In about 1900, methyl bromide and carbon tetrachloride became the first two commercial ozone-depleting substances (ODSs) used in fire protection, metal and fabric cleaning and pest control. However, it was the invention and mass marketing of CFCs in the 1930s that increased global emissions to levels that posed a threat to the ozone layer that was unappreciated at the time. In 1974, Mario Molina and F Sherwood Roland published their discovery that emission of CFCs would deplete the stratospheric ozone layer. In the next 13 years, the theory was verified, the Antarctic ozone ‘hole’ was discovered, and the Vienna Convention for the Protection of the Ozone Layer (1985) and the Montreal Protocol on Substances that Deplete the Ozone Layer (1987) were agreed upon by the world community. The 1987 Montreal Protocol, which had only mild controls on some ODSs, was strengthened with periodic amendments and adjustments from 1990 onwards to phase out a long list of ozone-depleting substances in both developed and developing countries.