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Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or nos, is a
chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
, an oxide of nitrogen with the formula . At room temperature, it is a colourless
non-flammable A combustible material is something that can burn (i.e., ''combust'') in air. A combustible material is flammable if it ignites easily at ambient temperatures. In other words, a combustible material ignites with some effort and a flammable mat ...
gas Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...
, and has a slightly sweet scent and taste. At elevated temperatures, nitrous oxide is a powerful
oxidiser An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxi ...
similar to molecular oxygen. Nitrous oxide has significant medical uses, especially in
surgery Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pat ...
and
dentistry Dentistry, also known as dental medicine and oral medicine, is the branch of medicine focused on the teeth, gums, and mouth. It consists of the study, diagnosis, prevention, management, and treatment of diseases, disorders, and conditions o ...
, for its
anaesthetic An anesthetic (American English) or anaesthetic (British English; see spelling differences) is a drug used to induce anesthesia ⁠— ⁠in other words, to result in a temporary loss of sensation or awareness. They may be divided into two ...
and pain-reducing effects. Its colloquial name, "laughing gas", coined by
Humphry Davy Sir Humphry Davy, 1st Baronet, (17 December 177829 May 1829) was a British chemist and inventor who invented the Davy lamp and a very early form of arc lamp. He is also remembered for isolating, by using electricity, several elements for t ...
, is due to the
euphoric Euphoria ( ) is the experience (or affect) of pleasure or excitement and intense feelings of well-being and happiness. Certain natural rewards and social activities, such as aerobic exercise, laughter, listening to or making music and da ...
effects upon inhaling it, a property that has led to its
recreational use Recreational drug use indicates the use of one or more psychoactive drugs to induce an altered state of consciousness either for pleasure or for some other casual purpose or pastime by modifying the perceptions and emotions of the user. When a ...
as a
dissociative Dissociatives, colloquially dissos, are a subclass of hallucinogens which distort perception of sight and sound and produce feelings of detachment – dissociation – from the environment and/or self. Although many kinds of drugs are capable of ...
anaesthetic. It is on the
World Health Organization's List of Essential Medicines The WHO Model List of Essential Medicines (aka Essential Medicines List or EML), published by the World Health Organization (WHO), contains the medications considered to be most effective and safe to meet the most important needs in a health s ...
. It is also used as an oxidiser in
rocket propellant Rocket propellant is the reaction mass of a rocket. This reaction mass is ejected at the highest achievable velocity from a rocket engine A rocket engine uses stored rocket propellants as the reaction mass for forming a high-speed propuls ...
s, and in
motor racing Motorsport, motorsports or motor sport is a global term used to encompass the group of competitive sporting events which primarily involve the use of motorized vehicles. The terminology can also be used to describe forms of competition of tw ...
to increase the
power output Power most often refers to: * Power (physics), meaning "rate of doing work" ** Engine power, the power put out by an engine ** Electric power * Power (social and political), the ability to influence people or events ** Abusive power Power may ...
of
engines An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power g ...
. Nitrous oxide's atmospheric concentration reached 333 
parts per billion In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they ...
(ppb) in 2020, increasing at a rate of about 1 ppb annually. It is a major scavenger of
stratospheric ozone The ozone layer or ozone shield is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet radiation. It contains a high concentration of ozone (O3) in relation to other parts of the atmosphere, although still small in relat ...
, with an impact comparable to that of
CFCs Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are fully or partly halogenated hydrocarbons that contain carbon (C), hydrogen (H), chlorine (Cl), and fluorine (F), produced as volatile derivatives of methane, ethane, and propan ...
. Global accounting of sources and sinks over the decade ending 2016 indicates that about 40% of the average 17 TgN/yr (
teragram The kilogram (also kilogramme) is the unit of mass in the International System of Units (SI), having the unit symbol kg. It is a widely used measure in science, engineering and commerce worldwide, and is often simply called a kilo colloquially. ...
s of nitrogen per year) of emissions originated from human activity, and shows that emissions growth chiefly came from expanding
agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to ...
and industry sources within emerging economies. Being the third most important long-lived
greenhouse gas A greenhouse gas (GHG or GhG) is a gas that Absorption (electromagnetic radiation), absorbs and Emission (electromagnetic radiation), emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse ...
, nitrous oxide also substantially contributes to
global warming In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
. Nitrous oxide is used as a propellant, and has a variety of applications from
rocketry Rocketry may refer to: Science and technology * The design and construction of rockets ** The hobbyist or (semi-)professional use of model rockets * Aerospace engineering, also known as rocket science * Amateur rocketry, a hobby in which parti ...
to making whipped cream. It is used as a recreational drug for its potential to induce a brief "high"; most recreational users are unaware of its
neurotoxicity Neurotoxicity is a form of toxicity in which a biological, chemical, or physical agent produces an adverse effect on the structure or function of the central and/or peripheral nervous system. It occurs when exposure to a substance – specificall ...
and potential to cause neurological damage.


Uses


Rocket motors

Nitrous oxide may be used as an
oxidiser An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxi ...
in a
rocket A rocket (from it, rocchetto, , bobbin/spool) is a vehicle that uses jet propulsion to accelerate without using the surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Rocket engines work entirely fr ...
motor. It has advantages over other oxidisers in that it is much less toxic, and because of its stability at room temperature it is also easier to store and relatively safe to carry on a flight. As a secondary benefit, it may be decomposed readily to form breathing air. Its high density and low storage pressure (when maintained at low temperature) enable it to be highly competitive with stored high-pressure gas systems. In a 1914 patent, American rocket pioneer
Robert Goddard Robert Hutchings Goddard (October 5, 1882 – August 10, 1945) was an American engineer, professor, physicist, and inventor who is credited with creating and building the world's first liquid-fueled rocket. Goddard successfully laun ...
suggested nitrous oxide and gasoline as possible propellants for a liquid-fuelled rocket. Nitrous oxide has been the oxidiser of choice in several
hybrid rocket A hybrid-propellant rocket is a rocket with a rocket motor that uses rocket propellants in two different phases: one solid and the other either gas or liquid. The hybrid rocket concept can be traced back to the early 1930s. Hybrid rockets avo ...
designs (using solid fuel with a liquid or gaseous oxidiser). The combination of nitrous oxide with hydroxyl-terminated polybutadiene fuel has been used by
SpaceShipOne SpaceShipOne is an experimental air-launched rocket-powered aircraft with sub-orbital spaceflight capability at speeds of up to 3,000 ft/s (900 m/s, 3240 km/h), using a hybrid rocket motor. The design features a unique " feathering ...
and others. It also is notably used in
amateur An amateur () is generally considered a person who pursues an avocation independent from their source of income. Amateurs and their pursuits are also described as popular, informal, autodidacticism, self-taught, user-generated, do it yourself, DI ...
and high power rocketry with various plastics as the fuel. Nitrous oxide also may be used in a
monopropellant rocket A monopropellant rocket (or "monochemical rocket") is a rocket that uses a single chemical as its propellant. Chemical-reaction monopropellant rockets For monopropellant rockets that depend on a chemical reaction, the power for the propulsive re ...
. In the presence of a heated
catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
, will decompose exothermically into nitrogen and oxygen, at a temperature of approximately . Because of the large heat release, the catalytic action rapidly becomes secondary, as thermal autodecomposition becomes dominant. In a vacuum thruster, this may provide a monopropellant
specific impulse Specific impulse (usually abbreviated ) is a measure of how efficiently a reaction mass engine (a rocket using propellant or a jet engine using fuel) creates thrust. For engines whose reaction mass is only the fuel they carry, specific impulse i ...
(''I'') of as much as 180 s. While noticeably less than the ''I'' available from
hydrazine Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazine ...
thrusters (monopropellant or
bipropellant The highest specific impulse chemical rockets use liquid propellants (liquid-propellant rockets). They can consist of a single chemical (a monopropellant) or a mix of two chemicals, called bipropellants. Bipropellants can further be divided into ...
with dinitrogen tetroxide), the decreased toxicity makes nitrous oxide an option worth investigating. Nitrous oxide is said to
deflagrate Deflagration (Lat: ''de + flagrare'', "to burn down") is subsonic combustion in which a pre-mixed flame propagates through a mixture of fuel and oxidizer. Deflagrations can only occur in pre-mixed fuels. Most fires found in daily life are diffu ...
at approximately at a pressure of 309 psi (21 atmospheres).Munke, Konrad (2 July 2001
Nitrous Oxide Trailer Rupture
Report at CGA Seminar "Safety and Reliability of Industrial Gases, Equipment and Facilities", 15–17 October 2001, St. Louis, Missouri
At 600 , for example, the required ignition energy is only 6 joules, whereas at 130 psi a 2,500-joule ignition energy input is insufficient.


