GASTEC CORPORATION - For all types of gas and vapour

Properties of gas

Carbon monoxide (CO)


What kind of substance is carbon monoxide?


A colourless, odourless, highly toxic gas that is formed whenever incomplete combustion of carbon, or carbon-containing compounds occurs. In our immediate environment it frequently is given off by industrial gas burners, and as it can be found in automotive exhaust or cigarette smoke it tends to accumulate in poorly ventilated places like congested road tunnels or bars at levels approaching or even exceeding the 50ppm threshold.


What are the symptoms that carbon monoxide has been inhaled?


CO depletes the oxygen in the blood hemoglobin leading to such typical symptoms as headaches, nausea, dizziness, etc.

Toxicity index
(CO concentration x exposure time)
≤300 No discernible effects
600 A slight effect (drowsiness, queasiness)
900 Headaches, nausea
≥1500 Potentially lethal

Where is carbon monoxide measurement mainly conducted?


Primarily factory facilities equipped with furnaces or other combustion equipment, or any location requiring ambient/atmospheric air pollution monitoring; for instance, where industrial or vehicle emissions occur, as well as anywhere that occupational/industrial or residential hygiene is at issue (office buildings, theatres, concert halls, etc.).

Hydrogen sulphide


What kind of substance is hydrogen sulphide?


H2S is a colourless, toxic, flammable gas that occurs naturally in volcanic vapours, hot springs; and it often is generated through the hydrolysis of sulphide salts especially where bacteria break down organic matter in the absence of oxygen, e.g. in swamps, sewers, rivers, harbours, etc. It also occurs as a manmade by-product in such industrial facilities as chemical plants, paper mills, oil refineries, etc.


What are the symptoms that hydrogen sulphide has been inhaled?


H2S is absorbed into the bloodstream, and transmitted to the nervous system via the lungs, Low concentrations are oxidised in the blood and quickly become harmless; high concentrations have a sweetish aroma and a neurotoxic effect, irritating the mucous membranes in the nose, throat, eyes; may cause subacute poisoning or affect the olfactory nerve to the point of losing one's sense of smell. Basically, hydrogen sulphide is one of the more common pungent odour-emitting and discomfort-causing substances.

Hydrogen sulphide
0.03 The recognition threshold (that can be perceived by smell)
50 Gives off an unpleasant smell
50-100 Respiratory tract irritation, conjunctivitis
100-200 Olfactory paralysis (loss of sense of smell)
200-300 Subacute poisoning after continuous exposure of one hour
600 Can be lethal when exposure lasts one hour
1,000-2,000 Instantly lethal

Where is hydrogen sulphide measurement mainly conducted?


At sites where staff are in potential danger of hydrogen sulphide poisoning, such as sewage treatment facilities, manhole interiors, workshop pits, chemical plants, pulp mills, petroleum refineries, and even hot spring spas where sulphur content in vapour emissions or discharge water is 2mg/kg or more.



What kind of substance is ammonia?


It is given off in the biodegrading process by microbes (in nature), and as a byproduct of seafood processing. Besides being a common synthetically produced inorganic component of nitric acid and fertiliser, it also has a broad range of other industrial uses. Since, ammonia does not harm the ozone layer, it has increasingly been coming into use as a refrigerator coolant.


What are the symptoms that ammonia has been inhaled?


Ammonia is one of the typical, malodourous substances, which cause discomfort. Inhalation of high concentrations is liable to cause pulmonary oedema. Contact with the skin or mucous membranes causes irritation that may penetrate as far as the inner tissue. When the eyes come into contact with high ammonia concentrations, visual impairment may result.

Ammonia concentration
5-10 Gives off pungent smell
50 Can cause discomfort
100 Causes slight irritation
200-300 Irritates eyes and throat
300-500 The short term endurance limit (30 - 60 min)
2,500-5,000 Life threatening after short time (30 min)
5,000-10,000 Breathing stops, lethal after short-term exposure

Where is ammonia measurement mainly conducted?


