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Enter the CFCs |
CFCs were invented about 65 years ago during a search for a new, nontoxic substance that could serve as a safe refrigerant. One of these new substances, often known by the DuPont trademark Freon , soon replaced ammonia as the standard cooling fluid in home refrigerators. It later became the main coolant in automobile air conditioners.
The 1950s and 1960s saw CFCs used in a variety of other applications: as a propellant in aerosol sprays, in manufacturing plastics, and as a cleanser for electronic components. All this activity doubled the worldwide use of CFCs every six to seven years. By the early 1970s, industry used about a million tons every year.
Yet as recently as the late 1960s, scientists remained unaware that CFCs could affect the atmosphere. Their ignorance was not from lack of interest, but from lack of tools. Detecting the minuscule concentrations of these compounds in the atmosphere would require a new generation of sensitive detectors.
After developing such a detector, the British scientist James Lovelock, in 1970, became the first to detect CFCs in the air. He reported that one of these compounds, CFC-11, had an atmospheric concentration of about 60 parts per trillion. To put that measurement in perspective, the concentration of methane (natural gas) is 25,000 times greater. Twenty years earlier, merely detecting methane had been considered a major feat.
Lovelock found CFC-11 in every air sample that passed over Ireland from the direction of London. That was not surprising, because most major cities, including London, widely used CFCs. However, Lovelock also detected CFC-11 from air samples directly off the North Atlantic, uncontaminated by recent urban pollution.
This unexpected discovery prompted Lovelock to do further studies. Accordingly, he asked the British government for a modest sum of money to place his apparatus on board a ship traveling from England to Antarctica. His request was rejected; one reviewer commented that even if such a measurement succeeded, he could not imagine a more useless bit of knowledge than finding the atmospheric concentration of CFC-11.
But Lovelock persisted. Using his own money, he put his experiment aboard the research vessel Shackleton in 1971. Two years later the British researcher reported that his shipboard apparatus had detected CFC-11 in every one of the more than 50 air samples collected in the North and South Atlantic. Lovelock correctly concluded that the gas was carried by large-scale wind motions. He also stated that CFCs were not hazardous to the environment, a conclusion soon to be proven wrong. |
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