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In 1930, Thomas Midgley, an American chemist, inhaled a breath of a new gas he had developed and then used it to blow out a candle.
His invention, carbon tetrachloride, was a safe replacement for the toxic trio of ammonia, chloromethane and sulphur dioxide used as the coolant in refrigerators. These CFCs were so useful that, by the 1960s, they were used as a propellant dispensing everything from deodorant to fire extinguishers.
In 1974, Sherry Rowland and Mario Molina, two chemists at the University of California, proved that CFCs were causing the destruction of the ozone layer and a dramatic rise in skin cancer. It took till 1989 before the Montreal Protocol was signed, calling for an end to all CFC production.
