

Patterns of use

Inhalant drugs are often used by children, teenagers, incarcerated or institutionalized people, and impoverished people, because these solvents and gases are ingredients in hundreds of legally available, inexpensive products, such as deodorant sprays, hair spray, contact cement and aerosol air fresheners. However, most users tend to be "... adolescents (between the ages of 12 and 17)." In some countries, chronic, heavy inhalant use is concentrated in marginalized, impoverished communities. Young people who become used to heavy amounts of inhalants chronically are also more likely to be those who are isolated from their families and community. The article "Epidemiology of Inhalant Abuse: An International Perspective" notes that "[t]he most serious form of obsession with inhalant use probably occurs in countries other than the United States where young children live on the streets completely without family ties. These groups almost always use inhalants at very high levels (Leal et al. 1978). This isolation can make it harder to keep in touch with the sniffer and encourage him or her to stop sniffing."

The article also states that "... high [inhalant use] rates among barrio Hispanics almost undoubtedly are related to the poverty, lack of opportunity, and social dysfunction that occur in barrios" and states that the "... same general tendency appears for Native-American youth" because "... Indian reservations are among the most disadvantaged environments in the United States; there are high rates of unemployment, little opportunity, and high rates of alcoholism and other health problems." There are a wide range of social problems associated with inhalant use, such as feelings of distress, anxiety and grief for the community; violence and damage to property; violent crime; stresses on the juvenile justice system; and stresses on youth agencies and support services.

Africa and Asia

Glue and gasoline (petrol) sniffing is also a problem in parts of Africa, especially with street children. In India and South Asia, three of the most widely used inhalants are the Dendrite brand and other forms of contact adhesives and rubber cement manufactured in Kolkata, and toluenes in paint thinners. Genkem is a brand of glue, which had become the generic name for all the glues used by glue-sniffing children in Africa before the manufacturer replaced n-hexane in its ingredients in 2000.

The United Nations Office on Drugs and Crime has reported that glue sniffing is at the core of "street culture" in Nairobi, Kenya, and that the majority of street children in the city are habitual solvent users. Research conducted by Cottrell-Boyce for the African Journal of Drug and Alcohol Studies found that glue sniffing amongst Kenyan street children was primarily functional – dulling the senses against the hardship of life on the street – but it also provided a link to the support structure of the "street family" as a potent symbol of shared experience.

Similar incidents of glue sniffing among destitute youth in the Philippines have also been reported, most commonly from groups of street children and teenagers collectively known as "Rugby" boys, which were named after a brand of toluene-laden contact cement. Other toluene-containing substances have also been used, most notably the Vulca Seal brand of roof sealants. Bostik Philippines, which currently owns the Rugby and Vulca Seal brands, has since responded to the issue by adding bitterants such as mustard oil to their Rugby line, as well as reformulating it by replacing toluene with xylene. Several other manufacturers have also followed suit.

Another very common inhalant is Erase-X, a correction fluid that contains toluene. It has become very common for school and college students to use it, because it is easily available in stationery shops in India. This fluid is also used by street and working children in Delhi.

Europe and North America

In the UK, marginalized youth use a number of inhalants, such as solvents and propellants. In Russia and Eastern Europe, gasoline sniffing became common on Russian ships following attempts to limit the supply of alcohol to ship crews in the 1980s. The documentary Children Underground depicts the huffing of a solvent called Aurolac (a product used in chroming) by Romanian homeless children. During the interwar period, the inhalation of ether (etheromania) was widespread in some regions of Poland, especially in Upper Silesia. Tens of thousands of people were affected by this problem.

In Canada, Native children in the isolated Northern Labrador community of Davis Inlet were the focus of national concern in 1993, when many were found to be sniffing gasoline. The Canadian and provincial Newfoundland and Labrador governments intervened on a number of occasions, sending many children away for treatment. Despite being moved to the new community of Natuashish in 2002, serious inhalant use problems have continued. Similar problems were reported in Sheshatshiu in 2000 and also in Pikangikum First Nation. In 2012, the issue once again made the news media in Canada. In Mexico, the inhaling of a mixture of gasoline and industrial solvents, known locally as "Activo" or "Chemo", has risen in popularity among the homeless and among the street children of Mexico City in recent years. The mixture is poured onto a handkerchief and inhaled while held in one's fist.

In the US, ether was used as a recreational drug during the 1930s Prohibition era, when alcohol was made illegal. Ether was either sniffed or drunk and, in some towns, replaced alcohol entirely. However, the risk of death from excessive sedation or overdose is greater than that with alcohol, and ether drinking is associated with damage to the stomach and gastrointestinal tract. Use of glue, paint and gasoline became more common after the 1950s. Model airplane glue-sniffing as problematic behavior among youth was first reported in 1959 and increased in the 1960s. Use of aerosol sprays became more common in the 1980s, as older propellants such as CFCs were phased out and replaced by more environmentally friendly compounds such as propane and butane. Most inhalant solvents and gases are not regulated under drug laws such as the United States Controlled Substances Act. However, many US states and Canadian cities have placed restrictions on the sale of some solvent-containing products to minors, particularly for products widely associated with sniffing, such as model cement. The practice of inhaling such substances is sometimes colloquially referred to as huffing, sniffing (or glue sniffing), dusting, or chroming.

Australia

Gasoline (also known as petrol) is used as an inhalant in impoverished communities.

Australia has long faced a petrol (gasoline) sniffing problem in isolated and impoverished aboriginal communities. Although some sources argue that sniffing was introduced by United States servicemen stationed in the nation's Top End during World War II or through experimentation by 1940s-era Cobourg Peninsula sawmill workers, other sources claim that inhalant abuse (such as glue inhalation) emerged in Australia in the late 1960s. Chronic, heavy petrol sniffing appears to occur among remote, impoverished indigenous communities, where the ready accessibility of petrol has helped to make it a common addictive substance.

In Australia, petrol sniffing now occurs widely throughout remote Aboriginal communities in the Northern Territory, Western Australia, northern parts of South Australia, and Queensland. The number of people sniffing petrol goes up and down over time as young people experiment or sniff occasionally. "Boss", or chronic, sniffers may move in and out of communities; they are often responsible for encouraging young people to take it up.

A 1983 survey of 4,165 secondary students in New South Wales showed that solvents and aerosols ranked just after analgesics (e.g., codeine pills) and alcohol for drugs that were inappropriately used. This 1983 study did not find any common usage patterns or social class factors. The causes of death for inhalant users in Australia included pneumonia, cardiac failure/arrest, aspiration of vomit, and burns. In 1985, there were 14 communities in Central Australia reporting young people sniffing. In July 1997, it was estimated that there were around 200 young people sniffing petrol across 10 communities in Central Australia. Approximately 40 were classified as chronic sniffers. There have been reports of young Aboriginal people sniffing petrol in the urban areas around Darwin and Alice Springs.

