Greta Jimenez
Chlorofluorocarbons (CFCs) are nontoxic, nonflammable chemicals that contain atoms of carbon, chlorine, and fluorine. They are used in aerosol sprays, blowing agents, and refrigerants. CFCs are largely inert in the lower atmosphere, but they undergo significant reactions in the upper atmosphere or stratosphere. CFCs are known to cause stratospheric ozone depletion, which has harmful effects on human health and the environment. This has led to global efforts to phase out their use and reduce their impact on the atmosphere. With their discovery in the 1920s and wide range of applications, the question arises as to whether chlorofluorocarbons are a primary or secondary pollutant.
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What You'll Learn
Chlorofluorocarbons (CFCs) are nontoxic, nonflammable chemicals
CFCs are used in the manufacture of aerosol sprays, blowing agents for foams and packing materials, as solvents, and as refrigerants. Their nontoxic and nonflammable nature made them well-suited for these applications. CFCs are also far less flammable than methane, due to the presence of fewer C-H bonds and the quenching of free radicals by halides.
However, while CFCs are safe and inert in the lower atmosphere, they undergo significant reactions in the upper atmosphere or stratosphere. In 1974, University of California chemists F. Sherwood Rowland and Mario Molina discovered that CFCs could be a major source of inorganic chlorine in the stratosphere, following their photolytic decomposition by UV radiation. This released chlorine contributes to the destruction of the ozone layer, which is essential for absorbing harmful UV-B radiation that can cause biological damage to plants and animals.
The groundbreaking research by Rowland and Molina brought worldwide attention to the impact of human-contributed pollution and led to the Montreal Protocol in 1987, which phased out the use of CFCs globally. This international agreement included restrictions on the production of specific CFCs and halons, recognising the urgent need to control these compounds to protect the ozone layer.
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CFCs are classified as halocarbons
Chlorofluorocarbons (CFCs) are nontoxic, nonflammable chemicals containing atoms of carbon, chlorine, and fluorine. They are used in the manufacture of aerosol sprays, blowing agents for foams and packing materials, as solvents, and as refrigerants. CFCs are classified as halocarbons, a class of compounds that contain atoms of carbon and halogen atoms. Halocarbons are compounds that contain halogens (such as fluorine, chlorine, bromine, and iodine) bonded to other elements with more electro negativity, such as carbon.
CFCs were first synthesized in 1928 by Thomas Midgley, Jr. of General Motors, as safer chemicals for refrigerators used in large commercial applications. They were also used in air conditioning and aerosol spray cans. The compounds are inert and essentially nontoxic, which made them well-suited for these applications. However, these same characteristics also made them a danger to life on Earth.
In 1974, two University of California chemists, Professor F. Sherwood Rowland and Dr. Mario Molina, discovered that CFCs could be a major source of inorganic chlorine in the stratosphere following their photolytic decomposition by UV radiation. This chlorine was then released and became active in destroying ozone in the stratosphere. Ozone is a trace gas located primarily in the stratosphere that absorbs harmful ultraviolet radiation in the wavelengths between 280 and 320 nm of the UV-B band, which can cause biological damage to plants and animals. Therefore, a loss of stratospheric ozone results in more harmful UV-B radiation reaching the Earth's surface.
Due to the harmful effects of CFCs on the ozone layer, their manufacture has been phased out under the Montreal Protocol, and they are being replaced with other products such as hydrofluorocarbons (HFCs) and hydrofluoroolefins (HFOs). Industry has also developed two classes of halocarbon substitutes for other uses: hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs).
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CFCs are used in aerosol sprays, blowing agents, and refrigerants
Chlorofluorocarbons (CFCs) are nontoxic, nonflammable chemicals that contain atoms of carbon, chlorine, and fluorine. They are used in aerosol sprays, blowing agents, and refrigerants.
CFCs are used in aerosol sprays as propellants. They have been used in products such as bug sprays, paints, hair conditioners, and other healthcare products. In 1930, General Motors and Du Pont formed the Kinetic Chemical Company to produce Freon (a Du Pont trade name for CFCs) in large quantities. By 1935, Frigidaire and its competitors had sold 8 million new refrigerators using Freon-12 (CFC-12).
CFCs are also used as blowing agents for foams and packing materials. They are useful in these applications because of their low toxicity, reactivity, and flammability.
CFCs are used as refrigerants due to their nontoxicity and high boiling points. After a series of fatal accidents involving the leaking of chloromethane from refrigerators in the 1920s, CFCs were developed as a safer alternative. CFCs, such as Freon, became the preferred coolant in large air-conditioning systems and refrigerators.