Ammonia is primarily measured in the context of occupational hygiene management, air contamination/pollution prevention, and manufacturing process control. Common measurement sites include:
Livestock farms, sewage treatment facilities, seafood processing plants, ironworks, and production facilities for: soda, melamine resin, fertiliser or refrigerants/refrigerators.

Carbon dioxide


What kind of substance is carbon dioxide (CO2)?


Generally carbon dioxide is generated during the respiratory process of animals and plants and when microbes break down organic or when carbon materials combust. It is necessary for the process of photosynthesis in plants. In recent years the amount of CO2 has been increasing, and is becoming a serious factor contributing to global warming, the "greenhouse effect".


What are the symptoms that carbon dioxide has been inhaled?


Although, it is extremely rare for weak carbon dioxide poisoning to have any ill effects, high concentrations can cause carbon dioxide narcosis, and in extreme cases even be lethal.

Carbon dioxide concentration
0.55 After six hours of exposure there are no symptoms
1-2 Light feeling of nausea may occur
3-4 Irritates respiratory center, and accelerates breathing, a rise of pulse / blood pressure, a headache, dizziness appear
6 Causes dyspnea
7-10 Can cause loss of consciousness and cyanosis; fatal if exposure lasts several minutes

Where is carbon dioxide measurement mainly conducted?


CO2 measurement is primarily conducted in order to ensure a comfortable indoor environment in all manner of common and familiar places. To protect the safety of people in offices, hotels/inns, department stores, movie theatres, classrooms, indoor swimming/bathing facilities, etc., as well as welding shop floors, tunnels, breweries, warehouses, agricultural facilities (including livestock farms); horticulture, scientific research (including experiments involving the respiration process of flora and fauna, photosynthesis in plants, combustion processes, etc.) and other fields.



What kind of substance is oxygen?


Oxygen, the most abundant naturally occurring gas, is discharged into the atmosphere through the process of plant photosynthesis. It is consumed during the respiration process of flora and fauna, photosynthesis in plants, as well as combustion processes. The oxygen content in air is about 21%, in water 88.8%, and in the human body it is about 65%.


What are the symptoms of extreme oxygen deficiency?


Not enough oxygen in the ambient air can be fatal, causing hypoxia (deprivation of an adequate oxygen supply for the body. On the other hand, excessive oxygen in the air poses a fire hazard as it lowers the combustion temperature of flammable materials, and it serves as an accelerant as well.

Symptoms of oxygen deficiency
Oxygen (%) symptoms
15-14 Breathing is deepened, and the pulse accelerates; physical exertion becomes difficult
11-10 Can cause dyspnea and drowsiness; body movement becomes sluggish.
7-6 Complexion turns pale, and senses become dull with accompanying loss of perception
max.4% Within 40 seconds, loss of perception, to the point of losing consciousness

Where is oxygen measurement mainly conducted?


Essentially, oxygen concentrations are measured in working environments to prevent hypoxia incidents; particularly sites where air often stagnates; for instance: manholes, workshop pits, storage tanks, silos, sewer pipes/conduits, warehouses, holds or galleys (on ships), etc. Typically, measurement is conducted before the day's work begins and as necessary.

Sulphur dioxide


What kind of substance is sulphur dioxide (SO2)?


Sulphur dioxide gas (sometimes also called sulphurous acid gas) has a strong pungent smell. It is produced industrially, by roasting pyrites or sulphur in the presence of air. Moreover, it occurs naturally in volcanic gas and it is a byproduct of fossil fuel (oil, coal, etc.) combustion that is a cause of air pollution.


What are the symptoms that sulphur dioxide has been inhaled?


High concentrations cause severe irritation of eyes, nose, and throat. When it dissolves in the water content of the skin, a corrosive acid (sulphurous acid) is formed. Prolonged exposure can cause glottal and pulmonary oedema seriously affecting the respiratory process.