In 2005, the Government of Australia and BP Australia began the usage of opal fuel in remote areas prone to petrol sniffing. Opal is a non-sniffable fuel (which is much less likely to cause a high) and has made a difference in some indigenous communities.

Administration and effects

Inhalant users inhale vapors or aerosol propellant gases using plastic bags held over the mouth or by breathing from an open container of solvents, such as gasoline or paint thinner. Nitrous oxide gases from whipped cream aerosol cans, aerosol hairspray or non-stick frying spray are sprayed into plastic bags. Some nitrous oxide users spray the gas into balloons. When inhaling non-stick cooking spray or other aerosol products, some users may filter the aerosolized particles out with a rag. Some gases, such as propane and butane gases, are inhaled directly from the canister. Once these solvents or gases are inhaled, the extensive capillary surface of the lungs rapidly absorbs the solvent or gas, and blood levels peak rapidly. The intoxication effects occur so quickly that the effects of inhalation can resemble the intensity of effects produced by intravenous injection of other psychoactive drugs.

Ethanol is also inhaled, either by vaporizing it by pouring it over dry ice in a narrow container and inhaling with a straw or by pouring alcohol in a corked bottle with a pipe, and then using a bicycle pump to make a spray. Alcohol can be vaporized using a simple container and open-flame heater. Medical devices such as asthma nebulizers and inhalers were also reported as a means of application. The practice gained popularity in 2004, with the marketing of the device dubbed AWOL (Alcohol without liquid), a play on the military term AWOL (Absent Without Leave). AWOL, created by British businessman Dominic Simler, was first introduced in Asia and Europe, and then in the United States in August 2004. AWOL was used by nightclubs, at gatherings and parties, and it garnered attraction as a novelty, as people 'enjoyed passing it around in a group'. AWOL uses a nebulizer, a machine that agitates the liquid into an aerosol. AWOL's official website states that "AWOL and AWOL 1 are powered by Electrical Air Compressors while AWOL 2 and AWOL 3 are powered by electrical oxygen generators", which refer to a couple of mechanisms used by the nebulizer drug delivery device for inhalation. Although the AWOL machine is marketed as having no downsides, such as the lack of calories or hangovers, Amanda Shaffer of Slate describes these claims as "dubious at best". Although inhaled alcohol does reduce the caloric content, the savings are minimal. After expressed safety and health concerns, sale or use of AWOL machines was banned in a number of American states.

The effects of solvent intoxication can vary widely depending on the dose and what type of solvent or gas is inhaled. A person who has inhaled a small amount of rubber cement or paint thinner vapor may be impaired in a manner resembling alcohol inebriation. A person who has inhaled a larger quantity of solvents or gases, or a stronger chemical, may experience stronger effects such as distortion in perceptions of time and space, hallucinations, and emotional disturbances. The effects of inhalant use are also modified by the combined use of inhalants and alcohol or other drugs.

In the short term, many users experience headaches, nausea and vomiting, slurred speech, loss of motor coordination, and wheezing. A characteristic "glue sniffer's rash" around the nose and mouth is sometimes seen after prolonged use. An odor of paint or solvents on clothes, skin, and breath is sometimes a sign of inhalant abuse, and paint or solvent residues can sometimes emerge in sweat.

According to NIH, even a single session of inhalant use "can disrupt heart rhythms and lower oxygen levels", which can lead to death. "Regular abuse can result in serious harm to the brain, heart, kidneys, and liver."

General risks

Many inhalants are volatile organic chemicals and can catch fire or explode, especially when combined with smoking. As with many other drugs, users may also injure themselves due to loss of coordination or impaired judgment, especially if they attempt to operate machinery.

Hypoxia

All commonly abused inhalants act as asphyxiant gases, although a common myth is that their primary effects are only due to oxygen deprivation. In reality, the majority of abused inhalants still exhibit psychoactive effects, although oxygen deprivation does add to the notable effects.

Regardless of which inhalant is used, inhaling vapors or gases can lead to injury or death. One major risk is hypoxia (lack of oxygen), which can occur due to inhaling fumes from a plastic bag, or from using proper inhalation mask equipment (e.g., a medical mask for nitrous oxide) but not adding oxygen or room air.

Frostbite

Another danger is freezing the throat. When a gas that was stored under high pressure is released, it cools abruptly and can cause frostbite if it is inhaled directly from the container. This can occur, for example, with inhaling nitrous oxide. When nitrous oxide is used as an automotive power adder, its cooling effect is used to make the fuel-air charge denser. In a person, this effect is potentially lethal.

The second cause being especially a risk with heavier-than-air vapors such as butane or gasoline vapor. Deaths typically occur from complications related to excessive sedation and vomiting. Actual overdose from the drug does occur, however, and inhaled solvent use is statistically more likely to result in life-threatening respiratory depression than intravenous use of opioids such as heroin. Most deaths from solvent use could be prevented if individuals were resuscitated quickly when they stopped breathing and their airways cleared if they vomited. However, most inhalant use takes place when people inhale solvents by themselves or in groups of people who are intoxicated. Certain solvents are more hazardous than others, such as gasoline.

Aerosol burn

Use of butane, propane, nitrous oxide and other inhalants can create a risk of freezing burns from contact with the extremely cold liquid. The risk of such contact is greatly increased by the impaired judgement and motor coordination brought on by inhalant intoxication.

Risks of specific agents

Excess NMDA antagonism

Toxicity may also result from the pharmacological properties of the drug; excess NMDA antagonism can completely block calcium influx into neurons and provoke cell death through apoptosis, although this is more likely to be a long-term result of chronic solvent use than a consequence of short-term use.

In popular culture

Music and musical culture

One of the early musical references to inhalant use occurs in the 1974 Elton John song "The Bitch Is Back", in the line "I get high in the evening sniffing pots of glue." Inhalant use, especially glue-sniffing, is widely associated with the late-1970s punk youth subculture in the UK and North America. Raymond Cochrane and Douglas Carroll claim that when glue sniffing became widespread in the late 1970s, it was "adopted by punks because public [negative] perceptions of sniffing fitted in with their self-image" as rebels against societal values. While punks at first used inhalants "experimentally and as a cheap high, adult disgust and hostility [to the practice] encouraged punks to use glue sniffing as a way of shocking society." As well, using inhalants was a way of expressing their anti-corporatist DIY (do it yourself) credo; by using inexpensive household products as inhalants, punks did not have to purchase industrially manufactured liquor or beer.

The punk subculture, in which members may live in squats or on the street, has been associated with "glue sniffing" since its inception.

One history of the punk subculture argues that "substance abuse was often referred to in the music and did become synonymous with the genre, glue-sniffing especially" because the youths' "faith in the future had died and that the youth just didn't care anymore" due to the "awareness of the threat of nuclear war and a pervasive sense of doom." In a BBC interview with a person who was a punk in the late 1970s, they said that "there was a real fear of imminent nuclear war—people were sniffing glue knowing that it could kill them, but they didn't care because they believed that very soon everybody would be dead anyway."

