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Topic section: CFCs and the ozone layer
TOPIC SECTION:
CFCs and the ozone layer

Of all the mod-cons that were popular in the 1950s, the refrigerator would have been close to the top of most people’s list. No longer did you have to shop every day or use unhygienic and largely unsuccessful meat-safes.

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Frigidaire refrigerator from the mid-1950s. The refrigerator entered many homes for the first time in second half of the 1950s. The American Frigidaire company produced its 20,000,000th refrigerating unit in 1956. 
Credit: Science Museum/Science & Society Picture Library

At the heart of the 1950s refrigerator was an exotic gas that remained a mystery to most of its owners. This chlorofluorohydrocarbon (CFC) – developed by the American inventor Charles Midgley in 1928 – was much safer than the poisonous ammonia and sulphur dioxide gases originally used in refrigerators. Completely inert and harmless to humans, it was also the ideal propellant gas for aerosol sprays. (Aerosols were becoming increasingly popular in the 1960s, used for practically everything: hair spray, deodorant, shaving foam, room freshener and oven cleaner.)

CFCs got into the atmosphere, where they were certainly invisible, but did not give rise to any concern at the ti

Since the mid-1980s, the global warming issue (‘Greenhouse Effect’) has come to the forefront of public debate

me. The situation began to change when James Lovelock, the inventor of the electron capture detector (ECD), bought a holiday home on the west coast of Ireland. Using his ECD to determine the origin of summer smogs in Bantry Bay, he noticed that CFCs (easily detected with the ECD) were reaching Ireland from across the Atlantic. He wondered if air currents were carrying the very stable CFCs around the world and hired a ship to travel to the South Atlantic to find out. He was able to show that CFCs were present in the atmosphere (in very low concentrations) even in the most remote places, but considered this finding to be a mere curiosity as the CFCs were obviously harmless.
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Frigidaire refrigerator showing the interior, mid-1950s. In the 1950s, refrigerators became more stylish and better insulated. As the cheap and apparently safe refrigerating fluid, CFCs played an key rôle in changing life styles and eating habits.
Credit: Science Museum/Science & Society Picture Library

However, Lovelock’s research raised the question of what happened to the CFCs if they were building up in the lower atmosphere. In 1974, Sherry Rowland and Mario Molina suggested that CFCs would react with ozone in the upper atmosphere, thereby destroying the ozone layer, which protects us from harmful ultraviolet radiation. Some chemical manufacturers and the aerosol industry resisted attempts to limit the production of CFCs. The discovery of a periodic thinning of the ozone layer above Antarctica by the British Antarctic Survey in 1985 generated enormous anxiety about possible increases in skin cancer. This widely felt concern led to the establishment of the Montreal ‘Protocol on Substances that Deplete the Ozone Layer’ two years later. This set off a process which brought about the eventual banning of CFCs in the developed world in 1996.

Meanwhile, many people began to regard aerosols, environmentally speaking, as a bad thing. Most CFC-filled aerosols were banned in the United States as long ago as 1978, and phased out voluntarily in the UK in 1989. Nearly all modern aerosols are filled with volatile hydrocarbons, usually propane or butane.

As hydrocarbons, they are also highly flammable, unlike CFCs, but fortunately accidents seem to be rare. In the 1990s, the refrigerant manufacturers marketed two groups of CFC substitutes –hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). So all was now well. Or was it? Since the mid-1980s, the global warming issue (‘Greenh
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Dobson's original ozone spectrometer, 1926.
Credit: Science Museum/Science & Society Picture Library
ouse Effect’) has come to the forefront of public debate. All these CFC substitutes contribute to global warming. As a result, environmental groups, such as Greenpeace, and the chemical industry are still at loggerheads over the HFCs. The HCFCs are already being phased out because they erode the ozone layer, though much more slowly than the CFCs. The ‘ozone wars’ have been largely replaced by the still unresolved ‘greenhouse wars’.

The history of CFCs (and DDT) shows that apparently harmless things can actually have a massive effect on our environment. How we assess these risks, when we often don’t know in which direction the danger lies, is a central issue for the twenty-first century and is fundamental to debates about new technologies such as GM foods and cloning.

 
 
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Topic section: Radioactivity
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Even after Hiroshima, there was little public anxiety about radioactivity. Luminous watch faces and instrument dials did not cause any concern, and even scientists took few precautions. The situation changed after the first H-bomb tests in the mid-1950s, and nuclear fallout became a major political issue.  > more

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Topic section: Pesticides
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When DDT and other insecticides were first introduced in the mid-1940s, they were considered to be a boon to society, preventing disease and increasing the supply of food. As evidence of their impact on the environment mounted, powerful devices were developed to detect even tiny traces of DDT. But the public was not reassured.  > more
 
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