How does it affect the human body?
Sulphur dioxide concentration
0.1-1 Has an offensive odour
2-3 Can cause an irritating odour and leave an unpleasant smell
5-10 Irritates nose and throat; may cause coughing
20 Irritates the eyes and throat; causes severe coughing
30-40 Breathing becomes difficult
50-100 Short term (30-60 min) endurance threshold
400-500 Potentially lethal, already after brief exposure

Where is sulphur dioxide measurement mainly conducted?


It is primarily measured as part of the regular 24 hr. air pollution control and monitoring conducted by various jurisdictions (alongwith oxidant / nitrogen oxide levels) at their environmental measurement stations. Furthermore, it is also frequently measured at the source of emission.



What kind of substance is formalin?


In chemistry, a 40% formaldehyde solution is called formalin. Formalin is used as a raw material for various resin compounds, for sterilization procedures, as a disinfectant, and antiseptic, etc. in biochemical laboratories. Recently, the fumes given off by phenol resin based adhesives have become a big problem.


How does it affect the human body?


In a state of solution, it irritates the skin and hardens it until it cracks, and can cause ulcers. In its gaseous state, it irritates the eyes and when inhaled, the mucous membranes, causing coughing fits. Chronic effects include hepatic (liver) and renal (kidney) disorders.


Where is formalin measurement mainly conducted?


Besides environmental measurement at various types of manufacturing facilities, measurement inside residential premises is quite common. Increasingly, measurement in ambient air and the general atmosphere is being conducted as formalin has been identified as a high-priority air contaminant requiring immediate control measures.



What kind of substance is ozone?


Ozone (O3) is actually a triatomic allotrope of oxygen: one ozone molecule contains one (radical) oxygen atom more than diatomic O2 (from which it can also be formed by action of high energy electromagnetic radiation).
Paradoxically, although the ozone layer in the atmosphere (approximate O3 concentration: 0.005ppm) protects the earth from the sun's ultraviolet light, at ground level in coastal regions (where ultraviolet light is particularly intense) 0.05ppm of ozone can be found. Because ozone is highly oxidisable, it is used for sterilization, disinfection, bleaching, and as an oxidant and such in organic synthesis.


How does it affect the human body?


When 0.1ppm of ozone are inhaled for two hours, the lung capacity can decrease by 20% or so. Headaches or bronchitis may result when a concentration of 1ppm is inhaled for six hours.
In experiments, when laboratory rats inhaled 10ppm, they suffered pulmonary oedema and died which indicates a comparable degree of toxicity as phosgene, which is widely-acknowledged as a highly toxic gas.


What are the common methods for analysing / measuring ozone?


A typical analysis method involves the use of a potassium iodide solution to absorb ozone and determine the concentration by absorptiometry. Other practical methods entail the use of instruments for measuring ultraviolet (UV) light absorption, chemiluminescence, controlled potential electrolysis (CPE), or galvanic cells.
Finally, there is the simple and easy-to-use gas-detector tube method. GASTEC detector tube (18L, 18M) for ozone gas are ideally suited for measurement in the vicinity of any potential ozone sources.



What kind of substance is methane?


Methane, a colourless and odourless gas has long been known as a chief ingredient of swamp gas. Methane gas is formed as organic matter such as cellulose decays in the mud of marshes or other wetlands. It is flammable and when mixed with air can become volatile enough to explode. It often accumulates in underground passageways/conduits (including mine shafts and sewers) where it can pose a serious explosion hazard.


How does it affect the human body?


Methane in itself is harmless, but when its concentration rises, the oxygen concentration falls which can cause hypoxia.
It also poses an explosion hazard, as it is easily ignitable; (explosive hazard range 5.0-15.0%)


Where is methane measurement mainly conducted?


As one measure to prevent explosions and hypoxia incidents it has long been conducted in coal mine shafts as well as in other underground work environments such as public works and civil engineering sites.