Internal combustion engine

In vehicle
racing In sport, racing is a competition of speed, in which competitors try to complete a given task in the shortest amount of time. Typically this involves traversing some distance, but it can be any other task involving speed to reach a specific goa ...
, nitrous oxide (often referred to as just "
nitrous A Nitrous Oxide Engine, or Nitrous Oxide System commonly referred to and known as NOS, is an internal combustion engine in which oxygen for burning the fuel comes from the decomposition of nitrous oxide, N2O, rather than air. The system incre ...
") allows the engine to burn more fuel by providing more oxygen during combustion. The increase in oxygen allows for an increase in the injection of fuel, allowing the engine to produce more
engine power Engine power is the power that an engine can put out. It can be expressed in power units, most commonly kilowatt, pferdestärke (metric horsepower), or horsepower. In terms of internal combustion engines, the engine power usually describes the ' ...
. The gas is not flammable at a low pressure/temperature, but it delivers more oxygen than atmospheric air by breaking down at elevated temperatures, about 570 degrees F (~300C). Therefore, it often is mixed with another fuel that is easier to deflagrate. Nitrous oxide is a strong oxidising agent, roughly equivalent to hydrogen peroxide, and much stronger than oxygen gas. Nitrous oxide is stored as a compressed liquid; the
evaporation Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...
and expansion of liquid nitrous oxide in the
intake manifold In automotive engineering, an inlet manifold or intake manifold (in American English) is the part of an engine that supplies the fuel/ air mixture to the cylinders. The word ''manifold'' comes from the Old English word ''manigfeald'' (from the ...
causes a large drop in intake charge temperature, resulting in a denser charge, further allowing more air/fuel mixture to enter the cylinder. Sometimes nitrous oxide is injected into (or prior to) the intake manifold, whereas other systems directly inject, right before the cylinder (direct port injection) to increase power. The technique was used during
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
by
Luftwaffe The ''Luftwaffe'' () was the aerial-warfare branch of the German ''Wehrmacht'' before and during World War II. Germany's military air arms during World War I, the ''Luftstreitkräfte'' of the Imperial Army and the '' Marine-Fliegerabtei ...
aircraft with the
GM-1 {{unreferenced, date=September 2008 GM-1 (''Göring Mischung'' 1) was a system for injecting nitrous oxide (laughing gas) into aircraft engines that was used by the ''Luftwaffe'' in World War II. This increased the amount of oxygen in the fuel mi ...
system to boost the power output of
aircraft engine An aircraft engine, often referred to as an aero engine, is the power component of an aircraft propulsion system. Most aircraft engines are either piston engines or gas turbines, although a few have been rocket powered and in recent years many ...
s. Originally meant to provide the Luftwaffe standard aircraft with superior high-altitude performance, technological considerations limited its use to extremely high altitudes. Accordingly, it was only used by specialised planes such as high-altitude
reconnaissance aircraft A reconnaissance aircraft (colloquially, a spy plane) is a military aircraft designed or adapted to perform aerial reconnaissance with roles including collection of imagery intelligence (including using photography), signals intelligence, as ...
, high-speed bombers and high-altitude
interceptor aircraft An interceptor aircraft, or simply interceptor, is a type of fighter aircraft designed specifically for the defensive interception role against an attacking enemy aircraft, particularly bombers and reconnaissance aircraft. Aircraft that are c ...
. It sometimes could be found on Luftwaffe aircraft also fitted with another engine-boost system,
MW 50 MW 50 (Methanol-''Wasser'' 50) was a 50-50 mixture of methanol and water (German: ''Wasser'') that was often sprayed into the supercharger of World War II aircraft engines primarily for its anti-detonation effect, allowing the use of increased bo ...
, a form of water injection for aviation engines that used
methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a ...
for its boost capabilities. One of the major problems of using nitrous oxide in a reciprocating engine is that it can produce enough power to damage or destroy the engine. Very large power increases are possible, and if the mechanical structure of the engine is not properly reinforced, the engine may be severely damaged, or destroyed, during this kind of operation. It is very important with nitrous oxide augmentation of
petrol engine A petrol engine (gasoline engine in American English) is an internal combustion engine designed to run on petrol (gasoline). Petrol engines can often be adapted to also run on fuels such as liquefied petroleum gas and ethanol blends (such as ' ...
s to maintain proper
operating temperature An operating temperature is the allowable temperature range of the local ambient environment at which an electrical or mechanical device operates. The device will operate effectively within a specified temperature range which varies based on the de ...
s and fuel levels to prevent "pre-ignition", or "detonation" (sometimes referred to as "knock"). Most problems that are associated with nitrous oxide do not come from mechanical failure due to the power increases. Since nitrous oxide allows a much denser charge into the cylinder, it dramatically increases cylinder pressures. The increased pressure and temperature can cause problems such as melting the piston or valves. It also may crack or warp the piston or head and cause pre-ignition due to uneven heating. Automotive-grade liquid nitrous oxide differs slightly from medical-grade nitrous oxide. A small amount of
sulfur dioxide Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a toxic gas responsible for the odor of burnt matches. It is released naturally by volcanic activ ...
() is added to prevent substance abuse.


Aerosol propellant

The gas is approved for use as a
food additive Food additives are substances added to food to preserve flavor or enhance taste, appearance, or other sensory qualities. Some additives have been used for centuries as part of an effort to preserve food, for example vinegar (pickling), salt (salt ...
(
E number E numbers ("E" stands for "Europe") are codes for substances used as food additives, including those found naturally in many foods such as vitamin C, for use within the European Union (EU) and European Free Trade Association (EFTA). Commonly ...
: E942), specifically as an aerosol spray propellant. Its most common uses in this context are in aerosol
whipped cream Whipped cream is liquid heavy cream that is whipped by a whisk or mixer until it is light and fluffy and holds its shape, or by the expansion of dissolved gas, forming a firm colloid. It is often sweetened, typically with white sugar, and ...
canisters and
cooking spray Cooking spray is a spray form of an oil as a lubricant, lecithin as an emulsifier, and a propellant such as food-grade alcohol, nitrous oxide, carbon dioxide or propane. Cooking spray is applied to frying pans and other cookware to prevent foo ...
s. The gas is extremely soluble in fatty compounds. In aerosol whipped cream, it is dissolved in the fatty cream until it leaves the can, when it becomes gaseous and thus creates foam. Used in this way, it produces whipped cream which is four times the volume of the liquid, whereas whipping air into cream only produces twice the volume. If air were used as a propellant, oxygen would accelerate
rancidification Rancidification is the process of complete or incomplete autoxidation or hydrolysis of fats and oils when exposed to air, light, moisture, or bacterial action, producing short-chain aldehydes, ketones and free fatty acids. When these processes oc ...
of the butterfat, but nitrous oxide inhibits such degradation. Carbon dioxide cannot be used for whipped cream because it is acidic in water, which would curdle the cream and give it a seltzer-like "sparkling" sensation. The whipped cream produced with nitrous oxide is unstable, and will return to a more liquid state within half an hour to one hour. Thus, the method is not suitable for decorating food that will not be served immediately. During December 2016, some manufacturers reported a shortage of aerosol whipped creams in the United States due to an explosion at the
Air Liquide Air Liquide S.A. (; ; literally "liquid air"), is a French multinational company which supplies industrial gases and services to various industries including medical, chemical and electronic manufacturers. Founded in 1902, after Linde it is ...
nitrous oxide facility in
Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...
in late August. With a major facility offline, the disruption caused a shortage resulting in the company diverting the supply of nitrous oxide to medical clients rather than to food manufacturing. The shortage came during the
Christmas and holiday season The Christmas season or the festive season (also known in some countries as the holiday season or the holidays) is an annually recurring period recognized in many Western and other countries that is generally considered to run from late November ...
when canned whipped cream use is normally at its highest. Similarly, cooking spray, which is made from various types of oils combined with
lecithin Lecithin (, from the Greek ''lekithos'' "yolk") is a generic term to designate any group of yellow-brownish fatty substances occurring in animal and plant tissues which are amphiphilic – they attract both water and fatty substances (and so ar ...
(an
emulsifier An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloids. Altho ...
), may use nitrous oxide as a
propellant A propellant (or propellent) is a mass that is expelled or expanded in such a way as to create a thrust or other motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicles, the e ...
. Other propellants used in cooking spray include food-grade
alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...
and
propane Propane () is a three-carbon alkane with the molecular formula . It is a gas at standard temperature and pressure, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is commonly used a ...
.


