Only one snag slowed the negotiations over my first maternity leave: who would be responsible for following the Clean Air Act while I was gone. I was then on The Post's editorial staff, and President-elect Reagan had made clear that the air bill would be the first in line in what was to be a sweeping undoing of federal environmental regulation. As it turned out, the Great Communicator had drastically misread public opinion on the environment. That soon-to-be baby now does long division and is planning his 10th birthday. The clean air rewrite is still being worked on.

Twenty years after the federal air pollution law was first passed, the two new versions now mired in a House-Senate conference are revised, expanded and toughened, but still clearly its lineal descendants. They deal with issues not then recognized as such -- acid rain, getting rid of CFCs -- and use new incentives in place of pure command-and-control regulation. But they both still suffer from the same fatal flaw: in a country where the vast majority of air pollution comes from energy use, much of that from transportation, we are trying to achieve clean air through a law that has little say over how much energy we use or how we get around.

To the limited extent that the country has had an articulated energy and transportation strategy during these 20 years, it has been: Burn more fossil fuels, build more roads. The only path available for improving the air has been to ratchet down allowed emissions for each ton of fuel burned and each mile driven. Much has been achieved this way, but there is an inevitable collision with economic growth. Eventually, the cost of the next step downward becomes too high.

By now it has become difficult even to define progress. Without doubt the nation's air is vastly cleaner than it would have been without a federal air pollution law. Yet more than 130 million people -- about half the population -- live in areas that do not meet the basic health standards for ozone and carbon monoxide. Automobiles produce far less pollution, but motor vehicle use is growing so fast it soon overtakes the effect of cleaner cars. Congress has spent untold hours fighting over how many grams per mile of which pollutant may emerge from an automobile tailpipe by what year. The dirty little secret is that the number of vehicle miles traveled is expected to double in most cities in 20 years. At that rate, these bitterly fought new standards will merely offset the added emissions.

The political process reflects the strains of this debate as well as the general political breakdown in Washington. Through 14 weeks of this House-Senate conference, the legislators themselves have met only four times. Rather than make publicly understandable big-picture choices, they are writing a bill that is technical detail piled on detail, special provision on top of special provision, most of it hammered out in staff negotiations behind closed doors. The process is tailor-made to accommodate the interests that provide the PAC money our appalling campaign finance arrangements require. The deals and tradeoffs are so numerous and so painful that the principal reason to hope a final agreement can be still be reached in the remaining few days of the session is the level of sheer desperation members feel to get the process over with.

The administration has been no help. President Bush made an enormous contribution when he introduced his version of the bill a year ago, and broke the decade-long stalemate over whether and how to control acid rain. Having thereby met, at least to his own satisfaction, his campaign pledge to be the "environment president," Bush turned his back on the issue. (Leon Billings, staff director to the Clean Air Act's principal author, former senator Ed Muskie, calls this the "Read my clips" presidency.) Since then, the administration has ignored any number of opportunities to contribute constructively, relying instead on its all-purpose legislative strategy, the veto threat.

An added complication is the belief in many state capitals that the federal government won't move aggressively enough to ensure adequately clean air. After 10 years of federal backpedaling on the environment, several states -- notably California and New York -- intend to take matters into their own hands. Industry understandably shudders at the prospect of different state standards requiring, for example, different automobile fleets state by state. Like land mines in an old battlefield, bits of the Reagan legacy keep turning up to threaten the present.

The compromise whose outlines are slowly emerging is worth having, though perhaps unworthy of the 10-year wait. The bill sets the country on a long march in the right direction -- more slowly than environmentalists believe is needed, more aggressively than affected industries would like. Decisions yet to be made could make a substantial difference, especially provisions that would finally make local transportation planners responsible for the air quality consequences of their decisions, and allow governors to use federal highway money for programs that reduce, rather than increase, motor vehicle pollution.

The country badly needs to get this bill passed and signed. The real challenge, once Washington is up to it, will then be to craft a new approach, one that deals with energy, transportation, clean air -- and greenhouse warming -- in one coherent package.

The writer is vice president of the World Resources Institute.