A number of 1970s punk rock and 1980s hardcore punk songs refer to inhalant use. The Ramones, an influential early US punk band, referred to inhalant use in several of their songs. The song "Now I Wanna Sniff Some Glue" describes adolescent boredom, and the song "Carbona not Glue" states, "My brain is stuck from shooting glue." An influential punk fanzine about the subculture and music took its name (Sniffin' Glue) from the Ramones song. The 1980s punk band The Dead Milkmen wrote a song, "Life is Shit" from their album Beelzebubba, about two friends hallucinating after sniffing glue. Punk-band-turned-hip-hop group the Beastie Boys penned a song "Hold it Now – Hit It", which includes the line "cause I'm beer drinkin, breath stinkin, sniffing glue." Their song "Shake Your Rump" includes the lines, "Should I have another sip no skip it/In the back of the ride and bust with the whippits". Pop punk band Sum 41 wrote a song, "Fat Lip", which refers to a character who does not "make sense from all the gas you be huffing..." The song "Lança-Perfume", written and performed by Brazilian pop star Rita Lee, became a national hit in 1980. The song is about chloroethane and its widespread recreational sale and use during the rise of Brazil's carnivals.

Inhalants are referred to by bands from other genres, including several grunge bands—an early 1990s genre that was influenced by punk rock. The 1990s grunge band Nirvana, which was influenced by punk music, penned a song, "Dumb", in which Kurt Cobain sings "my heart is broke / But I have some glue / help me inhale / And mend it with you". L7, an all-female grunge band, penned a song titled "Scrap" about a skinhead who inhales spray-paint fumes until his mind "starts to gel". Also in the 1990s, the Britpop band Suede had a UK hit with their song "Animal Nitrate" whose title is a thinly veiled reference to amyl nitrite. The Beck song "Fume" from his "Fresh Meat and Old Slabs" release is about inhaling nitrous oxide. Another Beck song, "Cold Ass Fashion", contains the line "O.G. – Original Gluesniffer!" Primus's 1999 song "Lacquer Head" is about adolescents who use inhalants to get high. Hip hop performer Eminem wrote a song, "Bad Meets Evil", which refers to breathing "... ether in three lethal amounts." The Brian Jonestown Massacre, a retro-rock band from the 1990s, has a song, "Hyperventilation", which is about sniffing model-airplane cement. Frank Zappa's song "Teenage Wind" from 1981 has a reference to glue sniffing: "Nothing left to do but get out the 'ol glue; Parents, parents; Sniff it good now..."

Films

A number of films have depicted or referred to the use of solvent inhalants. In the 1980 comedy film Airplane!, the character of McCroskey (Lloyd Bridges) refers to his inhalant use when he states, "I picked the wrong week to quit sniffing glue." In the 1996 film Citizen Ruth, the character Ruth (Laura Dern), a homeless drifter, is depicted inhaling patio sealant from a paper bag in an alleyway. In the tragicomedy Love Liza, the main character, played by Philip Seymour Hoffman, plays a man who takes up building remote-controlled airplanes as a hobby to give him an excuse to sniff the fuel in the wake of his wife's suicide.

Harmony Korine's 1997 Gummo depicts adolescent boys inhaling contact cement for a high. Edet Belzberg's 2001 documentary Children Underground chronicles the lives of Romanian street children addicted to inhaling paint. In The Basketball Diaries, a group of boys is huffing Carbona cleaning liquid at 3 minutes and 27 seconds into the movie; further on, a boy is reading a diary describing the experience of sniffing the cleaning liquid.

In the David Lynch film Blue Velvet, the bizarre and manipulative character played by Dennis Hopper uses a mask to inhale amyl nitrite. In Little Shop of Horrors, Steve Martin's character dies from nitrous oxide inhalation. The 1999 independent film Boys Don't Cry depicts two young low-income women inhaling aerosol computer cleaner (compressed gas) for a buzz. In The Cider House Rules, Michael Caine's character is addicted to inhaling ether vapors.

In Thirteen, the main character, a teen, uses a can of aerosol computer cleaner to get high. In the action movie Shooter, an ex-serviceman on the run from the law (Mark Wahlberg) inhales nitrous oxide gas from a number of Whip-It! whipped cream canisters until he becomes unconscious. The South African film The Wooden Camera also depicts the use of inhalants by one of the main characters, a homeless teen, and their use in terms of socio-economic stratification. The title characters in Samson and Delilah sniff petrol; in Samson's case, possibly causing brain damage.

In the 2004 film Taxi, Queen Latifah and Jimmy Fallon are trapped in a room with a burst tank containing nitrous oxide. Queen Latifah's character curses at Fallon while they both laugh hysterically. Fallon's character asks if it is possible to die from nitrous oxide, to which Queen Latifah's character responds with "It's laughing gas, stupid!" Neither of them had any side effects other than their voices becoming much deeper while in the room.

In the French horror film Them (2006), a French couple living in Romania are pursued by a gang of street children who break into their home at night. Olivia Bonamy's character is later tortured and forced to inhale aurolac from a silver-colored bag. During a flashback scene in the 2001 film Hannibal, Hannibal Lecter gets Mason Verger high on amyl nitrite poppers, then convinces Verger to cut off his own face and feed it to his dogs.

Books

The science fiction story "Waterspider" by Philip K. Dick (first published in January 1964 in If magazine) contains a scene in which characters from the future are discussing the culture of the early 1950s. One character says: "You mean he sniffed what they called 'airplane dope'? He was a 'glue-sniffer'?", to which another character replies: "Hardly. That was a mania among adolescents and did not become widespread in fact until a decade later. No, I am speaking about imbibing alcohol."

The book Fear and Loathing in Las Vegas describes how the two main characters inhale diethyl ether and amyl nitrite.

Television

In the comedy series Newman and Baddiel in Pieces, Rob Newman's inhaling gas from a foghorn was a running joke in the series. One episode of the Jeremy Kyle Show featured a woman with a 20-year butane gas addiction. In the series It's Always Sunny in Philadelphia, Charlie Kelly has an addiction to huffing glue. Additionally, season nine episode 8 shows Dennis, Mac, and Dee getting a can of gasoline to use as a solvent, but instead end up taking turns huffing from the canister.

A 2008 episode of the reality show Intervention (season 5, episode 9) featured Allison, who was addicted to huffing computer duster for the short-lived, psychoactive effects. Allison has since achieved a small but significant cult following among bloggers and YouTube users. Several remixes of scenes from Allison's episode can be found online. Since 2009, Allison has worked with drug and alcohol treatment centers in Los Angeles County. In the seventh episode of the fourteenth season of South Park, Towelie, an anthropomorphic towel, develops an addiction to inhaling computer duster. In the show Squidbillies, the main character Early Cuyler is often seen inhaling gas or other substances.