Nitrogen oxides


Where is nitrogen oxides measurement mainly conducted?


Nitrogen oxides (NOx) is a generic term for any of a number of different oxygen compounds (known as oxides) of nitrogen that are given off during combustion, including nitrogen monoxide (NO) and nitrogen dioxide (NO2). Today, their primary sources include automobile exhaust and factory emissions; although heating and cooking fumes do their part as well.


What kind of substance is nitrogen oxides?


One of the most common nitrogen oxides is nitrogen monoxide (NO) which most commonly is generated during high temperature combustion; however, when nitrogen monoxide is discharged into the atmosphere, it oxidises into nitrogen dioxide (NO2). When this process occurs under certain meteorological conditions where the interaction of ultraviolet light as well as the presence of hydrocarbons come into play, photochemical smog is created.
To regulate nitrogen dioxide emissions (which are inherently more toxic and hazardous than NO), a number of environmental standards are in place.


How do nitrogen oxides affect the human body?


It is extremely rare for nitrogen monoxide (NO) or nitrogen dioxide (NO2) to be present without the other. Nitrogen dioxide is toxic and, in high concentrations, strongly irritates eyes, nose, and throat, causing a cough or even pharyngalgia at times, dizziness, headaches, or nausea at times.
If a large quantity is inhaled, the lips turn blue 5-10 hours later, and cyanosis may occur in addition to pulmonary oedema. Even low concentrations generally becomes a problem and raises chronic bronchitis, gastrointestinal dysfunctions, teeth problems and sleep disturbance as chronic symptoms. In addition, it weakens the body's immune system.


Where are nitrogen oxides measurement mainly conducted?


Similar to sulphur dioxide, it is primarily measured as part of the regular 24 hr. air pollution control and monitoring conducted by various jurisdictions at their environmental measurement stations. Furthermore, it is also frequently measured at the source of industrial emissions or automobile exhaust.



What kind of substance is trichloroethylene?


Trichloroethylene is very volatile and in its liquid state at normal temperatures. It is commonly used to degrease metal machine parts and when it seeps underground it sometimes contaminates wells or groundwater which is increasingly becoming a problem in recent years.


How does it affect the human body?


It irritates eyes, nose, and throat while repeated skin contact may cause dermatitis. Headache, dizziness, nausea is caused when it absorbs water vapour and it may even cause liver damage.
In addition, nausea, diarrhea, hepatic disorders, etc. can occur if trichloroethylene is swallowed.


What kind of place is the measurement of trichloroethylene performed mainly in?


Detector tubes are primarily used to measure effluent or groundwater in the context of occupational hygiene management, water contamination/pollution research and prevention, as well as gas emission concentrations.



What kind of substance is chlorine?


Chlorine, a highly caustic gas with a strong irritating odour, does not occur naturally as such.
Chlorine-based solvents such as chloroethylene or organochlorine and inorganic chlorine compounds are widely used as source material in a broad range of products and processes including paper bleach, pulp fiber, medical supplies, pesticides, pigment dye, mineral ore refinement and metal processing. Moreover, urban drinking water which we use every day contains chlorine as a disinfectant to eliminate bacteria.


How does it affect the human body?


Inflammation is caused when chlorine comes into contact with the skin. When inhaled, causes coughing and dyspnea, and even death. Chronic symptoms include bronchitis, inflammation of nasal mucous membranes.

0.1-0.2 It gives off a foul odour
1 Has a comparatively strong, unpleasant odour
3-6 Irritating to eyes, nose, throat; liable to cause headaches
14-21 Can be fatal for exposure of 0.5-1 hour
40-60 Can already be fatal after short exposure
100 Unbearable for more than one minute
900 Instantly fatal

Where is chlorine measurement mainly conducted?


The work environment at various industrial and public venues where chlorine is regularly used; for instance, for factory emissions measurement and air pollution prevention or at water purification plants, swimming pools, etc.

