Among the most serious dangers to public health is air pollution. It is at least as important as cancer and vascular disease as a cause of death, illness, and lost human potential, it is a major source of environmental damage, and it seems to be an inescapable accompaniment of industrial progress. In the 19th century we measured a country's power by its production of sulphuric acid, perhaps we should now do so by the acid particles breathed by its citizens? After the very obvious air borne disasters of the 1950s due to fogs in Britain, Mexico, and the USA, there was a rapid legislative and technical response to reduce obvious sources of …