Compressed natural gas

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Compressed_natural_gas

Compressed natural gas (CNG) is a fuel gas mainly composed of methane (CH4), compressed to less than 1% of the volume it occupies at standard atmospheric pressure. It is stored and distributed in hard containers at a pressure of 20–25 megapascals (2,900–3,600 psi), usually in cylindrical or spherical shapes.

CNG is used in traditional petrol/internal combustion engine vehicles that have been modified, or in vehicles specifically manufactured for CNG use: either alone (dedicated), with a segregated liquid fuel system to extend range (dual fuel), or in conjunction with another fuel (bi-fuel). It can be used in place of petrol, diesel fuel, and liquefied petroleum gas (LPG). CNG combustion produces fewer undesirable gases than the aforementioned fuels. In comparison to other fuels, natural gas poses less of a threat in the event of a spill, because it is lighter than air and disperses quickly when released. Biomethane, biogas from anaerobic digestion or landfill, can be used.

In response to high fuel prices and environmental concerns, CNG has been used in auto rickshaws, pickup trucks, transit and school buses, and trains.

The cost and placement of fuel storage containers is the major barrier to wider/quicker adoption of CNG as a fuel. It is also why municipal government, public transportation vehicles were the most visible early adopters of it, as they can more quickly amortize the money invested in the new (and usually cheaper) fuel. In spite of these circumstances, the number of vehicles in the world using CNG has grown steadily (30 percent per year). Now, as a result of the industry's steady growth, the cost of such fuel storage cylinders has been brought down to a much more acceptable level. Especially, for the CNG Type 1 and Type 2 cylinders, many countries are able to make reliable and cost effective cylinders for conversion need.

Energy density

CNG's energy density is the same as liquefied natural gas at 53.6 MJ/kg. Its volumetric energy density, 9 MJ/L, is 42 % of that of LNG (22 MJ/L) because it is not liquefied, and is 25 percent that of diesel fuel.

History

Gases provided the original fuel for internal combustion engines. The first experiments with compressed gases took place in France in the 1850s. Natural gas first became a transport fuel during World War I. In the 1960s, Columbia Natural Gas of Ohio tested a CNG carrier. The ship was to carry compressed natural gas in vertical pressure bottles; however, this design failed because of the high cost of the pressure vessels. Since then, there have been attempts at developing a commercially viable CNG carrier. Several competing CNG ocean transport designs have evolved. Each design proposes a unique approach to optimizing gas transport, while using as much off-the-shelf technology as possible, to keep costs competitive.

Uses

Motor vehicles

CNG pumps at a Brazilian fueling station

Worldwide, there were 14.8 million natural gas vehicles (NGVs) by 2011, with the largest numbers in Iran (4.07 million), Pakistan (2.85 million), Argentina (2.07 million), Brazil (1.7 million) and India (1.1 million), with the Asia-Pacific region leading with 5.7 million NGVs, followed by Latin America with almost four million vehicles.

Several car and vehicle manufacturers, such as Fiat, Opel/General Motors, Peugeot, Volkswagen, Toyota, Honda, Maruti Suzuki, Hyundai, Tata Motors, and others, sell bi-fuel cars. In 2006 Fiat Siena Tetrafuel was introduced in the Brazilian market, equipped with a 1.4-litre FIRE engine that runs on E100, E25 (Standard Brazilian Gasoline), Ethanol, and CNG.

Any existing petrol vehicle can be converted to a dual-fuel petrol/CNG vehicle. Authorized shops can do the retrofitting, which involves installing a CNG cylinder, plumbing, a CNG injection system, and electronics. The cost of installing a CNG conversion kit can often reach $8,000 on passenger cars and light trucks, and is usually reserved for vehicles that travel many miles each year. CNG costs about 50% less than petrol, and emits up to 90% fewer emissions than petrol.

Locomotives

CNG locomotives are operated by several railroads. The Napa Valley Wine Train in the US successfully retrofitted a diesel locomotive to run on compressed natural gas before 2002. This converted locomotive was upgraded to utilize a computer-controlled fuel injection system in May 2008, and is now the Napa Valley Wine Train's primary locomotive. Ferrocarril Central Andino in Peru, has run a CNG locomotive on a freight line since 2005. CNG locomotives are usually diesel–electric locomotives that have been converted to use compressed natural gas generators instead of diesel generators to generate the electricity that drives the traction motors. Some CNG locomotives are able to selectively fire their cylinders only when there is a demand for power, which, theoretically, gives them a higher fuel-efficiency than conventional diesel engines. CNG is also cheaper than petrol or diesel fuel.

Natural gas transport

CNG is used to transport natural gas by sea for intermediate distances, using CNG carrier ships, especially when the infrastructure for pipelines or LNG is not in place. At short distances, undersea pipelines are often more cost-effective, and for longer distances, LNG is often more cost-effective.

Advantages

A CNG-powered bus being refueled in Madrid, Spain.
  • Natural gas vehicles have lower maintenance costs than other hydrocarbon-fuel-powered vehicles.
  • CNG fuel systems are sealed, preventing fuel losses from spills or evaporation.
  • Increased life of lubricating oils, as CNG does not contaminate and dilute the crankcase oil.
  • Being a gaseous fuel, CNG mixes easily and evenly in air.
  • CNG is less likely to ignite on hot surfaces, since it has a high auto-ignition temperature (540 °C), and a narrow range (5–15 percent) of flammability.
  • CNG-powered vehicles are considered to be safer than petrol-powered vehicles.
  • Less pollution and more efficiency:
    • CNG emits significantly less pollution directly than petrol or oil when combusted (e.g., unburned hydrocarbons (UHC), carbon monoxide (CO), nitrogen oxides (NOX), sulfur oxides (SOx) and PM (particulate matter)). For example, an engine running on petrol for 100 km produces 22 kilograms of CO2, while covering the same distance on CNG emits only 16.3 kilograms of CO2.
    • The lifecycle greenhouse gas emissions for CNG compressed from California's pipeline natural gas is given a value of 67.70 grams of CO2-equivalent per megajoule (gCO2e/MJ) by CARB (the California Air Resources Board), approximately 28 percent lower than the average petrol fuel in that market (95.86 gCO2e/MJ).
    • CNG produced from landfill biogas was found by CARB to have the lowest greenhouse gas emissions of any fuel analyzed, with a value of 11.26 gCO2e/MJ (more than 88 percent lower than conventional petrol) in the low-carbon fuel standard that went into effect on January 12, 2010.
    • Due to lower carbon dioxide emissions, switching to CNG can help mitigate greenhouse gas emissions. However, natural gas leaks (both in the direct use and in the production and delivery of the fuel) represent an increase in greenhouse gas emissions. The ability of CNG to reduce greenhouse gas emissions over the entire fuel lifecycle will depend on the source of the natural gas and the fuel it is replacing.