Hydrogen cyanide


What kind of substance is hydrogen cyanide?


Also known as hydrocyanic or prussic acid, hydrogen cyanide is a clear colourless gas with a faintly bitter almond-like odour that is volatile in its liquid state with a boiling point of 25.7ºC (78.26ºF) and a ignition point of 17.8ºC (64ºF). It is soluble in water and often used as an aqueous solution. Its vapour density is slightly less than air (0.947) and its LEL (lower explosion limit) is 5.6% and its UEL (upper explosion limit) is 40%.
It is chiefly used as a source material for various organic compounds such as acrylonitrile, or for potassium cyanide as well as in insecticides/pesticides, etc.


How does it affect the human body?


Hydrogen cyanide (HCN) is one of the most lethal poisons, being twice as toxic as potassium cyanide. It can be fatal not only when swallowed, but, even when it merely comes into contact with the skin. Characteristic of hydrogen cyanide poisoning is how quick it acts. It takes between a few seconds and 30 minutes maximum for a fatal dose (300ppm or more) to kill an adult. Hence, any emergency first aid (detox) measures must be immediately and swiftly initiated or it will be too late.
When the gas is inhaled it may cause headaches, dizziness, ringing in the ears, or vomiting and in severe cases, unconsciousness, or even death.

The concentration and an illustration of action
(In the case of gas inhalation)
Hydrogen cyanide
18-36 Only slight discomfort after several hours
45-54 Endurance threshold: 30-60 min
110-125 Life threatening and potentially lethal after 30-60 min of exposure
135 Lethal in 30 min
181 Lethal in 10 min
270 Acutely lethal

Where is hydrogen cyanide measurement mainly conducted?


Primarily at chemical plants where hydrogen cyanide is in use or ironworks, metal-plating plants, etc. where hydrogen cyanide is generated.



What kind of substance is arsenic?


Arsenic is a fairly common fragile crystalline metalloid ranging in colour from silver-white to black. It can be produced industrially through a chemical reaction using carbon to reduce arsenious acid in to its elements.
All compounds containing arsenic are toxic and when they comes in contact with acid or acid vapour, a highly toxic gas (arsine) occurs.
It is mainly used in insecticides, herbicides, desiccants, and in semiconductor fabrication.


How does it affect the human body?


It frequently affects the function of the digestive organs, causing loss of appetite, convulsions, nausea, constipation or diarrhea, hepatic disorders, and in severe cases, blood may be vomited up or found in feces, leading to a state of collapse or shock, and in extreme cases may be fatal. Moreover, it is considered to have carcinogenic effects on skin, lungs, and liver, too.


Where is arsenic measurement mainly conducted?


For prevention/detection of arsenic leaks at semiconductor fabrication facilities, especially measurement using detector tube systems is common.
Although, the monitoring of arsenic concentrations contaminating the natural environment (soil and water) is generally conducted using analytical instruments and devices, the Aichi Environmental Research Center, (Aichi, Japan) conducted extensive research using gas detector tube systems, and the results have been publicised in Japan (1993).

Hydrogen peroxide


What kind of substance is a hydrogen peroxide?


Hydrogen peroxide is a clear, unscented and oily liquid that is water insoluble. It can be extracted with mercury oxide after dissolving α-ethyl anthraquinone in an industrial solvent and oxidising in a (redox reaction). In general, hydrogen peroxide is commercially available as a 30% solution.
It also interacts as a reducing agent and a powerful oxidiser. When metal catalysts in fine particle form (e.g. copper, silver or platinum) trigger decomposition, high concentrations of oxygen/steam are produced that can combust explosively.
Hence, hydrogen peroxide is used in 3% solutions not only as a disinfectant, or a bleaching agent for paper, pulp, and natural fibers, but, also as an oxidiser, sterilizer, reducing agent, and even as liquid rocket fuel.


