In 1990, Congress ordered gasoline makers to add compounds called oxygenates to their products in the belief they would cut down on pollutants that contribute to ozone -- a key component in smog. Motorists have been paying a couple of cents extra per gallon for the additives ever since the mid-1990s.

Now the National Research Council reports that they don't work. In the words of the report they are "likely to have little air- quality impact in terms of ozone reduction."

• The most common oxygenates are ethanol -- made from corn, wheat and other crops -- and an artificial chemical called MTBE.

• The law now requires oxygenates in nine cities with serious air pollution problems.

• In all, 17 states have added oxygenates to fuels.

• The new study says that ethanol -- which enjoys wide support from farm-state politicians and large agribusinesses -- might actually contribute to smog rather than decrease it.

Ethanol evaporates readily, increasing the release into the air of pollutants.

The Environmental Protection Agency says it will reserve judgment about oxygenates until at least July. That's when an EPA- appointed panel will present its findings on the health effects of MTBE.

The EPA and some environmental activists have contended that ethanol is a cheap, effective way of cutting down on air pollution. The oil industry, however, says it doesn't want to be forced to add oxygenates.

Source: Traci Watson, "Anti-Smog Fuel Additives Aren't Working, Report Says," USA Today, May 12, 1999.