As an example of the 1000+ gases that are detectable with the WatchGas detectors, we have featured some of the most important and detected gases below.
Acetylene (C2H2) – also known as Ethyne – is a compound from the alkynes group. This gas is oftentimes used in the chemical industry as base material in organic compounds synthesis (such as acrylate or chloroethylene). Acetylene is also used during hydrocarbon cracking process (petroleum refining) and while welding with temperatures up to 3,000°C.
Acetylene effects on health
At ambient temperature, ethyne is a colourless and theoretically odourless (when it is a pure gas). Even if this gas is not toxic, respiratory hazards may lead to suffocation. It is extremely flammable (R12) and features risks of explosion (R5) with or without air contact (R6). It basically reacts with almost any oxidizer and can compose toxic and/or corrosive gas mixtures even at low concentrations.
| CAS Number | 74-86-2 |
| Gas Formule | C2H2 |
| Conversion (1ppm) | 1.06mg/m3 |
| Density | 0.9 |
| EC Number | 200-816-9 |
| UN/NA Number | |
| UN, GHS |   |
| TWA, STEL | |
| LEL, UE | 2.0% - 100% |
| IP | 11.4 |
Ammonia (NH3) – or hydrogen nitride – is industrially synthetized from nitrogen (N) and hydrogen (H2) using a catalyst (Haber-Bosch process). This substance is a key element for producing fertilizers and is used in the cooling industry. When dissolved into water, ammonia is used to produce household products. it is also exploited in the textile industry and for many other applications.
Ammonia effects on health
Above all ammonia is toxic (even at low concentrations) and very irritating to the eyes and breathing tracts. It can be easily detectable through smell with its pungent and asphyxiating smell. This gas is also flammable and explosive between 15 and 28% volume. If it enters in contact with other substances like halogens, mercury or acetaldehyde, explosive reactions can occur.
| CAS Number | 7664-41-7 |
| Gas Formule | NH3 |
| Conversion (1ppm) | 0.7 mg/m3 |
| Density | 0.59 |
| EC Number | 231-635-3 |
| UN/NA Number | |
| UN, GHS |    |
| TWA, STEL | 25ppm – 35ppm |
| LEL, UE | 15% - 28% |
| IP | 10.18 |
Historically known for being used during the First World War as a chemical weapon, arsine (AsH3) – also known as arsenic trihydride – is present in many industrial processes. It is notably used in the steel industry in ferrous metal foundries (desulfurization systems cleaning), tin foundries, metal treatment, electronics sector and boiler descaling).
Arsine effects on health
Colorless at ambient temperature, arsine (AsH3) is odorless at a nascent state. Once in contact with air, it oxidizes and gets a pronounced garlic smell. As it is heavier than air, it penetrates organisms through the breathing tracts. Arsine is highly toxic when inhaled (R26) and harmful for the aquatic environment as it easily dissolves into the water. Extremely flammable (R12), it can compose explosive mixtures between 5.1 and 78% volume.
| CAS Number | 7784-42-1 |
| Gas Formule | AsH3 |
| Conversion (1ppm) | 3.2 mg/m3 |
| Density | 2.7 |
| EC Number | 232-066-3 |
| UN/NA Number | |
| UN, GHS |  |
| TWA, STEL | - 0.002 mg/m3 |
| LEL, UE | 5.1% - 78% |
| IP | 9.89 |
Benzene (C6H6) is a volatile organic compound from monocyclic aromatic hydrocarbons. It composes fuels at 1%, particularly unleaded gasoline. It is also applied in other sectors like perfumeries as a solvent or in chemical industries as a synthesis intermediate for a large range of chemical products (rubber, solvent, food additives).
Benzene effects on health
The International Agency for Research on Cancer classified benzene as a category 1 carcinogenic agent (R45/49). This substance may also cause heritable genetic damage (R46). When ingested or inhaled, this organic compound is harmful to the breathing tracts – particularly dangerous for lungs (R65) but also for the eyes (R36) as well. In case of prolonged exposure, ingestion, inhalation or contact with the skin, benzene can lead to severe consequences on health (R48/23/24/25).
| CAS Number | 71-43-2 |
| Gas Formule | C6H6 |
| Conversion (1ppm) | 3.25mg/m3 |
| Density | 2.7 |
| EC Number | 200-753-7 |
| UN/NA Number | |
| UN, GHS |  |
| TWA, STEL | 1ppm – 5ppm |
| LEL, UE | 1.2% - 8.0% |
| IP | 9.24 |
Butane (C4H10) is an alkane hydrocarbon. This gas is produced while refining crude petroleum or in natural gas deposits. It is mainly used filled in cylinders as a household fuel (water heater, cooker, heating). However butane is used in industrial environments as well, particularly in the synthesis process of ethylene, propylene or butadiene.
