Pioneering research into the structure of matter and the vulnerability of the Earth's protective ozone layer have won this year's Nobel prizes for physics and chemistry.
Martin Perl, of Stanford University, and Frederick Reines, of the University of California, share the physics prize for their separate discoveries of two sub-atomic particles that help to explain the birth of the universe.
The Nobel prize for chemistry is shared by three scientists for their work on the ozone layer: Paul Crutzen, a Dutchman working at the Max Planck- Institute in Mainz, Germany, Mario Molina, of the Massachusetts Institute of Technology, and Sherwood Rowland, of the University of California.
The three chemists helped to show that the ozone layer is the Achilles' heel of the Earth's biosphere, the Swedish Academy of Sciences said. ''By explaining the chemical mechanisms that affect the thickness of the ozone layer, the three researchers have contributed to our salvation from a global environmental problem that could have catastrophic consequences.''
Paul Crutzen demonstrated in 1970 that atmospheric ozone could be destroyed by nitrogen oxides - environmental pollutants - in the presence of sunlight. Four years later, Molina and Rowland alerted the world to the threat to the ozone layer posed by the release of chlorofluorocarbons (CFCs), used in aerosol sprays and refrigerators. Their work led to the first restrictions on the release of CFCs during the late 1970s and early 1980s.
The Nobel Prize for Physics recognised the discovery of two of the 12 smallest constituents of the Universe - the tau particle, which is like an electron but thousands of times heavier, and neutrinos, produced by nuclear reactions within the Sun. The research opened up a new branch of astronomy.