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Top Questions

What creates carbon monoxide in a home?

What is carbon monoxide and where is it found?

What does carbon monoxide smell like?

Which gas is known as the silent killer?

Carbon monoxide (CO), is a highly toxic, colorless, odorless, flammable gas produced industrially for use in the manufacture of numerous organic and inorganic chemical products. Carbon monoxide is also present in the exhaust gases of internal-combustion engines and furnaces as a result of incomplete conversion of carbon or carbon-containing fuels to carbon dioxide, and it is a major air pollutant. Additional sources of carbon monoxide in the home include emissions from fuel-burning equipment such as portable generators, gas or kerosene heaters, gas stoves, fireplaces, wood stoves, and water heaters, particularly if these devices are poorly vented, malfunctioning, or allowing exhaust gases to flow back into indoor spaces. Tobacco smoke is another source.

Criteria air pollutants

Six major air pollutants have been designated by the U.S. Environmental Protection Agency as “criteria” pollutants—meaning that the concentrations of these pollutants in the atmosphere are useful as indicators of overall air quality. They are:

Health effects and treatment

Carbon monoxide is toxic because red blood cells absorb it instead of oxygen, thus interfering with the transport of oxygen from the lungs to the tissues that require it. Symptoms of carbon monoxide poisoning include headache, weakness, dizziness, nausea, fainting, and, in severe cases, coma, weak pulse, and respiratory failure. Treatment must be prompt and includes respiratory assistance and the administration of oxygen, sometimes under high pressure. See also carbon monoxide poisoning.

Steps should be taken to prevent carbon monoxide poisoning, as recommended by environmental and public safety authorities. Fuel-burning appliances should be installed properly and maintained regularly. Furnaces, chimneys, and flues should be checked for leaks, blockages, and unsafe venting. Generators, grills, camp stoves, and similar fuel-burning equipment should be used only outdoors and away from doors, windows, and vents. Motor vehicles should not be operated in attached garages from which exhaust can enter indoor spaces.

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oxide: Oxides of carbon

Because carbon monoxide cannot be detected by sight or smell, it may accumulate unnoticed in enclosed or poorly ventilated spaces. As an additional safety measure, carbon monoxide alarms should be installed in homes. These alarms detect carbon monoxide in the air and sound an alarm when CO concentrations remain high enough over a prolonged period to pose a hazard. Carbon monoxide alarms are different from smoke detectors, but sometimes the two are combined in the same apparatus.

Production

In manufacturing processes carbon monoxide is made by passing air through a bed of incandescent coke or coal, or by the reaction of natural gas with oxygen at high temperatures in the presence of a catalyst. The resulting carbon monoxide generally is contaminated with other substances, such as nitrogen or carbon dioxide, which may be removed if they are undesirable in the intended application.

Properties and uses

Carbon monoxide condenses to a liquid at −192 °C (−314 °F), and it freezes at −205 °C (−337 °F). It is only slightly soluble in water, and its physical properties closely resemble those of nitrogen.

Carbon monoxide reacts with water vapor at high temperatures, forming carbon dioxide and hydrogen; this process has been used as a source of hydrogen for combination with nitrogen in the synthesis of ammonia. With caustic alkalies carbon monoxide forms alkali formates, which can be converted into formic acid or alkali oxalates for the production of oxalic acid. With certain metals carbon monoxide forms compounds called carbonyls, many of which are volatile; this reaction has been used in the purification of nickel. Carbon monoxide and hydrogen are the starting materials in the manufacture of methanol and are also used in the preparation of aldehydes and alcohols from olefins and in making mixtures of liquid hydrocarbons suitable for use as fuels. Gas mixtures containing varying ratios of carbon monoxide and molecular hydrogen are called synthesis gas or syngas.

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