Butane effects on health
If inhaled, butane can have severe consequences on human health that can lead to death (asphyxia, ventricular fibrillation). Butane combustion can also lead to these hazards as it exhausts harmful substances like nitrogen dioxide. When combustion is incomplete – because of an oxygen deficiency – butane combustion produces carbon and carbon monoxide as well.
When its concentration reaches 17,000 ppm, butane is a central nervous system depressant. At high levels, it acts like a simple asphyxiating agent that can move the necessary to breathing oxygen. It is also dangerous in confined spaces where its concentration has to stay under 10% of the LEL (lower explosive limit) – 1,600 ppm.
Butane is slightly soluble into water but dissolves into alcohol and ether. Odourless and colourless, it is gaseous at room temperature but can liquefy at relatively low pressure levels. Butane is highly flammable. It easily ignites in presence of static electricity, flame or any other ignition source. Between 1.6 and 8.4%, it forms an explosive mixture with air.
| CAS Number | 106-97-8 |
| Gas Formule | C4H10 |
| Conversion (1ppm) | 2.38mg/m3 |
| Density | 2.01 |
| EC Number | 203-448-7 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 800ppm |
| LEL, UE | 1.6% - 8.4% |
| IP | 10.63 |
Carbon dioxide (CO2) is naturally present in the atmosphere at low concentrations. Essential for photosynthesis, it can be found in greenhouses to enhance plant growth. CO2 is widely used under its different states: as a cooling block when solid, in brewery and wine growing industries when gaseous and for firefighting under its liquid state.
CARBON DIOXIDE EFFECTS ON HEALTH
Carbon dioxide (CO2) is odorless and colorless. It is involved in the greenhouse effect phenomenon as is absorbs infrared spectrum. This gas is neither toxic, nor explosive and its major hazard remains its asphyxiating properties. Heavier than air, it replaces oxygen in confined spaces or poorly ventilated areas. Moreover, as it is not detectable without proper equipment, this gas is highly dangerous for health. At concentrations of 7% to 10% death may occur from asphyxiation even if sufficient Oxygen is present.
| CAS Number | 124-38-9 |
| Gas Formule | CO2 |
| Conversion (1ppm) | 1.8 mg/m3 |
| Density | 1.53 |
| EC Number | 247-096-2 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 5.000 ppm – 30.000ppm |
| LEL, UE | |
| IP | 13.77 |
Carbon monoxide (CO) is a colourless, odourless, and tasteless flammable gas that is slightly less dense than air. It is toxic to animals that use hemoglobin as an oxygen carrier (both invertebrate and vertebrate) when encountered in concentrations above about 35 ppm, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal biological functions. In the atmosphere, it is spatially variable and short-lived, having a role in the formation of ground-level ozone.
The most common symptoms of CO poisoning are headache, dizziness, weakness, upset stomach, vomiting, chest pain, and confusion. CO symptoms are often described as “flu-like.” If you breathe in a lot of CO it can make you pass out or kill you. People who are sleeping or drunk can die from CO poisoning before they have symptoms.
Carbon monoxide is produced when fuels such as gas, oil, coal and wood do not burn fully. Burning charcoal, running cars and the smoke from cigarettes also produce carbon monoxide gas. Gas, oil, coal and wood are sources of fuel used in many household appliances, including:
| CAS Number | 630-08-0 |
| Gas Formule | CO |
| Conversion (1ppm) | 1.114 mg/m3 |
| Density | 0.968 |
| EC Number | 211-128-3 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 35ppm - |
| LEL, UE | 12.5% - 74% |
| IP | 14.01 |
Chlorine dioxide (ClO2) is exclusively an anthropogenic gas. This means that it cannot be found naturally. This synthesis produce is widely used in bleaching processes for paper pulp, flour, textile and leather cleaning. It can also be applied for its biocide and disinfecting properties for many other applications like wastewater treatment, and is used in the pharmaceutical and food industries.