How does it affect the human body?


It is highly caustic to skin and mucous membranes, while a 30% solution can cause severe inflammation of eyes and skin upon contact. It is commonly known, that in work environments where hydrogen peroxide is in use, exposure to the vapour can have a bleaching effect on hair. If larger quantities are ingested, gastritis and acute toxic effects such as esophagitis, and chronic toxicity symptoms are likely.


Where is hydrogen peroxide measurement mainly conducted?


The maximum permitted concentration of hydrogen peroxides in work environments is 1ppm in TLV-TWA of ACGIH (2006).

Hydrogen chloride


What kind of substance is hydrogen chloride?


HCl is a strongly pungent, colourless to slightly yellowish gas. In nature it occurs in volcanic gas and in the human body's gastric juices as hydrochloric acid (HCl dissolved in water).
It can be produced by the direct reaction of hydrogen and chlorine, or in a laboratory by dripping concentrated hydrochloric acid into a strong sulphuric acid solution.
Generally it is marketed as hydrochloric acid in 35-37% concentrations. Its main uses are in the production of: medical supplies, pigment dye intermediates, inorganic chlorides, chloroethylene (i.e. vinyl chloride), methyl chloride as well as etchants (i.e. etching solutions).


How does it affect the human body?


Contact with eyes or skin causes inflammation.
When inhaled, it irritates mucous membranes in throat or nose, and causes coughing.
When substantial amounts are inhaled it can cause pulmonary oedema and even death.

Hydrogen chloride
0.5-1 Light irritation
5 Irritating to the nose and accompanied with a light sense of nausea
10 Cause strong nasal irritation, and exposure for 30 minutes becomes unbearable
35 Cause throat irritation after brief exposure
50 Limit that can be endured for a short time
1000 Potentially fatal

Where is hydrogen chloride measurement mainly conducted?


In all chemical plants, semiconductor fabrication facilities, oil refineries, where HCl is generated or discharged in the context of chemical reactions or combustion.

Sulphuric acid


What kind of substance is sulphuric acid?


One common production method involves burning sulphur or pyrites (usually iron sulphide), to obtain sulphur dioxide which is then oxidised, and dissolved in water.
Sulphuric acid is one of the most common basic materials, and it is used in fertiliser, pigment dye, petroleum refining, organic compound production, as well as myriad other uses in the chemical industry.


How does it affect the human body?


Contact with the skin can cause dermal dehydration or corrosion and severe acid burns. If its vapour is inhaled for longer periods, tooth erosion, damage to respiratory organs, and even pneumonia or pulmonary oedema can ensue. Extended contact with the eyes can cause blindness.

Sulphuric acid
0.1-0.5 Causes slight irritation
1.5-2.5 Causes irritation and discomfort
5 Endurance threshold (without lasting detrimental effects): 5 minutes
10-20 Strongly irritating until it is no longer bearable

Where is sulphuric acid (mist) measurement mainly conducted?


In such processes as the electrolysis of solutions containing sulphuric acid, or the fusion of metals with diluted sulphuric acid, the liquid foams and gives off sulphuric acid mist. Therefore, environmental measurement of sulphuric acid (mist) is conducted at workplaces where these processes are common in order to ensure safe working conditions for the operatives involved.
Although, titrimetry and absorptiometry are common analytical methods used to measure sulphuric acid (mist), simple analysis with gas-detector tubes is expected to increasingly be used in occupational safety management.

Ethylene oxide


What kind of substance is ethylene oxide?