Despite their useful applications, CFCs have been found to contribute to ozone depletion in the upper atmosphere. In 1974, University of California chemists Professor F. Sherwood Rowland and Dr. Mario Molina showed that CFCs could be a major source of inorganic chlorine in the stratosphere, which destroys ozone molecules. This leads to an increase in harmful UV-B radiation reaching the Earth's surface. As a result, the manufacture of CFCs has been phased out under the Montreal Protocol, and they are being replaced with other products such as hydrofluorocarbons (HFCs) and hydrofluoroolefins (HFOs).
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CFCs deplete the Earth's atmospheric ozone layer
Chlorofluorocarbons (CFCs) are nontoxic, nonflammable chemicals that contain atoms of carbon, chlorine, and fluorine. They are used in the manufacture of aerosol sprays, blowing agents for foams and packing materials, as solvents, and as refrigerants. CFCs are classified as halocarbons, a class of compounds that contain atoms of carbon and halogen atoms.
In 1974, Professor F. Sherwood Rowland and Dr. Mario Molina of the University of California, Irvine, discovered that CFCs could deplete the Earth's atmospheric ozone layer. This discovery was among the first instances of human-contributed pollution on a planetary scale. They found that CFCs could be a major source of inorganic chlorine in the stratosphere following their photolytic decomposition by UV radiation. This released chlorine would then become active in destroying ozone in the stratosphere.
Ozone is a molecule made up of three oxygen atoms, O3, in the Earth's stratosphere. The ozone layer absorbs and prevents harmful ultraviolet (UV-B) radiation from reaching the Earth's surface. This radiation can cause biological damage to plants and animals and has been linked to an increased risk of skin cancer, sunburn, permanent blindness, and cataracts. Therefore, a depletion of the ozone layer would have detrimental effects on life on Earth.
Molina's research indicated that CFCs would remain in the atmosphere for a long time, between 40 and 150 years, before drifting high enough for solar radiation to split off a highly reactive chlorine atom from the CFC molecule. This chlorine atom could then react with ozone molecules, destroying them and depleting the ozone layer. This hypothesis was supported by laboratory studies, which showed that chlorine atoms could indeed destroy ozone.
The discovery by Rowland and Molina, along with evidence of a thinning ozone layer over the Antarctic, led to worldwide concern and action. In 1987, 56 countries agreed under the Montreal Protocol to cut CFC production and use. This agreement was strengthened over time, eventually leading to a worldwide phase-out of CFCs and the development of safer alternatives.
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CFCs are skin and eye irritants
Chlorofluorocarbons (CFCs) are nontoxic, nonflammable chemicals containing atoms of carbon, chlorine, and fluorine. They are used in the manufacture of aerosol sprays, blowing agents for foams and packing materials, as solvents, and as refrigerants. CFCs are classified as halocarbons, a class of compounds that contain atoms of carbon and halogen atoms.
CFCs are known irritants to the upper airway with ambient exposure. They may also cause cryogenic effects on tissue. Liquid CFCs with low boiling points or under pressure can cause freezing of the skin if they come into contact with the body for more than 3 to 5 seconds. Frostbite of the eyelids can occur and may be severe. Dermal contact with CFCs in liquid form is likely to cause a sensation of coldness and possibly frostbite caused by rapid evaporation.
In addition to the above, CFCs are skin and eye irritants. Irritation of the skin, eye, and respiratory tract has been observed following exposure to CFCs. CFCs are more acutely toxic to rabbits than to mice via the oral route of exposure. Dogs have demonstrated vomiting, lethargy, nervousness, and tremors following inhalation exposure to CFCs. High-concentration exposures to dogs, monkeys, and rats have resulted in cardiac arrhythmias.
Transient low-concentration CFC exposures result in eye, nose, and throat irritation. Pulmonary irritation, bronchial constriction, cough, dyspnea, and chest tightness may develop after inhalation. Central nervous system depression, bronchial constriction, chest tightness, cough, difficulty breathing, pulmonary edema, dizziness, headache, confusion, and incoordination are also associated with exposure to high concentrations of CFCs.
CFCs are classified as primary pollutants, which are pollutants that are formed and emitted directly from particular sources.
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Frequently asked questions
Chlorofluorocarbons (CFCs) are nontoxic, nonflammable chemicals containing atoms of carbon, chlorine, and fluorine.
Chlorofluorocarbons are primary pollutants as they are emitted directly from particular sources.
CFCs are emitted from refrigeration, air conditioning, and aerosol spray cans.
CFCs are one of the primary causes of stratospheric ozone depletion, which can lead to an increase in harmful UV-B radiation reaching the Earth's surface.
The manufacture of CFCs has been phased out under the Montreal Protocol, and they are being replaced with other products such as hydrofluorocarbons (HFCs) and hydrofluoroolefins (HFOs).