Chlorine dioxide effects on health
Chlorine dioxide (ClO2) taint varies from red-orange to green-orange. Its fragrance is irritating and smells like chlorine compounds. Non-explosive in the dark, it becomes unstable with light and can produce explosive mixture under the sunlight or with fast heating (R5). Very toxic by inhalation, it can cause severe burnings (R34). Soluble into water, it can form hydrochloric acid, which is very corrosive and harmful to aquatic organisms (R50).
| CAS Number | 10049-04-4 |
| Gas Formule | ClO2 |
| Conversion (1ppm) | 2.77 mg/m3 |
| Density | 2.3 |
| EC Number | 233-162-8 |
| UN/NA Number | |
| UN, GHS |  |
| TWA, STEL | 0.1ppm – 0.3ppm |
| LEL, UE | 10% - |
| IP | 10.33 |
Historically known for being used during the First World War as a chemical weapon (mustard gas), chlorine (Cl2) is widely used for its disinfectant properties as a biocide (to remove bacteria) during the water purification process. It is also used in other sectors like the chemical industry, textile and paper industries.
Chlorine effects on health
Chlorine (Cl2) is a yellow-green gas with a particularly pungent and suffocating smell. This extremely toxic gas (R23) is irritant to the skin (R38), eyes (R36) and respiratory system (R37). As it particularly reacts with water, it may form hydrochloric acid (HCl) or hypochlorous acid (HOCl) that are extremely harmful to human health and environment.
| CAS Number | 7782-50-5 |
| Gas Formule | Cl2 |
| Conversion (1ppm) | 2.9 mg/m3 |
| Density | 2.49 |
| EC Number | 231-959-5 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 0.5ppm – 1ppm |
| LEL, UE | |
| IP | 11.48 |
Sugar fermentation into ethanol (C2H6O) – also known as ethylic alcohol or alcohol – is one of the oldest biotechnologies used to produce alcoholic beverages. It is used as a solvent or disinfectant in industries and as a raw material to produce many compounds. If concentrated and hydrated, ethanol becomes bioethanol – a biofuel (European E85) – that is mixed with gasoline or diesel.
Ethanol effects on health
Ethanol (C2H6O) is a colourless volatile liquid with a sweet smell detectable from 84 ppm. It can easily be inhaled or absorbed through skin. Intoxication acute symptoms by ingestion are well-known and essentially neuropsychic: intellectual and physical excitation, coordination deficiency then alcohol coma and even respiratory paralysis.
| CAS Number | 64-17-5 |
| Gas Formule | C2H6O |
| Conversion (1ppm) | 1.91 mg/m3 |
| Density | 1.59 |
| EC Number | 200-578-6 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 1000ppm – 1000ppm |
| LEL, UE | 3.3% - 19% |
| IP | 10.43 |
Ethylene oxide (C2H4O) – also known as ETO – was massively used during the First World War to produce refrigerant fluid and poison gas. Nowadays it is essentially synthetized and used as a raw material by the chemical industry (antifreeze and polyester resin) or exploited for its disinfectant properties in the pharmaceutical, food and textile industries.
Ethylene Oxide effects on health
Ethylene oxide (ETO) is a colorless gas with a sweet apple smell. This gas is toxic by inhalation (R23) or in contact with the skin, eyes and breathing system (R36/37/38). The IARC* noticed a link between exposure to ETO and some kinds of cancer (R45) or inheritable genetic damages (R46) in case of chronic exposure. As it is flammable (R12), it can form explosive gaseous mixtures with or without contact with air (R6).
| CAS Number | 75-21-8 |
| Gas Formule | C2H4O (ETO) |
| Conversion (1ppm) | 1.83 mg/m3 |
| Density | 1.49 |
| EC Number | 200-849-9 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 1ppm |
| LEL, UE | 3% - 100% |
| IP | 10.56 |
Formaldehyde (CH2O) – also known as methyl aldehyde, methanol or formol – is naturally present in incomplete combustion with carbon (forest fires, thermal engines, tobacco smoke). This gas is used for many applications like in agriculture, wood industry, building construction, food industry or pharmaceutical sector.
