INTRODUCTION Damage to vegetation as a result of air contaminants has been recorded in the United States for decades. As industrialization has progressed@ air pollution has increased in terms of not only the amount of pollutants emitted but also the kind of pollutants. Before World War II@ the principal air pollutants causing the most plant damage were sulfur dioxide and illuminating gas. It was later found that the toxic compound in illuminating gas was ethylene. At the start of World War II@ aluminum and steel manufacturing and phosphate production increased tremendously@ adding fluorides to the list of plant-damaging air pollutants. In the 1950s@ extensive field and laboratory studies revealed the damaging effects of smog constituents on plants--constituents that apparently did not arise from specific industrial sources but developed over large urban or industrialized areas and were then dispersed@ injuring vegetation over hundreds of square miles. These effects were first noted in the western part of the United States@ specifically in the Los Angeles basin and the surrounding areas. Later@ they were noticed in other areas of the United States.@ especially near large population centers. Soon@ other so-called smog symptoms also began to be noticed. These new symptoms differed somewhat from the original smog effects but they too seemed to be associated with large population centers@ especially in the east.
API 4064 VOL 1-1970 history
1970API 4064 VOL 1-1970 Annual Report - ECONOMIC IMPACT OF AIR POLLUTANTS ON PLANTS (VOLUME I)