Arboreal Pollution

In New Brunswick, N.J., where Joyce Kilmer is said to have written his verses praising trees, a leading botanist last week blamed them for their role in one of civilization's greatest concerns: air pollution. At a biometeorological conference at Rutgers, University of Nevada Professor Frits Went stated flatly that trees foul the air with ten times more pollutants than all of man's fires, factories and vehicles.

Such trees as fragrant pine and plants such as pungent sage produce the "blue haze" that occurs during summer, even over relatively uninhabited areas of land. They emit molecular substances known as terpenes and esters, which react with sunlight to form a smog similar to the one produced by man-made pollutants. Terpenes, says Went, like some industrial and automobile pollutants, are "incredibly toxic." In some parts of the West, where they are generated by sage, they actually inhibit the growth of other vegetation.

Fortunately for mankind, blue haze is usually purged from the atmosphere by rain and snow before it reaches dangerous concentrations. In samples of snow collected in a remote section of Yellowstone National Park--where man-made pollutants are not likely to be at fault--Went has found "little globs of asphaltic tar matter."

Despite his general indictment of tree-caused air pollution, Went also had a kind word for the tree's byproduct. Some of the important organic deposits in the earth's crust, such as petroleum and bituminous coal, he says, may well have come from arboreal air pollutants gradually deposited on earth by falling rain and snow.

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