Formaldehyde effects on health
Formaldehyde (CH2O) is a colourless gas with a pungent and suffocating smell. This gas is very toxic by inhalation (R23), in contact with skin (R24), or if swallowed (R25) and can cause burns (R34). Featuring explosive limits between 7 and 73% volume, this gas is flammable and explosive. It can form explosive mixtures or enhance the explosive potential of other mixtures. The IARC exposed a link between formaldehyde vapor explosivity and carcinogenic effects (R40).
| CAS Number | 50-00-0 |
| Gas Formule | CH2O |
| Conversion (1ppm) | 1.23 mg/m3 |
| Density | 1.04 |
| EC Number | 200-001-8 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 0.75ppm – 2ppm |
| LEL, UE | 7% - 73% |
| IP | 10.88 |
Hydrogen chloride (HCl) – also known as hydrochloric acid under its liquid state – is a natural gas exhausted during volcanic eruptions. This gas is even present in the human body at very low concentrations to give stomach its pH acid. HCl hazards are present in many sectors as this substance is widely used as a base product in the chemical industry, pharmaceutical industry, oil wells and steel production.
Hydrogen chloride effects on health
In its gaseous state, hydrogen chloride is a colourless substance with a pungent and irritant fragrance. Very soluble into water, its reaction releases high heat and hydrogen – a highly explosive gas. Very toxic by inhalation (R23), hydrogen chloride is very corrosive too and causes severe burnings (R35) when in contact with the skin and may seriously damage the eyes.
| CAS Number | 7647-01-0 |
| Gas Formule | HCl |
| Conversion (1ppm) | 1.49 mg/m3 |
| Density | 1.268 |
| EC Number | 231-595-7 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 5ppm – 10ppm |
| LEL, UE | |
| IP | 12.74 |
Hydrogen cyanide (HCN) – also called hydrocyanic acid or formonitrile – is a chemical compound that can be found in either liquid or gaseous form. Widely used as an insecticide, it is also applied for fumigation applications in the chemical industry. It can be accidentally produced during chemical reactions between cyanide and an acid, or through fire and nitriles combustion.
Hydrogen cyanide effects on health
With variant colour from colourless to pale blue, hydrogen cyanide (HCN) is easily detectable through its bitter almond smell. This highly toxic gas features many harmful or lethal properties. With explosive limits between 5.6 and 40%, this chemical compound is extremely flammable.
| CAS Number | 74-90-8 |
| Gas Formule | HCN |
| Conversion (1ppm) | 1.1 mg/m3 |
| Density | 0.94 |
| EC Number | 200-821-6 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 10ppm – 4.7ppm |
| LEL, UE | 5.6% - 40% |
| IP | 13.6 |
Hydrogen fluoride (HF) – also known as hydrofluoric acid – can be found in its gaseous form or under its liquid state at ambient temperature. It is mainly used in the petrochemical industry as an alkylation catalyst but also in the pharmaceutical industry (pharmaceutical products synthesis), on construction sites (building facade cleaning) and in surface treatment (pickling) or uranium treatment.
Hydrogen fluoride effects on health
Hydrogen fluoride (HF) is a colourless gas featuring a pungent smell. This gas is very toxic by inhalation (R26), if swallowed (R28) or in contact with the skin (R27). It reacts with water to form hydrofluoric acid, which is very corrosive and extremely dangerous for the environment – it changes water pH. Even if this gas is not flammable, it reacts with almost any metal in presence of humidity and produce hydrogen (H2) – and highly flammable gas.
| CAS Number | 7664-39-3 |
| Gas Formule | HF |
| Conversion (1ppm) | 0.82 mg/m3 |
| Density | 0.7 |
| EC Number | 231-634-8 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 3ppm – 6ppm |
| LEL, UE | |
| IP | 15.98 |
Hydrogen peroxide (H2O2) – also known as oxygenated water – is a gas widely used as a bleaching agent in paper plants and the textile industry. Because of its disinfectant properties, this gas is used in laboratories to sterilize, in the food industry to disinfect packaging and in the pharmaceutical industry to sanitize contact lens or to produce bactericidal products.