Medicine

Nitrous oxide has been used in dentistry and surgery, as an anaesthetic and analgesic, since 1844. In the early days, the gas was administered through simple inhalers consisting of a breathing bag made of rubber cloth. Today, the gas is administered in hospitals by means of an automated relative analgesia machine, with an
anaesthetic vaporiser An anesthetic vaporizer (American English) or anaesthetic vaporiser (British English) is a device generally attached to an anesthetic machine which delivers a given concentration of a volatile anesthetic agent. It works by controlling the vap ...
and a
medical ventilator A ventilator is a piece of health technology, medical technology that provides mechanical ventilation by moving breathable air into and out of the lungs, to deliver breaths to a patient who is physically unable to breathe, or breathing insuffici ...
, that delivers a precisely dosed and breath-actuated flow of nitrous oxide mixed with oxygen in a 2:1 ratio. Nitrous oxide is a weak
general anaesthetic General anaesthetics (or anesthetics, see spelling differences) are often defined as compounds that induce a loss of consciousness in humans or loss of righting reflex in animals. Clinical definitions are also extended to include an induced coma ...
, and so is generally not used alone in general anaesthesia, but used as a carrier gas (mixed with oxygen) for more powerful general anaesthetic drugs such as
sevoflurane Sevoflurane, sold under the brand name Sevorane, among others, is a sweet-smelling, nonflammable, highly fluorinated methyl isopropyl ether used as an inhalational anaesthetic for induction and maintenance of general anesthesia. After desflura ...
or
desflurane Desflurane (1,2,2,2-tetrafluoroethyl difluoromethyl ether) is a highly fluorinated methyl ethyl ether used for maintenance of general anesthesia. Like halothane, enflurane, and isoflurane, it is a racemic mixture of (''R'') and (''S'') optical i ...
. It has a
minimum alveolar concentration Minimum alveolar concentration or MAC is the concentration, often expressed as a percentage by volume, of a vapour in the alveoli of the lungs that is needed to prevent movement (motor response) in 50% of subjects in response to surgical (pain) sti ...
of 105% and a blood/gas partition coefficient of 0.46. The use of nitrous oxide in anaesthesia, however, can increase the risk of postoperative nausea and vomiting. Dentists use a simpler machine which only delivers an / mixture for the patient to inhale while conscious. The patient is kept conscious throughout the procedure, and retains adequate mental faculties to respond to questions and instructions from the dentist. Inhalation of nitrous oxide is used frequently to relieve pain associated with
childbirth Childbirth, also known as labour and delivery, is the ending of pregnancy where one or more babies exits the internal environment of the mother via vaginal delivery or caesarean section. In 2019, there were about 140.11 million births globall ...
,
trauma Trauma most often refers to: * Major trauma, in physical medicine, severe physical injury caused by an external source * Psychological trauma, a type of damage to the psyche that occurs as a result of a severely distressing event *Traumatic i ...
, oral surgery and
acute coronary syndrome Acute coronary syndrome (ACS) is a syndrome (a set of signs and symptoms) due to decreased blood flow in the coronary arteries such that part of the heart muscle is unable to function properly or dies. The most common symptom is centrally loca ...
(includes heart attacks). Its use during labour has been shown to be a safe and effective aid for birthing women. Its use for acute coronary syndrome is of unknown benefit. In Britain and Canada,
Entonox Nitrous oxide, is an inhaled gas used as a pain medication and together with other medications for anesthesia. Common uses include during childbirth, following trauma, and as part of end-of-life care. Onset of effect is typically within half a m ...
and Nitronox are used commonly by ambulance crews (including unregistered practitioners) as rapid and highly effective analgesic gas. Fifty percent nitrous oxide can be considered for use by trained non-professional first aid responders in prehospital settings, given the relative ease and safety of administering 50% nitrous oxide as an analgesic. The rapid reversibility of its effect would also prevent it from precluding diagnosis.


Recreational use

Recreational inhalation of nitrous oxide, with the purpose of causing
euphoria Euphoria ( ) is the experience (or affect) of pleasure or excitement and intense feelings of well-being and happiness. Certain natural rewards and social activities, such as aerobic exercise, laughter, listening to or making music and da ...
and/or slight
hallucination A hallucination is a perception in the absence of an external stimulus that has the qualities of a real perception. Hallucinations are vivid, substantial, and are perceived to be located in external objective space. Hallucination is a combinatio ...
s, began as a phenomenon for the British upper class in 1799, known as "laughing gas parties". Starting in the nineteenth century, widespread availability of the gas for medical and culinary purposes allowed the recreational use to expand greatly throughout the world. In the United Kingdom, as of 2014, nitrous oxide was estimated to be used by almost half a million young people at nightspots, festivals and parties. Widespread recreational use of the drug throughout the UK was featured in the 2017
Vice A vice is a practice, behaviour, or habit generally considered immoral, sinful, criminal, rude, taboo, depraved, degrading, deviant or perverted in the associated society. In more minor usage, vice can refer to a fault, a negative character tra ...
documentary ''Inside The Laughing Gas Black Market'', in which journalist Matt Shea met with dealers of the drug who stole it from hospitals. A significant issue cited in London's press is the effect of nitrous oxide canister littering, which is highly visible and causes significant complaint from communities. Recreational users often misperceive nitrous oxide as a route to a "safe high", and are unaware of its potential for causing neurological damage. In Australia, recreation use became a public health concern following a rise in reported cases of neurotoxicity and a rise in
emergency room An emergency department (ED), also known as an accident and emergency department (A&E), emergency room (ER), emergency ward (EW) or casualty department, is a medical treatment facility specializing in emergency medicine, the acute care of pati ...
admissions, and in (the state of) South Australia legislation was passed in 2020 to restrict canister sales.


Safety

Nitrous oxide is a significant
occupational hazard An occupational hazard is a hazard experienced in the workplace. This encompasses many types of hazards, including chemical hazards, biological hazards (biohazards), psychosocial hazards, and physical hazards. In the United States, the Nation ...
for surgeons, dentists and nurses. Because nitrous oxide is minimally metabolised in humans (with a rate of 0.004%), it retains its potency when exhaled into the room by the patient, and can pose an intoxicating and prolonged exposure hazard to the clinic staff if the room is poorly ventilated. Where nitrous oxide is administered, a continuous-flow fresh-air ventilation system or
scavenger system {{Unreferenced, date=March 2009 A scavenger system is a medical device used in hospitals. It is used to gather gas or aerosolized medication after it is exhaled from the patient or left the area of the patient. Often used to collect anesthesia, ...
is used to prevent a waste-gas buildup. The
National Institute for Occupational Safety and Health The National Institute for Occupational Safety and Health (NIOSH, ) is the United States federal agency responsible for conducting research and making recommendations for the prevention of work-related injury and illness. NIOSH is part of the C ...
recommends that workers' exposure to nitrous oxide should be controlled during the administration of anaesthetic gas in medical, dental and veterinary operators. It set a
recommended exposure limit A recommended exposure limit (REL) is an occupational exposure limit that has been recommended by the United States National Institute for Occupational Safety and Health. The REL is a level that NIOSH believes would be protective of worker safety ...
(REL) of 25 ppm (46 mg/m3) to escaped anaesthetic.


Mental and manual impairment

Exposure to nitrous oxide causes short-term decreases in mental performance, audiovisual ability and manual dexterity. These effects coupled with the induced spatial and temporal disorientation could result in physical harm to the user from environmental hazards.


