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The sheer bulk of big cities slows the cleansing winds; at the same time, rising city heat helps to create thermal inversions (warm air above cold) that can trap smog for days—a crisis that in 1963 killed 400 New Yorkers. Cars complete the deadly picture. While U.S. chimneys belch 100,000 tons of sulfur dioxide every day, 90 million motor vehicles add 230,000 tons of carbon monoxide (52% of smog) and other lethal gases, which then form ozone and peroxyacetyl nitrate that kill or stunt many plants, ranging from orchids to oranges. Tetraethyl lead in auto exhausts affects human nerves, increasing irritability and decreasing normal brain function. Like any metal poison, lead is fatal if enough is ingested. In the auto's 70-year history, the average American's lead content has risen an estimated 125-fold, to near maximum tolerance levels. Arctic glaciers now contain wind-wafted lead.
Air, Water & the Sewer
By the year 2000, an estimated 90% of Americans will live in urban areas and drive perhaps twice as many cars as they do now. The hope is that Detroit will have long since designed exhaust-free electric or steam motors. Another hope is nuclear power to generate electricity in place of smoggy "fossil fuels" (oil, coal), but even with 50% nuclear power, U.S. energy needs will so increase by 2000 that fossil-fuel use may quadruple. Moreover, nuclear plants emit pollution: not only radioactive wastes, which must be buried, but also extremely hot water that has to go somewhere and can become a serious threat to marine life.
Industry already devours water on a vast scale—600,000 gal. to make one ton of synthetic rubber, for example—and the resultant hot water releases the dissolved oxygen in rivers and lakes. This kills the oxygen-dependent bacteria that degrade sewage. Meanwhile, the country's ever-mounting sewage is causing other oxygen-robbing processes. By 1980, these burdens may well dangerously deplete the oxygen in all 22 U.S. river basins. The first massive warning is what happened to Lake Erie, where overwhelming sewage from Detroit and other cities cut the oxygen content of most of the lake's center to zero, turning a once magnificently productive inland sea into a sink where life is catastrophically diminished. With state and federal aid, the cities that turned Erie's tributaries into open sewers are now taking steps to police the pollution, and if all goes well, Erie may be restored to reasonable life in five or ten years.
But the problem goes on. Though one-third of U.S. sewage systems are below health standards, improving them may also kill lakes. The problem is that treated sewage contains nitrate and phosphate, fertilizing substances widely used in agriculture that make things worse in overfertilized lakes. Though nitrate is normally harmless in the body, intestinal bacteria can turn it into nitrite, a compound that hinders hemoglobin from transporting oxygen to the tissues, causing labored breathing and even suffocation.
The Systems Approach