My constituents in Los Angeles would be more than a little upset with The Post's contention that Los Angeles and many of the most polluted cities of the nation will never be able to achieve healthful air. The Post's argument {editorial, Nov. 20} that we should set looser health protection standards for such cities as Los Angeles, New York and Houston, where air pollution problems are most severe, would condemn millions of Americans to unhealthful air.

The challenge before us should not result in our abandoning the health protection standards of the Clean Air Act in those areas that need them most. As chairman of the House subcommittee with jurisdiction over the Clean Air Act, I have held hearings this year in New York and Los Angeles, and I can say unequivocally that in those cities, as in other polluted cities across the nation, there is tremendous public concern over air pollution and support for continuing efforts to reduce it.

The public concern is understandable. The Environmental Protection Agency estimates that 75 million Americans in 60 areas of the country are breathing unhealthful air that fails to meet the standard for either ozone or carbon monoxide, or both. Roughly 30 million people live in especially polluted areas, such as Los Angeles, New York and Houston, where EPA data show pollution levels at double the standard.

A great deal more can be done to bring better air quality to America's cities without resorting to draconian restrictions on driving. State and local air pollution officials have recommended a long list of control measures that EPA has declined to implement, including guidelines to help states regulate air pollution from industrial sources, requirements for upgraded automobile inspection and maintenance, control of gasoline refueling vapors at the pump, and tighter tailpipe standards for cars, trucks and buses.

There are other innovative approaches not called for under current law. One prominent example is greater use of lower-polluting alternatives to gasoline, such as methanol, in our nation's most polluted cities. An aggressive program promoting the use of these fuels could go a long way toward bringing even Los Angeles into compliance with the standards. In fact, the California Energy Commission concluded in 1986 that the Los Angeles area could be within striking distance of the standard in a decade through use of such fuels.

So let's not give up on clean air. This is not to say that we don't need a new deadline to replace the Dec. 31, 1987, date in the current Clean Air Act. It is clear that most urban areas will not be in compliance with the standards by that date. Any new deadline must, of course, be realistic, but it must also call for us to do all that we can to bring more healthful air to America's cities.

EPA's new air pollution policies would put off achievement of clean air standards 25 years for the nation's most polluted cities. That kind of time frame would make it more difficult for state and local agencies to put tough pollution controls in place. Hence, EPA's defeatist attitude on air pollution control is likely to become a self-fulfilling prophecy.

My approach, based on the recommendations of the national associations of state and local air pollution control officials, would extend the deadlines for various areas of the country for three, five or 10 years, depending upon the severity of the problem, and impose new pollution control requirements to ensure that the new deadlines can be met.

Poor air quality is bad for our health, bad for our economy and bad for our environment. We cannot, and must not, stop now in the effort to bring clean air to America's cities.

Henry A. Waxman

The writer is a Democratic representative from California.