Neurotoxicity and neuroprotection

Nitrous oxide is
neurotoxic Neurotoxicity is a form of toxicity in which a biological, chemical, or physical agent produces an adverse effect on the structure or function of the central and/or peripheral nervous system. It occurs when exposure to a substance – specificall ...
and long-term or habitual use can cause severe neurological damage. Like other
NMDA receptor antagonist NMDA receptor antagonists are a class of drugs that work to antagonize, or inhibit the action of, the ''N''-Methyl-D-aspartate receptor (NMDAR). They are commonly used as anesthetics for animals and humans; the state of anesthesia they induce ...
s, it has been suggested that produces
neurotoxicity Neurotoxicity is a form of toxicity in which a biological, chemical, or physical agent produces an adverse effect on the structure or function of the central and/or peripheral nervous system. It occurs when exposure to a substance – specificall ...
in the form of
Olney's lesions Olney's lesions, also known as NMDA receptor antagonist neurotoxicity (NAN), are a form of potential brain damage due to drugs that have been studied experimentally and have produced neuronal damage, yet are administered by doctors to humans in the ...
in rodents upon prolonged (several hour) exposure. New research has arisen suggesting that Olney's lesions do not occur in humans, however, and similar drugs such as
ketamine Ketamine is a dissociative anesthetic used medically for induction and maintenance of anesthesia. It is also used as a recreational drug. It is one of the safest anesthetics, as, in contrast with opiates, ether, and propofol, it suppresses ne ...
are now believed not to be acutely neurotoxic. It has been argued that, because is rapidly expelled from the body under normal circumstances, it is less likely to be neurotoxic than other NMDAR antagonists. Indeed, in rodents, short-term exposure results in only mild injury that is rapidly reversible, and neuronal death occurs only after constant and sustained exposure. Nitrous oxide also may cause neurotoxicity after extended exposure because of hypoxia. This is especially true of non-medical formulations such as
whipped-cream charger A whipped cream charger is a steel cylinder or cartridge filled with nitrous oxide (N2O) that is used as a whipping agent in a whipped cream dispenser. The narrow end of a charger has a foil covering that is broken to release the gas. This is u ...
s (also known as "whippets" or "nangs"), which never contain oxygen, since oxygen makes cream rancid. In heavy (≥400 g or ≥200 L of gas in one session) or frequent (regular, e.g. daily or weekly) users reported to poison control centers, signs of
peripheral neuropathy Peripheral neuropathy, often shortened to neuropathy, is a general term describing disease affecting the peripheral nerves, meaning nerves beyond the brain and spinal cord. Damage to peripheral nerves may impair sensation, movement, gland, or or ...
have been noted: the presence of
ataxia Ataxia is a neurological sign consisting of lack of voluntary coordination of muscle movements that can include gait abnormality, speech changes, and abnormalities in eye movements. Ataxia is a clinical manifestation indicating dysfunction of ...
(gait abnormalities) or
paresthesia Paresthesia is an abnormal sensation of the skin (tingling, pricking, chilling, burning, numbness) with no apparent physical cause. Paresthesia may be transient or chronic, and may have any of dozens of possible underlying causes. Paresthesias ar ...
(perception of abnormal sensations, e.g. tingling, numbness, prickling, mostly in the extremities). These are considered an early sign of neurological damage and indicates
chronic toxicity Chronic toxicity, the development of adverse effects as a result of long term exposure to a contaminant or other stressor, is an important aspect of aquatic toxicology. Adverse effects associated with chronic toxicity can be directly lethal but are ...
. Nitrous oxide at 75% by volume reduces ischemia-induced neuronal death induced by occlusion of the middle cerebral artery in rodents, and decreases NMDA-induced Ca2+ influx in neuronal cell cultures, a critical event involved in
excitotoxicity In excitotoxicity, nerve cells suffer damage or death when the levels of otherwise necessary and safe neurotransmitters such as glutamate become pathologically high, resulting in excessive stimulation of receptors. For example, when glutamate re ...
.


DNA damage

Occupational exposure to ambient nitrous oxide has been associated with DNA damage, due to interruptions in DNA synthesis. This correlation is dose-dependent and does not appear to extend to casual recreational use; however, further research is needed to confirm the duration and quantity of exposure needed to cause damage.


Oxygen deprivation

If pure nitrous oxide is inhaled without oxygen mixed in, this can eventually lead to oxygen deprivation resulting in loss of blood pressure, fainting and even heart attacks. This can occur if the user inhales large quantities continuously, as with a strap-on mask connected to a gas canister. It can also happen if the user engages in excessive breath-holding or uses any other inhalation system that cuts off a supply of fresh air. A further risk is that symptoms of frostbite can occur on the lips,
larynx The larynx (), commonly called the voice box, is an organ in the top of the neck involved in breathing, producing sound and protecting the trachea against food aspiration. The opening of larynx into pharynx known as the laryngeal inlet is about ...
and bronchi if the gas is inhaled directly from the gas container. Therefore, nitrous oxide is often inhaled from condoms or balloons.


Vitamin B deficiency

Long-term exposure to nitrous oxide may cause vitamin B deficiency. This can cause serious neurotoxicity if the user has preexisting vitamin B deficiency. It inactivates the cobalamin form of vitamin B by oxidation. Symptoms of vitamin B deficiency, including
sensory neuropathy Peripheral neuropathy, often shortened to neuropathy, is a general term describing disease affecting the peripheral nerves, meaning nerves beyond the brain and spinal cord. Damage to peripheral nerves may impair sensation, movement, gland, or or ...
,
myelopathy Myelopathy describes any neurologic deficit related to the spinal cord. The most common form of myelopathy in humans, ''Spinal cord compression, cervical spondylotic myelopathy (CSM)'', also called ''degenerative cervical myelopathy'', results fro ...
and
encephalopathy Encephalopathy (; from grc, ἐνκέφαλος "brain" + πάθος "suffering") means any disorder or disease of the brain, especially chronic degenerative conditions. In modern usage, encephalopathy does not refer to a single disease, but r ...
, may occur within days or weeks of exposure to nitrous oxide anaesthesia in people with subclinical vitamin B deficiency. Symptoms are treated with high doses of vitamin B, but recovery can be slow and incomplete. People with normal vitamin B levels have stores to make the effects of nitrous oxide insignificant, unless exposure is repeated and prolonged (nitrous oxide abuse). Vitamin B levels should be checked in people with risk factors for vitamin B deficiency prior to using nitrous oxide anaesthesia.


Prenatal development

Several experimental studies in rats indicate that chronic exposure of pregnant females to nitrous oxide may have adverse effects on the developing fetus.


Chemical/physical risks

At room temperature () the saturated vapour pressure is 50.525 bar, rising up to 72.45 bar at —the
critical temperature Critical or Critically may refer to: *Critical, or critical but stable, medical states **Critical, or intensive care medicine *Critical juncture, a discontinuous change studied in the social sciences. *Critical Software, a company specializing in ...
. The pressure curve is thus unusually sensitive to temperature. As with many strong oxidisers, contamination of parts with fuels have been implicated in rocketry accidents, where small quantities of nitrous/fuel mixtures explode due to "
water hammer Hydraulic shock (colloquial: water hammer; fluid hammer) is a pressure surge or wave caused when a fluid in motion, usually a liquid but sometimes also a gas is forced to stop or change direction suddenly; a momentum change. This phenomenon com ...
"-like effects (sometimes called "dieseling"—heating due to adiabatic compression of gases can reach decomposition temperatures). Some common building materials such as stainless steel and aluminium can act as fuels with strong oxidisers such as nitrous oxide, as can contaminants that may ignite due to adiabatic compression. There also have been incidents where nitrous oxide decomposition in plumbing has led to the explosion of large tanks.