Hydrogen peroxide effects on health
Hydrogen peroxide is most commonly known under its liquid state – oxygenated water. Whether liquid or gaseous, this substance is colourless and odourless. H2O2 is corrosive and harmful by inhalation or if swallowed and might cause severe burns. Although this gas features no explosive limits, heating may cause an explosion and its contact with combustible material may cause fire.
| CAS Number | 7722-84-1 |
| Gas Formule | H2O2 |
| Conversion (1ppm) | 1.39 mg/m3 |
| Density | 1.17 |
| EC Number | 231-765-0 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 1ppm - |
| LEL, UE | |
| IP | 10.54 |
Hydrogen sulphide (H2S) is a colourless gas with a characteristic odour of rotten eggs which being denser than air may pool in low areas in still conditions.
People are normally exposed to hydrogen sulphide in air by breathing it in or by skin/eye contact. Any absorbed hydrogen sulphide does not accumulate in the body as it is rapidly metabolised in the liver and excreted in the urine. Hydrogen sulphide usually breaks down in air in about 3 days and is dispersed by wind.
If the smell of hydrogen sulphide is strong or you are concerned about its impacts on your amenity or health, you can reduce your exposure by:
| CAS Number | 7783-06-4 |
| Gas Formule | H2S |
| Conversion (1ppm) | 1.4 mg/m3 |
| Density | 1.19 |
| EC Number | 231-977-3 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 1ppm – 5ppm |
| LEL, UE | 4% - 46% |
| IP | 10.49 |
Industrially produced by reforming hydrocarbons – natural gas steam reforming – hydrogen (H2) – also called dihydrogen – is mainly used to remove sulfur from petroleum fuels and to produce ammonia. It is also considered as the fuel of the future (fuel cells). It is primarily released while charging batteries or during welding.
Hydrogen Gas Hazards
Hydrogen (H2) is extremely flammable (R12) with wide explosive limits between 4 and 75% volume. As it is particularly lightweight, major hydrogen gas hazards are the replacement of oxygen in suspended ceilings and other high up confined spaces. Colorless and odorless, its presence cannot be detected without proper equipment. Even if it is not toxic, high concentrations of hydrogen will reduce the oxygen rate, which can lead to asphyxia. For all these reasons it is important to use an hydrogen monitor to detect dangerous concentrations
| CAS Number | 1333-74-0 |
| Gas Formule | H2 |
| Conversion (1ppm) | 0.083 mg/m3 |
| Density | 0.07 |
| EC Number | 215-605-7 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | |
| LEL, UE | 4% - 75% |
| IP | 15.43 |
Natural gas – or methane – (CH4) is naturally produced from decomposition of organic matter in poorly oxygenated areas. Its anthropogenic version is massively produced through the exploitation and combustion of fossil matter and in any other field of activity with organic matter decomposition: waste landfill sites, biogas production.
Dangers of methane gas
Methane (CH4) is colourless, odourless and heavier than air. Because of these properties, this gas cannot be detected without proper equipment and can accumulate in suspended ceilings and other high-up areas. This gas is above all extremely flammable (R12) and explosive, with explosive limits between 5 and 15% volume.
Methane – CH4 gas – is not a toxic gas but it might replace oxygen when reaching high concentration levels in poorly ventilated areas. It is also responsible of the greenhouse effect as it absorbs earth infrared rays that enhance climate warming. Methane is one of the six major gases covered by the Kyoto protocol.
| CAS Number | 74-82-8 |
| Gas Formule | CH4 |
| Conversion (1ppm) | 0.66 mg/m3 |
| Density | 0.6 |
| EC Number | 200-812-7 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | |
| LEL, UE | 5% - 15.4% |
| IP | 12.51 |
Nitrogen dioxide (NO2) is considered responsible for atmospheric pollution. As a consequence, this gas is a major indicator for air quality monitoring agencies. It is notably produced during the internal combustion of diesel-powered engines and can be found in any area with these vehicles (mines, garages, car parks…). NO2 is also widely used in the chemical industry for example for nitric acid (HNO3) synthesis.
Nitrogen Dioxide Effects on health.
