WE ARE BEGINNING to wonder how dangerously befouled the area's air will have to get to accelerate congressional action on the Clean Air Act. Perhaps it's the quality of the air-conditioning in the Capitol. Or could it be that the denseness of the air has simply befuddled some of hte Senate-House conferees? Whatever the case, they are still having trouble arranging meetings, much less getting together on effective ways to curb pollution from motor vehicles.

To get a greater sense of urgency, the conferees might consider moving their sessions outdoors. They could start on the Capitol's west terrace, from which - especially in late afternoon - they could get a good eyeful of the city's auto exhausts fermenting in the heat. That should persuade at least some of the House conferees to vote for the stricter emissions standards in the Senate bill, plus mandatory maintenance and inspection programs to make sure that vehicles' polution-control systems keep working as they should.

It's true that even the Senate standards would not clear the air in Washington and nearly 30 other regions where the traffic is too heavy. These areas will also have to expand mass transit and discourage auto travel by adopting stiff parking taxes and the like. But that's no reason to ask less of auto manufacturers. Indeed, firm tailpipe controls are doubly necessary because restrictions on auto use are so hard to obtain. To see this, the lawmakers need only go to New York City and watch Mayor Abe Beame fighting against a mid-Manhattan parking ban.

Next, the conferees would well advised to head back to Washington via the Jersey Turnpike; they should need no further examples of the connection between the law they write and the air they breathe. There's another factor to be considered, though, and it can be dramatized by a stop in Baltimore. The ozone clouds there have been even more noxious than the smog in Washington. Instead of curbing cars, Maryland authorities have ordered about 20 industries to curtail their operations and reduce hydro-carbon emissions by 25 per cent. That's an extreme example of the choice that many cities are going to face. As Environmental Protection Agency Administrator Douglas M. Costle warned recently, if autos are allowed to "pre-empt" the air, urban industrial growth will have to be sharply limited. It's one more point for the conferees to ponder as they return to the air-conditioned Capitol to decide the future condition of the nation's air.*