Mechanism of action

The pharmacological
mechanism of action In pharmacology, the term mechanism of action (MOA) refers to the specific biochemical interaction through which a drug substance produces its pharmacological effect. A mechanism of action usually includes mention of the specific molecular targe ...
of in medicine is not fully known. However, it has been shown to directly modulate a broad range of
ligand-gated ion channel Ligand-gated ion channels (LICs, LGIC), also commonly referred to as ionotropic receptors, are a group of transmembrane ion-channel proteins which open to allow ions such as Na+, K+, Ca2+, and/or Cl− to pass through the membrane in res ...
s, and this likely plays a major role in many of its effects. It moderately blocks
NMDAR The ''N''-methyl-D-aspartate receptor (also known as the NMDA receptor or NMDAR), is a glutamate receptor and ion channel found in neurons. The NMDA receptor is one of three types of ionotropic glutamate receptors, the other two being AMPA and ...
and β-subunit-containing nACh channels, weakly inhibits
AMPA α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, better known as AMPA, is a compound that is a specific agonist for the AMPA receptor, where it mimics the effects of the neurotransmitter glutamate. There are several types of glutamatergic ...
,
kainate Kainic acid, or kainate, is an acid that naturally occurs in some seaweed. Kainic acid is a potent neuroexcitatory amino acid agonist that acts by activating receptors for glutamate, the principal excitatory neurotransmitter in the central nervo ...
, GABA and 5-HT receptors, and slightly potentiates GABA and
glycine receptor The glycine receptor (abbreviated as GlyR or GLR) is the receptor of the amino acid neurotransmitter glycine. GlyR is an ionotropic receptor that produces its effects through chloride current. It is one of the most widely distributed inhibitory ...
s. It also has been shown to activate two-pore-domain channels. While affects quite a few ion channels, its anaesthetic,
hallucinogenic Hallucinogens are a large, diverse class of psychoactive drugs that can produce altered states of consciousness characterized by major alterations in thought, mood, and perception as well as other changes. Most hallucinogens can be categorize ...
and
euphoriant Euphoria ( ) is the experience (or affect) of pleasure or excitement and intense feelings of well-being and happiness. Certain natural rewards and social activities, such as aerobic exercise, laughter, listening to or making music and danci ...
effects are likely caused predominantly, or fully, via inhibition of NMDA receptor-mediated currents. In addition to its effects on ion channels, may act to imitate
nitric oxide Nitric oxide (nitrogen oxide or nitrogen monoxide) is a colorless gas with the formula . It is one of the principal oxides of nitrogen. Nitric oxide is a free radical: it has an unpaired electron, which is sometimes denoted by a dot in its che ...
(NO) in the central nervous system, and this may be related to its
analgesic An analgesic drug, also called simply an analgesic (American English), analgaesic (British English), pain reliever, or painkiller, is any member of the group of drugs used to achieve relief from pain (that is, analgesia or pain management). It ...
and
anxiolytic An anxiolytic (; also antipanic or antianxiety agent) is a medication or other intervention that reduces anxiety. This effect is in contrast to anxiogenic agents which increase anxiety. Anxiolytic medications are used for the treatment of anxi ...
properties. Nitrous oxide is 30 to 40 times more soluble than nitrogen. The effects of inhaling sub-anaesthetic doses of nitrous oxide have been known to vary, based on several factors, including settings and individual differences; however, from his discussion, Jay (2008) suggests that it has been reliably known to induce the following states and sensations: * Intoxication * Euphoria/dysphoria * Spatial disorientation * Temporal disorientation * Reduced pain sensitivity A minority of users also will present with uncontrolled vocalisations and muscular spasms. These effects generally disappear minutes after removal of the nitrous oxide source.


Anxiolytic effect

In behavioural tests of
anxiety Anxiety is an emotion which is characterized by an unpleasant state of inner turmoil and includes feelings of dread over anticipated events. Anxiety is different than fear in that the former is defined as the anticipation of a future threat wh ...
, a low dose of is an effective anxiolytic, and this anti-anxiety effect is associated with enhanced activity of GABA receptors, as it is partially reversed by
benzodiazepine receptor The GABAA receptor (GABAAR) is an ionotropic receptor and ligand-gated ion channel. Its endogenous ligand is γ-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system. Upon opening, the GABAA receptor on ...
antagonists An antagonist is a character in a story who is presented as the chief foe of the protagonist. Etymology The English word antagonist comes from the Greek ἀνταγωνιστής – ''antagonistēs'', "opponent, competitor, villain, enemy, riv ...
. Mirroring this, animals that have developed tolerance to the anxiolytic effects of
benzodiazepine Benzodiazepines (BZD, BDZ, BZs), sometimes called "benzos", are a class of depressant drugs whose core chemical structure is the fusion of a benzene ring and a diazepine ring. They are prescribed to treat conditions such as anxiety disorders, ...
s are partially tolerant to . Indeed, in humans given 30% , benzodiazepine receptor antagonists reduced the subjective reports of feeling "high", but did not alter psychomotor performance, in human clinical studies.


Analgesic effect

The analgesic effects of are linked to the interaction between the
endogenous opioid Opioid peptides are peptides that bind to opioid receptors in the brain; opiates and opioids mimic the effect of these peptides. Such peptides may be produced by the body itself, for example endorphins. The effects of these peptides vary, but th ...
system and the descending
noradrenergic Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as both a hormone and neurotransmitter. The name "noradrenaline" (from Latin '' ad'', ...
system. When animals are given morphine chronically, they develop tolerance to its pain-killing effects, and this also renders the animals tolerant to the analgesic effects of . Administration of
antibodies An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...
that bind and block the activity of some endogenous opioids (not
β-endorphin ''beta''-Endorphin (β-endorphin) is an endogenous opioid neuropeptide and peptide hormone that is produced in certain neurons within the central nervous system and peripheral nervous system. It is one of three endorphins that are produced in ...
) also block the antinociceptive effects of . Drugs that inhibit the breakdown of endogenous opioids also potentiate the antinociceptive effects of . Several experiments have shown that opioid receptor antagonists applied directly to the brain block the antinociceptive effects of , but these drugs have no effect when injected into the
spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spi ...
. Apart from an indirect action, nitrous oxide, like morphine also interacts directly with the endogenous opioid system by binding at opioid receptor binding sites. Conversely,
α-adrenoceptor The adrenergic receptors or adrenoceptors are a class of G protein-coupled receptors that are targets of many catecholamines like norepinephrine (noradrenaline) and epinephrine (adrenaline) produced by the body, but also many medications like beta ...
antagonists block the pain-reducing effects of when given directly to the spinal cord, but not when applied directly to the brain. Indeed,
α-adrenoceptor The adrenergic receptors or adrenoceptors are a class of G protein-coupled receptors that are targets of many catecholamines like norepinephrine (noradrenaline) and epinephrine (adrenaline) produced by the body, but also many medications like beta ...
knockout mice or animals depleted in
norepinephrine Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as both a hormone and neurotransmitter. The name "noradrenaline" (from Latin '' ad'', ...
are nearly completely resistant to the antinociceptive effects of . Apparently -induced release of endogenous opioids causes disinhibition of
brainstem The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is cont ...
noradrenergic neurons, which release norepinephrine into the spinal cord and inhibit pain signalling. Exactly how causes the release of endogenous opioid peptides remains uncertain.


Properties and reactions

Nitrous oxide is a colourless, non-toxic gas with a faint, sweet odour. Nitrous oxide supports combustion by releasing the dipolar bonded oxygen radical, and can thus relight a glowing splint. is inert at room temperature and has few reactions. At elevated temperatures, its reactivity increases. For example, nitrous oxide reacts with at to give : : 2 + → + NaOH + The above reaction is the route adopted by the commercial chemical industry to produce
azide In chemistry, azide is a linear, polyatomic anion with the formula and structure . It is the conjugate base of hydrazoic acid . Organic azides are organic compounds with the formula , containing the azide functional group. The dominant applic ...
salts, which are used as detonators.


History

The gas was first synthesised in 1772 by English
natural philosopher Natural philosophy or philosophy of nature (from Latin ''philosophia naturalis'') is the philosophical study of physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior throu ...
and chemist
Joseph Priestley Joseph Priestley (; 24 March 1733 – 6 February 1804) was an English chemist, natural philosopher, separatist theologian, grammarian, multi-subject educator, and liberal political theorist. He published over 150 works, and conducted exp ...
who called it ''dephlogisticated nitrous air'' (see
phlogiston theory The phlogiston theory is a superseded scientific theory that postulated the existence of a fire-like element called phlogiston () contained within combustible bodies and released during combustion. The name comes from the Ancient Greek (''burni ...
) or ''inflammable nitrous air''. Priestley published his discovery in the book ''Experiments and Observations on Different Kinds of Air (1775)'', where he described how to produce the preparation of "nitrous air diminished", by heating iron filings dampened with
nitric acid Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitri ...
.