Nitrogen dioxide is a yellow-brown gas with a pungent smell from 0.2 ppm. This gas is irritating to the eyes (R36) and respiratory system (R37). It is very toxic by inhalation (R26) as well and can cause burns (R34). Non-flammable and non-explosive, nitrogen dioxide is a strong oxidizer that can ignite combustion. Its reactivity with many chemical compounds (chloride compounds, benzene) can produce explosive gaseous mixtures.
| CAS Number | 10102-44-0 |
| Gas Formule | NO2 |
| Conversion (1ppm) | 1.88 mg/m3 |
| Density | 1.59 |
| EC Number | 233-272-6 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 1ppm |
| LEL, UE | |
| IP | 9.58 |
Nitrogen oxide (NO) – also known as nitric oxide – is an anthropogenic gas released by contact between nitric acid and many compounds. It can be found in many industries like wood (sawdust), explosives (dynamite), metals (engraving) and in high heat welding applications. This gas – which is partially responsible for atmospheric pollution – is exhausted by diesel-powered engines; that’s why it is present in underground parking garages.
Nitrogen oxide is a colourless gas featuring a sweet smell that can be pungent starting at 0.3 ppm. As it is slightly soluble into water, it reacts with water molecules to form nitric acid, which is very corrosive. In case of chronic exposure, this gas can have irreversible effects (poison gas); it is also very toxic by inhalation (R26) and might cause chemical burns (R34).
| CAS Number | 10102-43-9 |
| Gas Formule | NO |
| Conversion (1ppm) | 1.2mg/m3 |
| Density | 1.04 |
| EC Number | 213-598-5 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 25ppm - |
| LEL, UE | |
| IP | 9.26 |
Nitrous oxide, commonly known as laughing gas, nitrous, dinitrogen oxide or dinitrogen monoxide, is a chemical compound, an oxide of nitrogen with the formula N2O. At elevated temperatures, nitrous oxide is a powerful oxidizer like molecular oxygen.
Nitrous oxide has significant medical uses, especially in surgery and dentistry, for its anesthetic and pain-reducing effects. Its colloquial name "laughing gas", coined by Humphry Davy, is due to the euphoric effects upon inhaling it, a property that has led to its recreational use as a dissociative anesthetic. This is not without dangers. It depletes the vitamin B12 in the body of the user, leads to irreversible brain damage, and excessive use can even lead to spinal cord injury.
It is on the World Health Organisation's List of Essential Medicines, the safest and most effective medicines needed in a health system. It is also used as an oxidizer in rocket propellants, and in motor racing to increase the power output of engines.
| CAS Number | 10024-97-2 |
| Gas Formule | N2O |
| Conversion (1ppm) | |
| Density | 1.53 |
| EC Number | 233-032-0 |
| UN/NA Number | 1070 |
| UN, GHS | |
| TWA, STEL | |
| LEL, UE | |
| IP | 12.89 |
Oxygen (O2) – which is most commonly known as oxygen – is a gas naturally present in the atmosphere at around 20%. It is essential to almost any form of life on Earth. This highly reactive gas can easily produce compounds (particularly oxides) from elements except for noble gases like helium or neon.
Oxygen effects on health
Oxygen (O2) is a colourless, odourless and tasteless gas that composes breathing air at 10.9%. In contrast to the great majority of gases, the lower the oxygen concentration is, the higher are the risks for health. In the medicine field, oxygen is inhaled primarily in case of asphyxia, intoxication to carbon monoxide, or to treat acute pulmonary edema. This gas is not measured in ppm but in % volume.
| CAS Number | 7782-44-7 |
| Gas Formule | O2 |
| Conversion (1ppm) | 1.31 mg/m3 |
| Density | 1.43 |
| EC Number | 231-956-9 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | |
| LEL, UE | |
| IP | 12.1 |
Naturally present in the atmosphere, trioxygen (O3) – most commonly known as ozone – is naturally released by nitrogen oxides (NOx). Ozone is also industrially produced through electrical shocks in tubular generators. It is used for wastewater treatment (water ionization) but also for printing works (laser radiation) and arc welding with inert gases.
Ozone effects on health
Ozone (O3) taint varies from colourless to blue with a bleach-like pungent smell, detectable from 0.01 ppm. Non-flammable, ozone is a strong oxidizer and can ignite explosions. Although its toxicity depends on several factors (temperature, pressure, concentration), ozone is very harmful for the breathing system (lungs, nose, throat) and can irritate the eyes.
| CAS Number | 10028-15-6 |
| Gas Formule | O3 |
| Conversion (1ppm) | 2 mg/m3 |
| Density | 1.66 |
| EC Number | 233-069-2 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 0.1ppm - |
| LEL, UE | |
| IP | 12.43 |
Pentane (C5H12) is relatively inexpensive. This gas is one of the most volatile liquid alkane at ambient temperature. Thus it is oftentimes used in laboratories as a solvent that can evaporate quickly and easily. It is a blowing agent as well used to produce polystyrene foam and other foams. Pentane can also be added to some refrigerant systems (-80°C lockers e.g.) as a refrigerant fluid additive.