Drawbacks

Compressed natural gas vehicles require a greater amount of space for fuel storage than conventional petrol-powered vehicles. Since it is a compressed gas, rather than a liquid like petrol, CNG takes up more space for each GGE (petrol gallon equivalent). However, the cylinders used to store the CNG take up space in the trunk of a car or bed of a pickup truck that has been modified to additionally run on CNG. This problem is solved in factory-built CNG vehicles that install the cylinders under the body of the vehicle, leaving the trunk free, e.g., Fiat Multipla, New Fiat Panda, Volkswagen Touran Ecofuel, Volkswagen Caddy Ecofuel, Chevy Taxi, which sold in countries such as Peru. Another option is installation on roof (typical on buses), but this could require structural modifications. In 2014, a test (by the Danish Technological Institute) of Euro6 heavy vehicles on CNG and diesel showed that CNG had higher fuel consumption, the same noise and production of CO2 and particulates, but NOX emission was lower.

Leakage of unburned methane as natural gas is a significant issue because methane, the primary component of natural gas, is a powerful, short-lived greenhouse gas. It is more than 100 times more potent at trapping energy than carbon dioxide (CO2), the principal contributor to man-made climate change.

Comparison with other natural gas fuels

Compressed natural gas is often confused with LNG (liquefied natural gas). Both are stored forms of natural gas. The main difference is that CNG is stored at ambient temperature and high pressure, while LNG is stored at low temperature and nearly ambient pressure. In their respective storage conditions, LNG is a liquid and CNG is a supercritical fluid. CNG has a lower cost of production and storage compared to LNG as it does not require an expensive cooling process and cryogenic tanks. However, CNG requires a much larger volume to store the energy equivalent of petrol and the use of very high pressures (3000 to 4000 psi, or 205 to 275 bar). As a consequence of this, LNG is often used for transporting natural gas over large distances, in ships, trains or pipelines, where the gas is converted into CNG before distribution to the end user.

Natural gas is being experimentally stored at lower pressure in a form known as an ANG (adsorbed natural gas) cylinder, where it is adsorbed at 35 bar (500 psi, the pressure of gas in natural gas pipelines) in various sponge-like materials, such as carbon and MOFs (metal-organic frameworks). The fuel is stored at similar or greater energy density than CNG. This means that vehicles can be refueled from the natural gas network without extra gas compression, the fuel cylinders can be slimmed down and made of lighter, weaker materials.

It is possible to mix the ANG and CNG technology to reach an increased capacity of natural gas storage. In this process known as high pressure ANG, a high pressure CNG tank is filled by absorbers such as activated carbon (which is an adsorbent with high surface area) and stores natural gas by both CNG and ANG mechanisms.

Compressed natural gas is sometimes mixed with hydrogen (HCNG), which increases the H/C ratio (hydrogen/carbon ratio) of the fuel and gives it a flame speed up to eight times higher than CNG.

Codes and standards

The lack of harmonized codes and standards across international jurisdictions is an additional barrier to NGV market penetration. The International Organization for Standardization has an active technical committee working on a standard for natural gas fuelling stations for vehicles.

Despite the lack of harmonized international codes, natural gas vehicles have an excellent global safety record. Existing international standards include ISO 14469-2:2007 which applies to CNG vehicle nozzles and receptacle and ISO 15500-9:2012 specifies tests and requirements for the pressure regulator.

The National Fire Protection Association's NFPA 52 code covers natural gas vehicle safety standards in the United States.

Worldwide adoption

Top ten countries
with the largest NGV vehicle fleets – 2013

(millions)
Rank Country Registered
fleet
Rank Country Registered
fleet
1  Iran 3.50 6  Italy 0.82
2  Pakistan 2.79 7  Colombia 0.46
3  Argentina 2.28 8  Uzbekistan 0.45
4  Brazil 1.75 9  Thailand 0.42
5  China 1.58 10  Indonesia 0.38
World Total = 18.09 million NGV vehicles

Iran, Pakistan, Argentina, Brazil and China have the highest number of CNG run vehicles in the world.

Natural gas vehicles are increasingly used in Iran, Pakistan, the Asia-Pacific region, the Indian capital of Delhi, and other large cities such as Ahmedabad, Mumbai, Pune, and Kolkata, as well as cities such as Lucknow, Kanpur, Varanasi, and others.

Its use is also increasing in South America, Europe, and North America, because of rising petrol prices.

Africa

Egypt is amongst the top 10 countries in CNG adoption, with 128,754 CNG vehicles and 124 CNG fueling stations. Egypt was also the first nation in Africa and the Middle East to open a public CNG fueling station in January 1996.

The vast majority (780,000) have been produced as dual fuel-vehicles by the auto manufacturer in the last two years, and the remainder have been converted utilizing after market conversion kits in workshops. There are 750 active refueling stations country wide with an additional 660 refueling stations under construction and expected to come on stream. Currently the major problem facing the industry as a whole is the building of refueling stations that is lagging behind dual fuel vehicle production, forcing many to use petrol instead.

Nigeria CNG started with a pilot project in Benin City Edo State in 2010 by NIPCO Gas Limited. NIPCO Gas Limited is a 100% subsidiary of NIPCO PLC. As of June 2020, seven CNG stations have been built in Benin City Edo State, with about 7,500 cars running on CNG in Benin City Edo state. In Benin City Edo state, major companies such as Coca-Cola, 7up, Yongxing Steel are using CNG to power their fork-lifts/trucks while Edo City Transport Ltd (ECTS) is also running some of its buses on CNG. Kwale, Nigeria CNG stations were inaugurated by Mr. Abhishek Sharma, the head of marketing (Natural Gas) from NIPCO Gas Limited in 2019.

Asia

A CNG powered Hino bus, operated by BMTA in Thailand.

China

A CNG powered bus in Beijing. CNG buses in Beijing were introduced in late 1998.

In China, companies such as Sino-Energy are active in expanding the footprint of CNG filling stations in medium-size cities across the interior of the country, where at least two natural gas pipelines are operational.

Malaysia

In Malaysia, the use of CNG was originally introduced for taxicabs and airport limousines during the late 1990s, when new taxis were launched with CNG engines while taxicab operators were encouraged to send in existing taxis for full engine conversions. The practice of using CNG remained largely confined to taxicabs predominately in the Klang Valley and Penang due to a lack of interest. No incentives were offered for those besides taxicab owners to use CNG engines, while government subsidies on petrol and diesel made conventional road vehicles cheaper to use in the eyes of the consumers. Petronas, Malaysia's state-owned oil company, also monopolises the provision of CNG to road users. As of July 2008, Petronas only operates about 150 CNG refueling stations, most of which are concentrated in the Klang Valley. At the same time, another 50 were expected by the end of 2008.

As fuel subsidies were gradually removed in Malaysia starting June 5, 2008, the subsequent 41 percent price hike on petrol and diesel fuel led to a 500 percent increase in the number of new CNG cylinders installed. National car maker Proton considered fitting its Waja, Saga and Persona models with CNG kits from Prins Autogassystemen by the end of 2008, while a local distributor of locally assembled Hyundai cars offers new models with CNG kits.[35] Conversion centres, which also benefited from the rush for lower running costs, also perform partial conversions to existing road vehicles, allowing them to run on both petrol or diesel and CNG with a cost varying between RM3,500 to RM5,000 for passenger cars.