Early use

The first important use of nitrous oxide was made possible by
Thomas Beddoes Thomas Beddoes (13 April 176024 December 1808) was an English physician and scientific writer. He was born in Shifnal, Shropshire and died in Bristol fifteen years after opening his medical practice there. He was a reforming practitioner and te ...
and
James Watt James Watt (; 30 January 1736 (19 January 1736 OS) – 25 August 1819) was a Scottish inventor, mechanical engineer, and chemist who improved on Thomas Newcomen's 1712 Newcomen steam engine with his Watt steam engine in 1776, which was fun ...
, who worked together to publish the book ''Considerations on the Medical Use and on the Production of Factitious Airs (1794)''. This book was important for two reasons. First, James Watt had invented a novel machine to produce "
factitious airs Factitious airs was a term used for synthetic gases which emerged around 1670 when Robert Boyle coined the term upon isolating what is now understood to be hydrogen. ''Factitious'' means "artificial, not natural", so the term means "man-made gases ...
" (including nitrous oxide) and a novel "breathing apparatus" to inhale the gas. Second, the book also presented the new medical theories by Thomas Beddoes, that
tuberculosis Tuberculosis (TB) is an infectious disease usually caused by '' Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, in ...
and other lung diseases could be treated by inhalation of "Factitious Airs". The machine to produce "Factitious Airs" had three parts: a furnace to burn the needed material, a vessel with water where the produced gas passed through in a spiral pipe (for impurities to be "washed off"), and finally the gas cylinder with a gasometer where the gas produced, "air", could be tapped into portable air bags (made of airtight oily silk). The breathing apparatus consisted of one of the portable air bags connected with a tube to a mouthpiece. With this new equipment being engineered and produced by 1794, the way was paved for
clinical trial Clinical trials are prospective biomedical or behavioral research studies on human participants designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel vaccines, drugs, dietar ...
s, which began in 1798 when Thomas Beddoes established the ''"
Pneumatic Institution The Pneumatic Institution (also referred to as Pneumatic Institute) was a medical research facility in Bristol, England, in 1799–1802. It was established by physician and science writer Thomas Beddoes to study the medical effects of gases, know ...
for Relieving Diseases by Medical Airs"'' in Hotwells (
Bristol Bristol () is a city, ceremonial county and unitary authority in England. Situated on the River Avon, it is bordered by the ceremonial counties of Gloucestershire to the north and Somerset to the south. Bristol is the most populous city in ...
). In the basement of the building, a large-scale machine was producing the gases under the supervision of a young Humphry Davy, who was encouraged to experiment with new gases for patients to inhale. The first important work of Davy was examination of the nitrous oxide, and the publication of his results in the book: ''Researches, Chemical and Philosophical (1800)''. In that publication, Davy notes the analgesic effect of nitrous oxide at page 465 and its potential to be used for surgical operations at page 556. Davy coined the name "laughing gas" for nitrous oxide. Despite Davy's discovery that inhalation of nitrous oxide could relieve a conscious person from pain, another 44 years elapsed before doctors attempted to use it for
anaesthesia Anesthesia is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prevention of pain), paralysis (muscle relaxation), am ...
. The use of nitrous oxide as a
recreational drug Recreational drug use indicates the use of one or more psychoactive drugs to induce an altered state of consciousness either for pleasure or for some other casual purpose or pastime by modifying the perceptions and emotions of the user. When a ...
at "laughing gas parties", primarily arranged for the British upper class, became an immediate success beginning in 1799. While the effects of the gas generally make the user appear stuporous, dreamy and sedated, some people also "get the giggles" in a state of euphoria, and frequently erupt in laughter. One of the earliest commercial producers in the U.S. was
George Poe George Poe, Jr. (May 8, 1846 – February 3, 1914) was a pioneer of mechanical ventilation of asphyxiation victims. He was the first person to manufacture nitrous oxide for commercial use in his Trenton, New Jersey company. Birth He was t ...
, cousin of the poet
Edgar Allan Poe Edgar Allan Poe (; Edgar Poe; January 19, 1809 – October 7, 1849) was an American writer, poet, editor, and literary critic. Poe is best known for his poetry and short stories, particularly his tales of mystery and the macabre. He is wide ...
, who also was the first to liquefy the gas.


Anaesthetic use

The first time nitrous oxide was used as an anaesthetic drug in the treatment of a patient was when dentist
Horace Wells Horace Wells (January 21, 1815 – January 24, 1848) was an American dentist who pioneered the use of anesthesia in dentistry, specifically the use of nitrous oxide (or laughing gas). Early life Wells was the first of three children of H ...
, with assistance by
Gardner Quincy Colton Gardner Quincy Colton (February 7, 1814, Georgia, Vermont – August 10, 1898, Geneva, Switzerland) was an American showman, medicine man, lecturer, and former medical student who pioneered the use of nitrous oxide, or laughing gas, in dentistr ...
and
John Mankey Riggs John Mankey Riggs (October 25, 1811 – November 11, 1885) was the leading authority on periodontal disease and its treatment in the United States, to the point that periodontal disease was known as " Riggs' disease."Shklar, G; Carranza, FA: The H ...
, demonstrated insensitivity to pain from a
dental extraction A dental extraction (also referred to as tooth extraction, exodontia, exodontics, or informally, tooth pulling) is the removal of teeth from the dental alveolus (socket) in the alveolar bone. Extractions are performed for a wide variety of reason ...
on 11 December 1844. In the following weeks, Wells treated the first 12 to 15 patients with nitrous oxide in
Hartford, Connecticut Hartford is the capital city of the U.S. state of Connecticut. It was the seat of Hartford County until Connecticut disbanded county government in 1960. It is the core city in the Greater Hartford metropolitan area. Census estimates since the ...
, and, according to his own record, only failed in two cases. In spite of these convincing results having been reported by Wells to the medical society in
Boston Boston (), officially the City of Boston, is the state capital and most populous city of the Commonwealth of Massachusetts, as well as the cultural and financial center of the New England region of the United States. It is the 24th- mo ...
in December 1844, this new method was not immediately adopted by other dentists. The reason for this was most likely that Wells, in January 1845 at his first public demonstration to the medical faculty in Boston, had been partly unsuccessful, leaving his colleagues doubtful regarding its efficacy and safety. The method did not come into general use until 1863, when Gardner Quincy Colton successfully started to use it in all his "Colton Dental Association" clinics, that he had just established in
New Haven New Haven is a city in the U.S. state of Connecticut. It is located on New Haven Harbor on the northern shore of Long Island Sound in New Haven County, Connecticut and is part of the New York City metropolitan area. With a population of 134,02 ...
and
New York City New York, often called New York City or NYC, is the List of United States cities by population, most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the L ...
. Over the following three years, Colton and his associates successfully administered nitrous oxide to more than 25,000 patients. Today, nitrous oxide is used in dentistry as an anxiolytic, as an adjunct to
local anaesthetic A local anesthetic (LA) is a medication that causes absence of pain sensation. In the context of surgery, a local anesthetic creates an absence of pain in a specific location of the body without a loss of consciousness, as opposed to a general an ...
. Nitrous oxide was not found to be a strong enough anaesthetic for use in major surgery in hospital settings, however. Instead,
diethyl ether Diethyl ether, or simply ether, is an organic compound in the ether class with the formula , sometimes abbreviated as (see Pseudoelement symbols). It is a colourless, highly volatile, sweet-smelling ("ethereal odour"), extremely flammable liq ...
, being a stronger and more potent anaesthetic, was demonstrated and accepted for use in October 1846, along with
chloroform Chloroform, or trichloromethane, is an organic compound with chemical formula, formula Carbon, CHydrogen, HChlorine, Cl3 and a common organic solvent. It is a colorless, strong-smelling, dense liquid produced on a large scale as a precursor to ...
in 1847. When
Joseph Thomas Clover Joseph Thomas Clover (28 February 1825; baptised 7 May 1825 – 27 September 1882) was an English doctor and pioneer of anesthesiology, anaesthesia. He invented a variety of pieces of apparatus to deliver anaesthetics including ether and chloro ...
invented the "gas-ether inhaler" in 1876, however, it became a common practice at hospitals to initiate all anaesthetic treatments with a mild flow of nitrous oxide, and then gradually increase the anaesthesia with the stronger ether or chloroform. Clover's gas-ether inhaler was designed to supply the patient with nitrous oxide and ether at the same time, with the exact mixture being controlled by the operator of the device. It remained in use by many hospitals until the 1930s. Although hospitals today use a more advanced anaesthetic machine, these machines still use the same principle launched with Clover's gas-ether inhaler, to initiate the anaesthesia with nitrous oxide, before the administration of a more powerful anaesthetic.


As a patent medicine

Colton's popularisation of nitrous oxide led to its adoption by a number of less than reputable quacksalvers, who touted it as a cure for
consumption Consumption may refer to: *Resource consumption *Tuberculosis, an infectious disease, historically * Consumption (ecology), receipt of energy by consuming other organisms * Consumption (economics), the purchasing of newly produced goods for curren ...
, scrofula,
catarrh Catarrh is an exudate of inflamed mucous membranes in one of the airways or cavities of the body, usually with reference to the throat and paranasal sinuses. It can result in a thick exudate of mucus and white blood cells caused by the swelling o ...
and other diseases of the blood, throat and lungs. Nitrous oxide treatment was administered and licensed as a
patent medicine A patent medicine, sometimes called a proprietary medicine, is an over-the-counter (nonprescription) medicine or medicinal preparation that is typically protected and advertised by a trademark and trade name (and sometimes a patent) and claimed ...
by the likes of
C. L. Blood Charles Lewis Blood (September 8, 1835 – September 27, 1908; alias C. H. Lewis '' et al.'') was an American con artist and self-styled physician who operated in Boston, New York City, Philadelphia, and Chicago. He produced a patent medicine t ...
and Jerome Harris in Boston and Charles E. Barney of Chicago.