Pentane effects on health
Under its liquid state, pentane (C5H12) is a colourless liquid, with low viscosity and a specific smell. Its effects on health depends on inhaled concentrations. The first effect is euphoria, then headache at higher concentrations, tinnitus and nausea. At very high concentration levels, incoordination, confusion signs or even convulsive coma may occur.
| CAS Number | 109-66-0 |
| Gas Formule | C5H12 |
| Conversion (1ppm) | 2.95mg/m3 |
| Density | 2.49 |
| EC Number | 203-692-4 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 120ppm |
| LEL, UE | 1.5% - 7.8% |
| IP | 10.34 |
Carbon dichloride oxide (COCl2) – most commonly known as phosgene – is synthesized through a reaction between carbon monoxide and chlorine. It can also be released during chlorinated hydrocarbon vapor decomposition of plastics pyrolysis. It can be found in the chemical industry – herbicide and insecticide synthesis – and during the production of pharmaceutical products, dye and chlorination agents. It was being used as a chemical warfare agent during World War I and can still be encountered by farmers in the soil in the North of France.
Phosgene effects on health
As phosgene (COCl2) is extremely toxic, it has been used as a chemical weapon and a poison gas during the First World War. This gas is very toxic by inhalation (R26) and causes chemical burns (R34). At ambient temperature, this gas is colorless or sometimes slightly yellowish with a decomposition smell – moldy hay or rotten apple.
| CAS Number | 75-44-5 |
| Gas Formule | COCl2 |
| Conversion (1ppm) | 4.05 mg/m3 |
| Density | 3.4 |
| EC Number | 200-870-3 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 0.1 ppm (0.4 mg/m3) - 0.2 ppm (0.8 mg/m3) |
| LEL, UE | |
| IP | 11.55 |
Phosphorus trihydride (PH3) – most commonly known as phosphine – is mainly used for fumigation applications because of its biocide properties – required for international transport. Phosphine is also industrially released while producing acetylene, during metals de-rusting process with phosphoric acid or in metal treatment plants with phosphides.
Phosphine gas effects on health
Phosphine is a colorless gas that can be detected through its fishy smell. This gas is very toxic by inhalation (R26) and can cause chemical burns (R34). This substance is very harmful for the environment, especially for aquatic organisms (R50). It is extremely flammable (R12) when in contact with oxidizers, halogenated hydrocarbons, aluminum or copper; and explosive – spontaneously flammable in the air (R17).
| CAS Number | 7803-51-2 |
| Gas Formule | PH3 |
| Conversion (1ppm) | 1.41 mg/m3 |
| Density | 1.18 |
| EC Number | 232-260-8 |
| UN/NA Number | 2199 |
| UN, GHS | |
| TWA, STEL | 0.1ppm – 0.2ppm |
| LEL, UE | 1.6% - 98% |
| IP | 9.96 |
Propane (C3H8) or dimethyl methane is an alkane that is mainly used as a combustion energy source in internal combustion engines or boilers. It is primarily released from natural gas purification or liquefied petroleum gases separation. Propane is industrially used as a reactive agent for synthesis of ethylene, benzene, toluene or xylene.
Propane effects on health
When pure, propane (C3H8) is a colourless and odourless gas. Ethanethiol – an odorant – is added to easily detect any gas leak. Propane is harmful by inhalation and causes oxygen depletion. It can be found gaseous at ambient temperature but it also can liquefy under a pressure around 10 bars. Its combustion is clean and generates water and carbonic gas.
| CAS Number | 74-98-6 |
| Gas Formule | C3H8 |
| Conversion (1ppm) | 1.8 mg/m3 |
| Density | 1.55 |
| EC Number | 200-829-9 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 1000ppm |
| LEL, UE | 2.1% - 9.5% |
| IP | 11.07 |
Silicon tetrahydride (SiH4) – most commonly known as silane, monosilane, silicane – is an active gas primarily used for deposing silicon base layers. This process is performed through pyrolysis in the glass industry: oxygen-free thermal decomposition of organic materials. It is also used to produce amorphous silicon for photocopiers or solar cells.
