Invisible Killer

Among modern technology's more unwelcome gifts is a man-made surplus of carbon monoxide, a toxic gas that cannot be seen or smelled. One way CO is formed is by burning any substance that contains carbon--fuel oil, for example, or tobacco. As a byproduct of the incomplete combustion of gasoline, CO is a prime ingredient of auto exhaust, which is the main source of air pollution in big cities.

Scientists have known for a long time that in large amounts the gas severely impairs the ability of the blood's hemoglobin to carry oxygen from lungs to tissues. The result is a loss of energy and a crippling of both mental and physical reactions. Inhaling the gas from auto exhaust has become a popular method of suicide. Now, because the highly industrialized Northern Hemisphere contains more than 90% of the world's CO, U.S. scientists are voicing new concern about its effects.

Smaller Babies. According to a recent report by the National Academy of Sciences, the gas becomes dangerous when it reaches levels of ten parts per million parts of air--a level that is no rarity in today's congested cities. At that point it can harm pregnant women and victims of bronchitis, emphysema and chronic heart disease. A damaged heart, for example, may be unable to compensate for reduced oxygen supply, and death may result. In Chicago and Philadelphia, says John Middleton, a top federal air-control official, the CO danger point "is exceeded throughout one-third to one-half of the day, and in Los Angeles more than 40% of the time." Each day in Los Angeles, cars spew out 20 million pounds of CO--enough to decrease the blood's oxygen-carrying capacity in some people by 20%.

In Manhattan last week, a three-day conference sponsored by the New York Academy of Sciences revealed that surprisingly low doses of the gas can be dangerous. Some scientists are even concerned about CO in tobacco smoke as well as auto exhaust. As they see it, the gas may explain why women who smoke cigarettes during pregnancy tend to have smaller babies than nonsmoking mothers.

Dr. Thomas Rockwell, director of Ohio State University's driving-research laboratory, also had bad news for motorists in smoggy areas, whether or not they smoke. Under some conditions, says Rockwell, a driver's perception is dangerously impaired by CO in his blood. He may have trouble detecting when a car ahead is slowing down; he can even fail to notice when its brake lights flash on.

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