Production

Reviewing various methods of producing nitrous oxide is published.


Industrial methods

Nitrous oxide is prepared on an industrial scale by careful heating of
ammonium nitrate Ammonium nitrate is a chemical compound with the chemical formula . It is a white crystalline salt consisting of ions of ammonium and nitrate. It is highly soluble in water and hygroscopic as a solid, although it does not form hydrates. It is ...
at about 250 °C, which decomposes into nitrous oxide and water vapour. : → 2 + The addition of various
phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phospho ...
salts favours formation of a purer gas at slightly lower temperatures. This reaction may be difficult to control, resulting in
detonation Detonation () is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations propagate supersonically through shock waves with ...
.


Laboratory methods

The decomposition of ammonium nitrate is also a common laboratory method for preparing the gas. Equivalently, it can be obtained by heating a mixture of
sodium nitrate Sodium nitrate is the chemical compound with the formula . This alkali metal nitrate salt is also known as Chile saltpeter (large deposits of which were historically mined in Chile) to distinguish it from ordinary saltpeter, potassium nitrate. T ...
and
ammonium sulfate Ammonium sulfate (American English and international scientific usage; ammonium sulphate in British English); (NH4)2SO4, is an inorganic salt with a number of commercial uses. The most common use is as a soil fertilizer. It contains 21% nitrogen a ...
: :2 + () → + 2 + 4 Another method involves the reaction of urea, nitric acid and sulfuric acid: :2 (NH)CO + 2 + → 2 + 2 + (NH)SO + 2 Direct oxidation of ammonia with a
manganese dioxide Manganese dioxide is the inorganic compound with the formula . This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese and a component of manganese nodules. The principal use for is for dry-cell ...
-
bismuth oxide Bismuth(III) oxide is perhaps the most industrially important compound of bismuth. It is also a common starting point for bismuth chemistry. It is found naturally as the mineral bismite (monoclinic) and sphaerobismoite (tetragonal, much more rare) ...
catalyst has been reported: cf.
Ostwald process The Ostwald process is a chemical process used for making nitric acid (HNO3). Wilhelm Ostwald developed the process, and he patented it in 1902. The Ostwald process is a mainstay of the modern chemical industry, and it provides the main raw materi ...
. :2 + 2 → + 3
Hydroxylammonium chloride Hydroxylammonium chloride is the hydrochloric acid salt of hydroxylamine. Hydroxylamine is a biological intermediate in nitrification (biological oxidation of ammonia with oxygen into nitrite) and in anammox (biological oxidation of nitrite and am ...
reacts with
sodium nitrite Sodium nitrite is an inorganic compound with the chemical formula NaNO2. It is a white to slightly yellowish crystalline powder that is very soluble in water and is hygroscopic. From an industrial perspective, it is the most important nitrite ...
to give nitrous oxide. If the nitrite is added to the hydroxylamine solution, the only remaining by-product is salt water. If the hydroxylamine solution is added to the nitrite solution (nitrite is in excess), however, then toxic higher oxides of nitrogen also are formed: : + → + NaCl + 2 Treating with and HCl also has been demonstrated: :2 + 8 HCl + 4 → 5 + 4 +
Hyponitrous acid Hyponitrous acid is a chemical compound with formula or HON=NOH. It is an isomer of nitramide, H2N−NO2; and a formal dimer of azanone, HNO. Hyponitrous acid forms two series of salts, the hyponitrites containing the N=NOsup>2− anion, and t ...
decomposes to NO and water with a
half-life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ato ...
of 16 days at 25 °C at pH 1–3.Egon Wiberg, Arnold Frederick Holleman (2001) ''Inorganic Chemistry'', Elsevier :HNO→ HO + NO


Atmospheric occurrence

Nitrous oxide is a minor component of Earth's atmosphere and is an active part of the planetary
nitrogen cycle The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmospheric, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biologi ...
. Based on analysis of air samples gathered from sites around the world, its
concentration In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', ''molar concentration'', ''number concentration'', an ...
surpassed 330  ppb in 2017. The growth rate of about 1 ppb per year has also accelerated during recent decades. Nitrous oxide's atmospheric abundance has grown more than 20% from a base level of about 270 ppb in year 1750. Important atmospheric properties of are summarized in the following table: In October 2020 scientists published a comprehensive quantification of global sources and sinks. They report that human-induced emissions increased by 30% over the past four decades and are the main cause of the increase in atmospheric concentration. The recent growth has exceeded some of the highest projected emission scenarios.


Emissions by source

As of 2010, it was estimated that about 29.5 million
tonne The tonne ( or ; symbol: t) is a unit of mass equal to 1000  kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
s of (containing 18.8 million tonnes of nitrogen) were entering the atmosphere each year; of which 64% were natural, and 36% due to human activity.U.S. Environmental Protection Agency (2010),
Methane and Nitrous Oxide Emissions from Natural Sources
. Report EPA 430-R-10-001.
Most of the emitted into the atmosphere, from natural and anthropogenic sources, is produced by
microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
s such as
denitrifying bacteria Denitrifying bacteria are a diverse group of bacteria that encompass many different phyla. This group of bacteria, together with denitrifying fungi and archaea, is capable of performing denitrification as part of the nitrogen cycle. Denitrification ...
and
fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
in soils and oceans. Soils under natural vegetation are an important source of nitrous oxide, accounting for 60% of all naturally produced emissions. Other natural sources include the oceans (35%) and atmospheric chemical reactions (5%).
Wetlands A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...
can also be emitters of nitrous oxide. A 2019 study showed that emissions from thawing permafrost are 12 times higher than previously assumed. The main components of anthropogenic emissions are fertilised agricultural soils and livestock manure (42%), runoff and leaching of fertilisers (25%), biomass burning (10%), fossil fuel combustion and industrial processes (10%), biological degradation of other nitrogen-containing atmospheric emissions (9%) and human
sewage Sewage (or domestic sewage, domestic wastewater, municipal wastewater) is a type of wastewater that is produced by a community of people. It is typically transported through a sewer system. Sewage consists of wastewater discharged from residenc ...
(5%).K. L. Denman, G. Brasseur, et al. (2007), "Couplings Between Changes in the Climate System and Biogeochemistry". In ''Fourth Assessment Report of the Intergovernmental Panel on Climate Change'', Cambridge University Press. Agriculture enhances nitrous oxide production through soil cultivation, the use of nitrogen
fertilisers A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...
and animal waste handling. These activities stimulate naturally occurring bacteria to produce more nitrous oxide. Nitrous oxide emissions from soil can be challenging to measure as they vary markedly over time and space, and the majority of a year's emissions may occur when conditions are favorable during "hot moments" and/or at favorable locations known as "hotspots". Among industrial emissions, the production of nitric acid and
adipic acid Adipic acid or hexanedioic acid is the organic compound with the formula (CH2)4(COOH)2. From an industrial perspective, it is the most important dicarboxylic acid: about 2.5 billion kilograms of this white crystalline powder are produced annuall ...
are the largest sources of nitrous oxide emissions. The adipic acid emissions specifically arise from the degradation of the
nitrolic acid Nitrolic acids are organic compounds with the functional group RC(NO2)=NOH. They are prepared by the reaction of nitroalkanes with base and nitrite sources: :RCH2NO2 + HNO2 → RC(NO2)=NOH + H2O The conversion was first demonstrated by V ...
intermediate derived from nitration of cyclohexanone.