It is a colourless highly water-soluble substance that is in its gaseous state at normal (room) temperature and has an ether-like odour. It is frequently used in organic compound formation, as a colourant, surface-active agent (surfactant), as well as for sterilizing medical instruments.
Its explosive range is very wide with an LEL (lower explosive limit) of 3.0% and a UEL (upper explosive limit) of 100%. With a very low ignition point of -17.8ºC (0ºF), its vapour is volatile enough to explode even in the absence of air / oxygen.
Moreover, as there are indications that it may be a carcinogen, the Japan Society for Occupational Health and the ACGIH stipulate a TLV (Threshold Limit Value) and administrative concentration threshold of 1ppm.
In addition, in Japan Air Pollution Control Law it is included among the "Substances Requiring Priority Action" as it is thought to pose a significant health risk among the hazardous air contaminants.


How is ethylene oxide measured?


As part of th leak check protocol for comparatively high concentrations, it is measured with (flammable) gas detector alarms, gas detector tubes, etc.
To measure ethylene oxide in ambient air, various contaminant measurement manuals recommend solid-phase sampling involving solvent-extraction gas chromatographic mass spectrometry.
In general, working environment standards prescribe gas chromatography of substances in solid state.



What kinds of substances are dioxins which have recently become an issue?


Dioxins are normally colourless solids which are generated naturally as byproducts during a process in which carbon, oxygen, hydrogen and chlorine are heated (as a result of combustion during incineration of garbage, for example).
According to the Law Concerning Special Measures Against Dioxins, polychlorinated dibenzofurans (PCDF), polychlorinated dibenzo-para-dioxins (PCDD) and coplanar polychlorinated biphenyls (coplanar PCB) are defined as dioxins.
Regarding the toxicity of dioxins, of PCDD, dioxins in which chlorine is located at positions 2, 3, 7 and 8 (2, 3, 7, 8-TCDD) are the most toxic. The toxicity of 2, 3, 7, 8-TCDD is defined as 1, and the toxicity of other dioxins is expressed using coefficients obtained by conversion from the toxicity of 2, 3, 7, 8-TCDD.

Data concerning the quantities and concentrations of many dioxins is expressed using a unit called the toxic equivalent (TEQ) of the value resulting from the summing up of the toxicity of each type of dioxin. The environmental standard related to atmospheric pollution is no more than 0.6 pgTEQ/m3 as an average value for one year, and the tolerable daily intake for the time being is no more than 4 pgTEQ/1 kg of body weight/day (4 picograms per 1 kg of body weight for 1 day).

Note: pg (picogram) = 10 – 12 g (one trillionth of one gram)


Is it possible to measure the quantity of dioxins in the air using a simple method such as a detecting tube?


Measurement of concentration is performed on extremely small quantities, so it is quite impossible to measure concentration using a simple method such as a detecting tube. A large quantity of sample air is filtered and collected using a sampler, pre-processing such as cleaning up is carried out, and then an analysis is performed using a high resolution gas chromatograph mass analyser (HRGC/HRMS). It may seem easy to describe this procedure in words, but the actual analysis involves the use of complicated processes.

Chlorine dioxide


What kind of gas is chlorine dioxide?


It has a pungent odor, is heavier than air, and is red to yellow in colour. It readily dissolves in water (Solubility: 0.8 g/100 ml at 20ºC), and is often used even as a solution in water. Chlorine dioxide itself is incombustible, but has extremely high oxidizability, and poses a danger of fire or explosion due to contact with combustible matter or reductive matter, or as a result of exposure to heat, sunlight, impact, or sparks. Representative industrial applications include disinfectant, which utilizes this powerful oxidation reaction, and also bleaching agent for fibers, pulp and foodstuffs. When using chlorine-base bleaching agent or detergent, for example, it is necessary to take care because chlorine dioxide may be inadvertently generated.


How does it affect the human body?


Chlorine dioxide has even greater irritability and toxicity than chlorine, and seriously irritates the eyes, skin and windpipe. It has been reported that at a concentration of 5 ppm, chlorine dioxide exhibits definite irritability, while at 20 ppm, it can result in death in a short time, and even at 0.1 ppm, chronic exposure to chlorine dioxide may result in various symptoms such as inflammation of the windpipe. Acute symptoms such as pulmonary edema may occur after several hours of exposure, so when there is acute exposure it is essential to obtain a diagnosis of a physician and also subsequent follow-up.