Silane effects on health
At ambient temperature, silane (SiH4) is a colorless gas with a specific smell. As it is heavier than air, it can replace oxygen in poorly ventilated areas and create asphyxiating environments. The major silane hazard remains its explosiveness. Indeed, as it is extremely flammable, it can spontaneously ignite when in contact with the air. If heated, it produces hydrogenated silicon, which increase the risk of explosion.
Silane can be swallowed by inhalation. If released, this gas can swiftly reach hazardous concentration levels in the air. If inhaled, silane causes headaches, nausea, coughing and sore throat. The liquid’s fast evaporation can cause frostbite.
| CAS Number | 7802-62-5 |
| Gas Formule | SiH4 |
| Conversion (1ppm) | 1.31 mg/m3 |
| Density | 1.2 |
| EC Number | 232-263-4 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 5 ppm (7 mg/m3) |
| LEL, UE | 1.37% - 100% |
| IP | 11.00 |
Styrene (C8H8) is used to produce plastics like polystyrene. In reaction with other monomers such as acrylonitrile and/or butadiene, it is used to synthetize rubber or latex. The pharmaceutical industry and perfumeries are using small quantities of styrene as an additive in perfumes and medicine. This substance is also used in the chemical industry as a solvent to synthetize polyester resins.
Styrene effects on health
Styrene (C8H8) is a colourless or sometimes yellowish gas with a soft smell detectable from 0.15 ppm. This volatile organic compound is very harmful by inhalation and can cause irritation to the skin and eyes (R36/38). As it is flammable between 0.9 % and 6.8 % volume, styrene vapours can form explosive gaseous mixtures. It also features reprotoxic effects. The International Agency for Research on Cancer classified it as possibly carcinogenic to humans (Group 2B).
| CAS Number | 100-42-5 |
| Gas Formule | C8H8 |
| Conversion (1ppm) | 4.26mg/m3 |
| Density | 3.6 |
| EC Number | 202-851-5 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 50ppm – 100ppm |
| LEL, UE | 0.9% - 6.8% |
| IP | 8.4 |
Sulphur dioxide (SO2) – also called sulphurous anhydride – is present in many fields of activity such as the pulp and paper industry, power plants, the cooling industry and fossil energy combustion (coal and fuel). It is also used for wine growing application. Even if it can be naturally found near volcanoes, this gas is essentially anthropogenic.
Sulphur dioxide effects on health
Sulphur dioxide (SO2) is a colourless gas with a pungent fragrance that may cause breathing system and eyes irritation starting at 1 ppm! Even if it is corrosive and harmful, this gas is above all toxic. It has been classified as R23 (toxic by inhalation) and R34 (causes burns). Lastly, sulphur dioxide is very reactive with many solvents (alcohol, toluene), and particularly with water to produce sulfuric acid (H2SO4). SO2 is also responsible for acid rain.
| CAS Number | 7446-09-5 |
| Gas Formule | SO2 |
| Conversion (1ppm) | 2.62 mg/m3 |
| Density | 2.26 |
| EC Number | 231-195-2 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 2ppm – 5ppm |
| LEL, UE | |
| IP | 12.3 |
Heavily produced during the Second World War to produce TNT, methyl benzene (C7H8) – or toluene – is a volatile organic compound. This substance is now used in many fields of activities such as construction sites (paint solvent, glue or polish), printing plants (ink) or the pharmaceutical industry. It can also be found in some petroleum products to enhance the octane rating in fuels.
Toluene effects on health
Featuring a specific smell (dissolvent), toluene (C7H8) is a colourless, flammable and explosive gas. It reacts with many volatile organic compounds and oxidizers to produce even more explosive gaseous mixtures. This gas is also very harmful and even lethal if swallowed or absorbed by the breathing tracts. Chronic exposure can lead to severe effects to vital organs and can impair fetus health in pregnant women.
| CAS Number | 108-88-3 |
| Gas Formule | C7H8 |
| Conversion (1ppm) | 3.83mg/m3 |
| Density | 3.14 |
| EC Number | 203-625-9 |
| UN/NA Number | |
| UN, GHS | |
| TWA, STEL | 100ppm – 150ppm |
| LEL, UE | 1.2% - 7.1% |
| IP | 8.82 |
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