Biological processes

Natural processes that generate nitrous oxide may be classified as
nitrification ''Nitrification'' is the biological oxidation of ammonia to nitrite followed by the oxidation of the nitrite to nitrate occurring through separate organisms or direct ammonia oxidation to nitrate in comammox bacteria. The transformation of amm ...
and
denitrification Denitrification is a microbially facilitated process where nitrate (NO3−) is reduced and ultimately produces molecular nitrogen (N2) through a series of intermediate gaseous nitrogen oxide products. Facultative anaerobic bacteria perform denitr ...
. Specifically, they include: * aerobic autotrophic nitrification, the stepwise oxidation of
ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous was ...
() to
nitrite The nitrite polyatomic ion, ion has the chemical formula . Nitrite (mostly sodium nitrite) is widely used throughout chemical and pharmaceutical industries. The nitrite anion is a pervasive intermediate in the nitrogen cycle in nature. The name ...
() and to
nitrate Nitrate is a polyatomic ion A polyatomic ion, also known as a molecular ion, is a covalent bonded set of two or more atoms, or of a metal complex, that can be considered to behave as a single unit and that has a net charge that is not zer ...
() * anaerobic heterotrophic denitrification, the stepwise reduction of to ,
nitric oxide Nitric oxide (nitrogen oxide or nitrogen monoxide) is a colorless gas with the formula . It is one of the principal oxides of nitrogen. Nitric oxide is a free radical: it has an unpaired electron, which is sometimes denoted by a dot in its che ...
(NO), and ultimately , where facultative anaerobe bacteria use as an electron acceptor in the respiration of organic material in the condition of insufficient oxygen () * nitrifier denitrification, which is carried out by autotrophic -oxidising bacteria and the pathway whereby ammonia () is oxidised to nitrite (), followed by the reduction of to nitric oxide (NO), and molecular nitrogen () * heterotrophic nitrification * aerobic denitrification by the same heterotrophic nitrifiers * fungal denitrification * non-biological chemodenitrification These processes are affected by soil chemical and physical properties such as the availability of mineral nitrogen and
organic matter Organic matter, organic material, or natural organic matter refers to the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have c ...
, acidity and soil type, as well as climate-related factors such as soil temperature and water content. The emission of the gas to the atmosphere is limited greatly by its consumption inside the cells, by a process catalysed by the enzyme nitrous oxide reductase.


Environmental impact


Greenhouse effect

Nitrous oxide has significant
global warming potential Global warming potential (GWP) is the heat absorbed by any greenhouse gas in the atmosphere, as a multiple of the heat that would be absorbed by the same mass of carbon dioxide (). GWP is 1 for . For other gases it depends on the gas and the time f ...
as a
greenhouse gas A greenhouse gas (GHG or GhG) is a gas that Absorption (electromagnetic radiation), absorbs and Emission (electromagnetic radiation), emits radiant energy within the thermal infrared range, causing the greenhouse effect. The primary greenhouse ...
. On a per-molecule basis, considered over a 100-year period, nitrous oxide has 265 times the atmospheric heat-trapping ability of
carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
(). However, because of its low concentration (less than 1/1,000 of that of ), its contribution to the
greenhouse effect The greenhouse effect is a process that occurs when energy from a planet's host star goes through the planet's atmosphere and heats the planet's surface, but greenhouse gases in the atmosphere prevent some of the heat from returning directly ...
is less than one third that of carbon dioxide, and also less than
water vapour (99.9839 °C) , - , Boiling point , , - , specific gas constant , 461.5 J/( kg·K) , - , Heat of vaporization , 2.27 MJ/kg , - , Heat capacity , 1.864 kJ/(kg·K) Water vapor, water vapour or aqueous vapor is the gaseous pha ...
and
methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...
.US Environmental Protection Agency,
Climate Change Indicators: Atmospheric Concentrations of Greenhouse Gases
Web document, accessed on 2017-02-14
On the other hand, since 38% or more of the entering the atmosphere is the result of human activity, control of nitrous oxide is considered part of efforts to curb greenhouse gas emissions. A 2008 study by
Nobel Laureate The Nobel Prizes ( sv, Nobelpriset, no, Nobelprisen) are awarded annually by the Royal Swedish Academy of Sciences, the Swedish Academy, the Karolinska Institutet, and the Norwegian Nobel Committee to individuals and organizations who make out ...
Paul Crutzen Paul Jozef Crutzen (; 3 December 1933 – 28 January 2021) was a Dutch meteorologist and atmospheric chemist. He was awarded the Nobel Prize in Chemistry in 1995 for his work on atmospheric chemistry and specifically for his efforts in studying ...
suggests that the amount of nitrous oxide release attributable to agricultural nitrate
fertiliser A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...
s has been seriously underestimated, most of which presumably, would come under
soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...
and
ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wo ...
ic release in the
Environmental Protection Agency A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale f ...
data. Nitrous oxide is released into the atmosphere through agriculture, when farmers add nitrogen-based fertilizers onto the fields, and through the breakdown of animal manure. Approximately 79 percent of all nitrous oxide released in the United States came from nitrogen fertilization. Reduction of emissions can be a hot topic in the
politics of climate change The politics of climate change results from different perspectives on how to respond to climate change. Global warming is driven largely by the emissions of greenhouse gases due to human economic activity, especially the burning of fossil fuels, ...
. Nitrous oxide is also released as a by-product of burning fossil fuel, though the amount released depends on which fuel was used. It is also emitted through the manufacture of
nitric acid Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitri ...
, which is used in the synthesis of nitrogen fertilizers. The production of adipic acid, a precursor to
nylon Nylon is a generic designation for a family of synthetic polymers composed of polyamides ( repeating units linked by amide links).The polyamides may be aliphatic or semi-aromatic. Nylon is a silk-like thermoplastic, generally made from petro ...
and other synthetic clothing fibres, also releases nitrous oxide. The total amount of nitrous oxide released that is of human origins is about 40 percent.


Ozone layer depletion

Nitrous oxide has also been implicated in thinning the ozone layer. A 2009 study suggested that emission was the single most important ozone-depleting emission and it was expected to remain the largest throughout the 21st century.


Legality

In the United States, possession of nitrous oxide is legal under federal law and is not subject to
DEA The Drug Enforcement Administration (DEA; ) is a United States federal law enforcement agency under the U.S. Department of Justice tasked with combating drug trafficking and distribution within the U.S. It is the lead agency for domestic en ...
purview. It is, however, regulated by the
Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...
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. 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 special license. For example, in the state of California, possession for recreational use is prohibited and qualifies as a misdemeanor. In August 2015, the
Council A council is a group of people who come together to consult, deliberate, or make decisions. A council may function as a legislature, especially at a town, city or county/shire level, but most legislative bodies at the state/provincial or natio ...
of the
London Borough of Lambeth Lambeth () is a London boroughs, London borough in South London, England, which forms part of Inner London. Its name was recorded in 1062 as ''Lambehitha'' ("landing place for lambs") and in 1255 as ''Lambeth''. The geographical centre of London ...
( UK) banned the use of the drug for recreational purposes, making offenders liable to an on-the-spot fine of up to £1,000. 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 nitrous oxide, although it is implied that only recreational use will be targeted legally. In India, transfer of nitrous oxide from bulk cylinders to smaller, more transportable E-type, 1,590-litre-capacity tanks is legal when the intended use of the gas is for medical anaesthesia.


See also

* DayCent *
Fink effect The Fink effect, also known as "diffusion anoxia", "diffusion hypoxia", or the "second gas effect", is a factor that influences the pO2 (partial pressure of oxygen) within the pulmonary alveoli. When water-soluble gases such as anesthetic agen ...
*
Nitrous oxide fuel blend Nitrous oxide fuel blend propellants are a class of liquid rocket propellants that were intended in the early 2010s to be able to replace hydrazine as the standard storable rocket propellent in some applications. In nitrous-oxide fuel blends, ...


References


External links


Occupational Safety and Health Guideline for Nitrous Oxide

Paul Crutzen Interview
Freeview video of Paul Crutzen Nobel Laureate for his work on decomposition of ozone talking to Harry Kroto Nobel Laureate by the Vega Science Trust.

* ttps://www.cdc.gov/niosh/topics/nitrousoxide/ National Institute for Occupational Safety and Health – Nitrous Oxide
CDC – NIOSH Pocket Guide to Chemical Hazards – Nitrous Oxide

Nitrous Oxide FAQ

Erowid article on Nitrous Oxide

Nitrous oxide fingered as monster ozone slayer
Science News
Dental Fear Central article on the use of nitrous oxide in dentistry

Altered States Database
{{DEFAULTSORT:Nitrous Oxide 5-HT3 antagonists Aerosol propellants Dissociative drugs E-number additives Euphoriants GABAA receptor positive allosteric modulators Gaseous signaling molecules General anesthetics Glycine receptor agonists Greenhouse gases Industrial gases Industrial hygiene Inhalants Nitrogen oxides Monopropellants Nicotinic antagonists Nitrogen cycle NMDA receptor antagonists Rocket oxidizers Trace gases World Health Organization essential medicines Neurotoxins