Myanmar

The Ministry of Transport of Myanmar passed a law in 2005 which required that all public transport vehicles – buses, trucks and taxis, be converted to run on CNG. The Government permitted several private companies to handle the conversion of existing diesel and petrol cars, and also to begin importing CNG variants of buses and taxis. Accidents and rumours of accidents, partly fueled by Myanmar's position in local hydrocarbon politics, has discouraged citizens from using CNG vehicles, although now almost every taxi and public bus in Yangon, Myanmar's largest city, run on CNG. CNG stations have been set up around Yangon and other cities, but electricity shortages mean that vehicles may have to queue up for hours to fill their gas containers. The Burmese opposition movements are against the conversion to CNG, as they accuse the companies of being proxies of the junta, and also their desire that the petrodollars earned by the regime should go towards the defense sector rather than towards improving the infrastructure or welfare of the people.

India

In India, there are over 4500 CNG Stations all over the country now as compared to 2014 when the country only had about 900 CNG Stations. The government is aiming to increase the use of CNG powered vehicles by setting up more CNG stations in the country, the aim is to increase the current number to 8000 CNG Stations in the next two years.

As of December 2022, the state of Gujarat has the highest number of CNG Pumps in the country followed by Uttar Pradesh being the second highest and with Maharashtra falling little behind the above regions.

Pakistan

In Pakistan, the Karachi government under the order of the Supreme Court in 2004 made it mandatory for all city buses and auto rickshaws to run on CNG with the intention of reducing air pollution.

In 2012, the federal government announced plans to gradually phase out CNG over a period of approximately three years given natural gas shortages which have been negatively affecting the manufacturing sector. Aside from limiting electricity generation capacity, gas shortages in Pakistan have also raised the costs of business for key industries including the fertilizer, cement and textile sectors.

Singapore

A retired CNG powered Volvo B10BLE bus, operated by SBS Transit in Singapore.

In Singapore, CNG was once used by public transport vehicles like buses and taxis, as well as goods vehicles until 2018. During its heyday in 2008 onwards, more owners of private cars had sought interest in converting their petrol-driven vehicles to also run on CNG – due to rising petrol prices. The initial cost of converting a regular vehicle to dual fuel at the German conversion workshop of C. Melchers, for example, is around S$3,800; with the promise of real cost-savings that dual-fuel vehicles bring over the long term.

Singapore currently has five operating filling stations for natural gas. Sembcorp Gas Pte Ltd. runs the station on Jurong Island and, jointly with Singapore Petroleum Company, the filling station at Jalan Buroh. Both these stations are in the western part of the country. Another station on the mainland is in Mandai Link to the north and is operated by SMART Energy. SMART also own a second station on Serangoon North Ave 5 which was set up end of March 2009; The fifth and largest station in the world, located in Toh Tuck, was opened by the UNION Group in September 2009. This station is recognized by the Guniness World Records as being the largest in the world with 46 refuelling hoses. The Union Group, which operates 1000 CNG Toyota Wish taxis then planned to introduce another three daughter stations and increase the CNG taxi fleet to 8000 units.

As a key incentive for using this eco-friendly fuel Singapore has a green vehicle rebate for users of CNG technology. First introduced in January 2001, the GVR grants a 40 percent discount on the OMV (open market value) cost of newly registered green passenger vehicles. This initiative will end at the end of 2012 as the government believes the 'critical mass' of CNG vehicles would then have been built up.

Due to reliability issues and lower ranges that CNG provided (as cited by users’ feedback), refueling stations mostly concentrated in the western end of Singapore, the rising demand of greener solutions like hybrid technologies, led to its demise where both public buses and the last CNG taxis were on its way to being scrapped in 2018.

Europe

CNG powered bus in Italy

In Italy, there are more than 1173 CNG stations. The use of methane for vehicles, started in the 1930s and has continued off and on until today. Since 2008 there have been a large market expansion for natural gas vehicles (CNG and LPG) caused by the rise of petrol prices and by the need to reduce air pollution emissions. Before 1995 the only way to have a CNG-powered car was by having it retrofitted with an after-market kit. A large producer was Landi Renzo, Tartarini Auto, Prins Autogassystemen, OMVL, BiGAs,... and AeB for electronic parts used by the most part of kit producer. Landi Renzo and Tartarini selling vehicles in Asia and South America. After 1995 bi-fuel cars (petrol/CNG) became available from several major manufacturers. Currently Fiat, Opel, Volkswagen, Citroën, Renault, Volvo and Mercedes sell various car models and small trucks that are petrol/CNG powered. Usually CNG parts used by major car manufacturers are actually produced by automotive aftermarket kit manufacturers, e.g. Fiat use Tartarini Auto components, Volkswagen use Teleflex GFI and Landi Renzo components.

In Belgium, CNG is a very new fuel. At the beginning of 2014 there were only 17 refuelling stations, all of them in Flanders, but the number is now increasing rapidly. At the beginning of 2015 there were 29 refueling stations in Belgium, all of them in Flanders. As of January 2017, there are 76 active refueling stations in Belgium, most of them being in Flanders since only 7 of them are in Wallonia or Brussels. As a fuel and compared to petrol, CNG has an advantageous fiscal treatment with lower excises duties (although VAT is always paid). Since CNG, as a car fuel, is not totally exempted of excise duties, CNG cars do not pay a prime road tax to partially compensate the State for the loss of revenue. Instead LPG cars pay a prime road tax in Belgium, because LPG is totally exempted from excise duties. Since CNG is not totally exempted of excise duties, in Belgium it is allowed to connect a car to the home network of natural gas and to refuel the car from home. The purchase of CNG cars is not subsidised by the government, but by the Belgian producers and distributors of natural gas. Fiat and Volkswagen sell factory-equipped CNG-cars in Belgium. At the end of 2018 there were 11,188 vehicles running with CNG in Belgium.

CNG powered bus in Germany

In Germany, CNG-generated vehicles are expected to increase to two million units of motor-transport by 2020. The cost for CNG fuel is between 1/3 and 1/2 compared to other fossil fuels in Europe. In 2016 there are around 900 CNG stations in Germany and major German car manufacturers like Volkswagen, Mercedes, Opel, Audi offer CNG engines on most of their models. Augsburg is one of the few cities that only run CNG operated public buses since 2011.

In Turkey, Ankara municipality is increasingly using CNG buses, where numbers have reached 1090 by 2011. Istanbul has started in 2014 with an order of 110 buses. Konya also added 60 buses to its fleet the same year.

In Portugal, there are 9 CNG refueling stations as of September 25, 2017.