What kind of substance is mercury?


Mercury is a liquid that shines silver-white. It is the only metal that is a liquid at normal temperature.
The specific gravity of mercury is an extremely high value of 13.6, making it very heavy. On the other hand, it readily evaporates, and easily forms amalgams with a variety of metals.
Mercury is a highly toxic substance as is also evidenced by reports concerning poisoning due to methyl mercury. However, it is widely used not only as an industrial reagent, but also in measuring instruments such as thermometres, and also in agriculture, batteries (at present, it is used only in button batteries), and in drugs and medicines.
In days gone by, if you cut or grazed yourself, the first thing that you did was apply mercurochrome to the wound. Previously, mercurochrome was kept in all homes as a household antiseptic, but nowadays it is virtually no longer used because it uses mercury (its use is not prohibited, and if you go to a chemist’s shop you can still purchase it).


How does it affect the human body?


If mercury vapour is inhaled, various psychological symptoms such as loss of appetite, a headache, heaviness of the head, general malaise, minor trembling, and insomnia are likely to occur. Mercury is also absorbed through the skin.
The allowable concentration of mercury stipulated by the Japan Association of Industrial Health is 0.025 mg/m3 for mercury vapour. The value stipulated by TLV (TWA) of ACGIH, for both a single element and an inorganic compound, is 0.025 mg/m3, and the value at the control temperature stipulated by the Ministry of Health, Labour and Welfare is 0.05 mg/m3.


What are the main kinds of places where mercury is measured?


It is measured mainly at chemical plants and measuring instrument manufacturing facilities where gases are generated (discharged) along with metal refining and processing of waste matter.
JIS (K0222) stipulates the method of atomic absorption analysis (measurement). Simplified measurement employing a detecting tube for mercury vapour (No. 40, Measurement range: 0.05 – 13.2 mg/m3) is also used in various places for various purposes.



What kind of substance is tetrachloroethylene?


This substance is also called perchloroethylene. It is a volatile substance which is colourless and emits a characteristic odor.
Tetrachloroethylene is noncombustible and easily dissolves oil, so it is used as a solvent for dry cleaning and also for degreasing and washing metal parts.
Previously, tetrachloroethylene was covered by the Ordinance On Prevention of Organic Solvent Poisoning. In 2014, however, this ordinance was revised to become the Ordinance on Prevention of Hazards due to Specified Chemical Substances. As a result, tetrachloroethylene came to be ranked as a “special organic solvent, etc.” among type 2 substances of specific chemical substances. It also became a special controlled substance, and it became mandatory to devise measures based on its carcinogenicity.
In addition, according to the partial revision of the Work Environment Evaluation Criteria, the control concentration will be reduced from 50 ppm to 25 ppm commencing October 1, 2016.


What is the effect of tetrachloroethylene on the human body?


Inhaling or orally ingesting tetrachloroethylene can cause dizziness, a headache, a stomachache, nausea, a feeling of weariness, or loss of consciousness, and can also irritate the eyes and skin. It is also considered that this may cause cancer.

The allowable concentration is currently being examined. TLV-TWA* stipulates a value of 25 ppm.

*TLV-TWA: This is the time-weighted average allowable concentration stipulated by the American Conference of Governmental Industrial Hygienists. It is the time-weighted average that does not exert any harmful effect on a worker who works repeatedly for 40 hours a week at the rate of 8 hours per day.


At what kinds of places is tetrachloroethylene measured?


The places where measurement performed mainly using a detecting tube as follows:
- Measurement of the work environment for the purpose of controlling occupational health
- Measurement of discharged water or underground water for the purpose of preventing water pollution
- Investigation of the situation regarding pollution at a site where there is soil pollution
- Measurement of the concentration of exhaust gas for the purpose of preventing air pollution