AIR POLLUTION - HISTORICAL TRENDS.

The composition of the atmosphere has changed remarkably over the last few millennia. These changes, especially in urban areas, have usually been the result of human activity. The changes have accelerated in recent centuries to such a degree that we are now able to detect shifts in the global concentrations of carbon dioxide, methane, nitrous oxide and a range of halogenated compounds. This paper will look at the social and economic pressures that force societies to adopt new fuels. It will then trace the history of the effects and of public reaction to the new and more polluting fuels. It is informative to examine how the public perceive the changes taking place and the response on the part of the legislators. Modern chemistry and meteorology allow us to take these descriptive materials and the statistical data gathered by early administrators to make a more objective assessment of the levels of pollution in early cities.