In Hungary, there are four public CNG refueling stations in the cities Budapest, Szeged, Pécs and Győr. The public transportation company of Szeged, Szolnok and some districts in Budapest runs buses mainly on CNG.

In Bulgaria, there are 96 CNG refueling stations as of July 2011. One can be found in most of Bulgaria's big towns. In the capital Sofia there are 22 CNG stations making it possibly the city with the most publicly available CNG stations in Europe. There are also quite a few in Plovdiv, Ruse, Stara Zagora and Veliko Tarnovo as well as in the towns on the Black Sea – Varna, Burgas, Nesebar and Kavarna. CNG vehicles are becoming more and more popular in the country. The fuel is mostly used by taxi drivers because of its much lower price compared to petrol. Currently (as of July, 2015) the city of Sofia is rapidly renewing its public transport fleet with MAN Lion's City buses running on CNG. Also, many companies switch to CNG cargo vans and even heavy trucks for their daily operations within city limits.

In North Macedonia, there is one CNG station located in the capital Skopje, but it is not for public use. Only twenty buses of the local Public Transport Company have been fitted to use a mixture of diesel and CNG. The first commercial CNG station in Skopje is in the advanced stage of development and was expected to start operation in July 2011.

In Serbia, there are about 20 public CNG refuelling stations as of August 2019. Four in the capital Belgrade, and the rest in the towns of Subotica (1), Novi Sad (1), Zrenjanin (1), Pancevo (2), Kruševac (1), Kragujevac (1), Cacak (2), and so on. Detailed list is currently available on CNGEurope Web site. 

In Slovenia, there are four public CNG refuelling stations as of December 2018. Two in the capital Ljubljana, and one each in Maribor and Jesenice. Additionally, at least 14 new refuelling stations are planned in all city municipalities by the end of 2020. Ljubljana Passenger Transport operates 66 CNG fuelled city buses, as of May 2016. Its Maribor counterpart, Marprom has 19 CNG city buses in their fleet, as of October 2018.

In Croatia, there are two public CNG refuelling stations situated close to the center of Zagreb and in Rijeka. At least 60 CNG buses are in use as a form of a public transport (Zagreb public transport services).

In Estonia, there are 11 public CNG refuelling stations – four in the country's capital Tallinn, and one each in Tartu, Pärnu, Viljandi, Rakvere, Jõhvi, and Narva. From 2011 on, Tartu has five Scania-manufactured CNG buses operating its inner-city routes.

CNG powered bus in Sweden

In Sweden, there are currently 90 CNG filling stations available to the public (as compared to about 10 LPG filling stations), primarily located in the southern and western parts of the country as well the Mälardalen region Another 70–80 CNG filling stations are under construction or in a late stage of planning (completions 2009–2010). Several of the planned filling stations are located in the northern parts of the country, which will greatly improve the infrastructure for CNG car users. There are approx. 14,500 CNG vehicles in Sweden (2007), of which approx. 13,500 are passenger cars and the remainder includes buses and trucks. In Stockholm, the public transportation company SL currently operates 50 CNG buses but have a capacity to operate 500. The Swedish government recently prolonged its subsidies for the development of CNG filling stations, from 2009 to 2012–31 to 2010-12-31.

In Spain, CNG is a very new fuel and the refueling network is being developed. In Madrid, the EMT, uses 1915 buses running with CNG. At the beginning of 2015 there were 35 CNG refueling stations in Spain. Several car brands sell brand-new cars running with CNG, including Fiat, Volkswagen, Seat and Skoda among others.

As of 2013, there are 47 public CNG filling stations in the Czech Republic, mainly in the big cities. Local bus manufacturers SOR Libchavy and Tedom produce CNG versions of their vehicles, with roof-mounted cylinders.

Middle East

Iran

Iran has one of the largest fleets of CNG vehicles and CNG distribution networks in the world. There are 2335 CNG fueling stations, with a total of 13,534 CNG nozzles. The number of CNG burning vehicles in Iran exceeds 3.5 million. CNG consumption by Iran's transportation sector is around 20 million cubic meters per day.

North America

The Honda Civic GX is factory-built to run on CNG and it is available in several U.S. regional markets.
Buses powered with CNG are common in the United States such as the New Flyer Industries C40LF bus in Washington, D.C. shown here.

Canada

Natural gas has been used as a motor fuel in Canada for over 20 years. With assistance from federal and provincial research programs, demonstration projects and NGV market deployment programs during the 1980s and 1990s, the population of light-duty NGVs grew to over 35,000 by the early 1990s. This assistance resulted in a significant adoption of natural gas transit buses as well.

The NGV market started to decline after 1995, eventually reaching today's vehicle population of about 12,000.

This figure includes 150 urban transit buses, 45 school buses, 9,450 light-duty cars and trucks, and 2,400 forklifts and ice-resurfacers. The total fuel use in all NGV markets in Canada was 1.9 PJs (petajoules) in 2007 (or 54.6 million liters of petrol liters equivalent), down from 2.6 PJs in 1997. Public CNG refueling stations have declined in quantity from 134 in 1997 to 72 today. There are 22 in British Columbia, 12 in Alberta, 10 in Saskatchewan, 27 in Ontario and two in Québec. There are only 12 private fleet stations.

Canadian industry has developed CNG-fueled truck and bus engines, CNG-fueled transit buses, and light trucks and taxis.

Fuelmaker Corporation of Toronto, the Honda-owned manufacturer of CNG auto refueling units, was forced into bankruptcy by parent Honda USA for an unspecified reason in 2009. The various assets of Fuelmaker were subsequently acquired by Fuel Systems Corporation of Santa Ana, California.

United States

This MARTA Bus is a New Flyer XN40 which runs on CNG. 70% of MARTA's bus fleet is CNG.
CNG Fueling Station in Columbus, Ohio

Similar to Canada, the United States has implemented various NGV initiatives and programs since 1980, but has had limited success in sustaining the market. There were 105,000 NGVs in operation in 2000; this figure peaked at 121,000 in 2004, and decreased to 110,000 in 2009.

In the United States, federal tax credits are available for buying a new CNG vehicle. Use of CNG varies from state to state; only 34 states have at least one CNG fueling site.

In Texas, Railroad Commissioner David Porter launched his Texas Natural Gas Initiative in October 2013 to encourage the adoption of natural gas fuel in the transportation and exploration and production sectors. As of 2015 Texas is rapidly becoming a leader in natural gas infrastructure in the US with 137 natural gas fueling stations (private and public). Nine months into FY2015 Commissioner Porter reports Texas CNG, LNG Sales Show 78 Percent Increase Over FY 2014 year to date. Per Commissioner Porter in June 2015: "Natural gas vehicles are becoming mainstream faster than expected. These collections are nearly double the amount collected last year at this time. At 15 cents per gallon equivalent, $3,033,600 of motor fuel tax equates to the sale of 20,224,000 gallon equivalents of natural gas." The $3 million in Texas natural gas tax receipts is for both CNG and LNG for FY2015 through the May 2015. The Texas fiscal year starts Sept 1 so 9 months tax collections are represented.

