WITH THE passage of the Clean Air Bill now emerging from conference, the air will in fact become cleaner. The volume of pollutants blown into it every day by 251 million Americans as they go about their lives will diminish, with benefits to public health and the environment. Congress is demonstrating that even in this most divisive of subjects, it is capable of legislating. There had been some doubt about that, but the 13-year deadlock is finally broken. This kind of bill inevitably sets regions of the country, industries and social interests at each others' throats, but, compromise by compromise, it has kept moving.

It's now time to start thinking seriously about the next bill. Valuable though this year's legislation will be, it is rather narrow in terms of the requirements that are now emerging. This bill will probably be seen as the final great effort to carry out the agenda that developed in the early 1970s. The main questions in this year's bill have involved things such as the volume of hydrocarbons to be emitted by a car's tailpipe, or the amount of sulfur to be emitted by a power plant's stack -- questions that were first posed in Congress nearly two decades ago. But in the 1990s the country and its Congress are going to have to deal with much broader changes.

The number of cars in the United States is now growing twice as fast as the population. The demand for electricity is growing three times as fast. The present kinds of controls can have only limited effectiveness amid that kind of growth. Over the next decade, if environmental progress is to continue, Americans are going to have to think about cars that employ radically different technologies and power stations that do not generate carbon dioxide.

Present evidence does not prove that the world has yet begun to get warmer, but there is no doubt whatever that it will get warmer -- with profound and unpredictable consequences -- if concentrations of carbon dioxide continue to rise at the present rate. As the years pass, it is possible that future clean air bills will have to deal not only with the noxious byproducts of combustion, like this year's bill, but with the process of combustion itself.

The United States alone can't protect global air quality, for the developing countries and their growing industries are becoming major polluters. But if advanced technology is to provide solutions, it's going to have to come from the countries that have the greatest technical resources -- above all, this one. That may have to be the point of the next clean air bill.