In Athens, Ala., the city and its Gas Department installed a public CNG station on the Interstate 65 Corridor, making it the only public CNG station between Birmingham and Nashville as of February 2014. The city's larger fleet vehicles such as garbage trucks also use this public station for fueling. The city also has two slow-fill non-public CNG stations for its fleet. Athens has added CNG/petrol Tahoes for police and fire, a CNG Honda Civic, CNG Heil garbage trucks, and CNG/petrol Dodge pickup trucks to its fleet.

In California, CNG is used extensively in local city and county fleets, as well as public transportation (city/school buses). There are 90 public fueling stations in southern California alone, and travel from San Diego so the Bay Area to Las Vegas and Utah is routine with the advent of online station maps such as www.cngprices.com. Compressed natural gas is typically available for 30-60 percent less than the cost of petrol in much of California.

Gwinnett County Transit Orion VII CNG 029 on the 35 Bus on Peachtree Corners.

The 28 buses running the Gwinnett County Transit local routes run on 100 percent CNG. Additionally, about half of the Georgia Regional Transportation Authority express fleet, which runs and refuels out of the Gwinnett County Transit facility, uses CNG.

The Massachusetts Bay Transportation Authority was running 360 CNG buses as early as in 2007, and is the largest user in the state.

The Metropolitan Transportation Authority (MTA) of New York City currently has over 900 buses powered by compressed natural gas, with CNG bus depots located in Brooklyn, The Bronx, and Queens.

The Nassau Inter-County Express (or NICE Bus, formerly New York MTA Long Island Bus) runs a 100% Orion CNG-fueled bus fleet for fixed-route service, consisting of 360 buses for service in Nassau County, parts of Queens, New York, and the western sections of Suffolk County.

The City of Harrisburg, Arkansas has switched some of the city's vehicles to compressed natural gas in an effort to save money on fuel costs. Trucks used by the city's street and water, sewer, and gas departments have been converted from petrol to CNG.

Personal use of CNG is currently a small niche market, though with current tax incentives and a growing number of public fueling stations available, it is experiencing unprecedented growth. The state of Utah offers a subsidised statewide network of CNG filling stations at a rate of $1.57/gge, while petrol is above $4.00/gal.

Elsewhere in the nation, retail prices average around $2.50/gge, with home refueling units compressing gas from residential gas lines for under $1/gge. Other than aftermarket conversions, and government used vehicle auctions, the only currently produced CNG vehicle in the United States is the Honda Civic GX sedan, which is made in limited numbers and available only in states with retail fueling outlets.

An initiative, known as Pickens Plan, calls for the expansion of the use of CNG as a standard fuel for heavy vehicles has been recently started by oilman and entrepreneur T. Boone Pickens. California voters defeated Proposition 10 in the 2008 General Election by a significant (59.8 percent to 40.2 percent) margin. Proposition 10 was a $5 billion bond measure that, among other things, would have given rebates to state residents that purchase CNG vehicles.

On February 21, 2013, T. Boone Pickens and New York Mayor, Michael Bloomberg unveiled a CNG powered mobile pizzeria. The company, Neapolitan Express uses alternative energy to run the truck as well as 100 percent recycled and compostable materials for their carryout boxes.

Congress has encouraged conversion of cars to CNG with a tax credits of up to 50 percent of the auto conversion cost and the CNG home filling station cost. However, while CNG is much cleaner fuel, the conversion requires a type certificate from the EPA. Meeting the requirements of a type certificate can cost up to $50,000. Other non-EPA approved kits are available. A complete and safe aftermarket conversion using a non-EPA approved kit can be achieved for as little as $400 without the cylinder.

Deployments

AT&T ordered 1,200 CNG-powered cargo vans from General Motors in 2012. It is the largest-ever order of CNG vehicles from General Motors to date. AT&T has announced its intention to invest up to $565 million to deploy approximately 15,000 alternative fuel vehicles over a 10-year period through 2018, will use the vans to provide and maintain communications, high-speed Internet and television services for AT&T customers.

South America

CNG station in Rosario, Argentina.

CNG vehicles are commonly used in South America, where these vehicles are mainly used as taxicabs in main cities of Argentina and Brazil. Normally, standard petrol vehicles are retrofitted in specialized shops, which involve installing the gas cylinder in the trunk and the CNG injection system and electronics. Argentina and Brazil are the two countries with the largest fleets of CNG vehicles, with a combined total fleet of more than 3.4 million vehicles by 2009. Conversion has been facilitated by a substantial price differential with liquid fuels, locally produced conversion equipment and a growing CNG-delivery infrastructure.

As of 2009 Argentina had 1,807,186 NGV's with 1,851 refueling stations across the nation, or 15 percent of all vehicles; and Brazil had 1,632,101 vehicles and 1,704 refueling stations, with a higher concentration in the cities of Rio de Janeiro and São Paulo.

Colombia had an NGV fleet of 300,000 vehicles, and 460 refueling stations, as of 2009. Bolivia has increased its fleet from 10,000 in 2003 to 121,908 units in 2009, with 128 refueling stations. Peru had 81,024 NGVs and 94 fueling stations as 2009, but that number is expected to skyrocket as Peru sits on South America's largest gas reserves. In Peru several factory-built NGVs have the cylinders installed under the body of the vehicle, leaving the trunk free. Among the models built with this feature are the Fiat Multipla, the new Fiat Panda, the Volkswagen Touran Ecofuel, the Volkswagen Caddy Ecofuel and the Chevy Taxi. Other countries with significant NGV fleets are Venezuela (15,000) and Chile (8,064) as of 2009.

Oceania

During the 1970s and 1980s, CNG was commonly used in New Zealand in the wake of the oil crises, but fell into decline after petrol prices receded. At the peak of natural gas use, 10 percent of New Zealand's cars were converted, around 110,000 vehicles.

A Custom Coaches bodied Mercedes-Benz O405NH running on CNG, operated by Sydney Buses in Australia
Transperth Mercedes-Benz OC500LE running on CNG

For a period of time, Brisbane Transport in Queensland, Australia adopted a policy of purchasing only CNG buses. Brisbane Transport has 215 Scania L94UB and 324 MAN 18.310 models as well as 30 MAN NG 313 articulated CNG buses. The State Transit Authority purchased 100 Scania L113CRB, 283 Mercedes-Benz O405NH and 254 Euro 5-compliant Mercedes-Benz OC500LE buses.

In the 1990s, Benders Busways of Geelong, Victoria trialled CNG buses for the Energy Research and Development Corporation.

Martin Ferguson, Ollie Clark and Noel Childs featured on The 7:30 Report raised the issue of CNG as an overlooked transport fuel option in Australia, highlighting the large volumes of LNG currently being exported from the North West Shelf in light of the cost of importing crude oil to Australia.

Emerging technologies

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