The House begins debate today on a 479-page clean air bill that has the AFL-CIO and the U.S. Chamber of Commerce on the same side, and the 289 House Democrats so divided the leadership will not even risk a head count.

The bill is a series of amendments, mainly somewhat weakening or delaying, to the Clean Air Act of 1970. In that 1970 legislation Congress for the first time began forcing U.S. industry and the public at large to pay clean air's high cost - and the legislation has had some effect.

In the 30 years from 1940 to 1970 U.S. air pollutant output rose significantly; the Council on Environmental Quality says total yearly tonnages of all major regulated pollutants - "controlable" particulates, sulfur dioxide, carbon monoxide, hydrocarbons and nitrogen oxides - "grew substantially".

But in the 1970s that growth slowed eppreciably, stopped or - in the case of one pollutant, carbon monoxide - was reversed.

Now the question is whether to tighten the 1970 act and press on or ease up a little. Millions of dollars ride on these decisions, and Rep. Paul Rogers (D-Fla.), chairman of the Commerce subcommittee with clear air jurisdiction, says the lobbying on this bill is the heaviest "in my 23 years in Congress".

Unlikely alliances have been formed on both sides. Supporting the legislation that came out of the subcommittee - which itself makes some changes in the 1970 act - are environmental groups, consumer groups, the American Medical Associations, the nation's governors, mayors, home builders and realtors and such other groups as the Council of Shopping Centers and Association of Chain Drug Stores. The Carter administration is also for the bill.

On the opposite side, favoring assorted further amendments to the 1970 legislation are the United Auto Workers, AFL-CIO, Chamber of Commerce, Business Roundtable, auto industry, automobile dealers, utilities and assorted major oil, steel and chemical companies.

The 1970 act was deliberately "technology-forcing", meaning the technology did not exist then to meet all the standards Congress set. The idea was that Congress would give ground later if it had to, and it had done so several times, such as granting delays on auto pollution.

Though national output of most major pollutants has leveled off, it is hardly news that many parts of the country still have dirty air. In 1970 the country was divided into 250 air quality regions and now all but 29 meet federal ambient air quality standards. But those 29 have a total population of about 50 million. They include the major urban areas, in some of which, because of increased industry or use of the auto, pollution has gotten worse.

The most controversial section of the current bill involves autos.

In 1970 the auto industry was told that by 1975 it would have to reduce emission from its three major pollutants, hydrocarbons, carbon monoxide and nitrogen oxides, by 90 per cent. Environmental Protection Agency test show selected model 1977 cars have reduced hydrocarbon and carbon monoxide emissions by nearly 80 per cent. Nitrogen oxide is the pollutant most fought over because it is difficult to control and because its health hazard is greatest. When it combines with other chemicals it forms nitrosamines, potent cancer-causing substances. It is also a key element in photochemical smog. It has been reduced 43 per cent.

But environmentalists argue that only prototype cars are tested, not those leaving the assembly line, so no one knows how well fleets of cars actually do, and no one knows how long the emission control system works. It is known that a city like Washington, whose pollution comes mainly from cars, still exceeds ambient air quality standards.

The auto industry has been granted several delays from Congress in meeting the 90 per cent standard, which, without this bill, would be required on 1978 model cars going into production in a few weeks.

Everyone agrees the auto industry must have a one-year delay and the pending House and Senate bills both grant it. But what happens after that will be the most hotly debated issue on the floor this week.

The auto industry, backed by the UAW, is fighting for an amendment sponsored by Reps. John Dingell (D-Mich) and James Broyhill (R-N.C.) that would phase in slightly weaker emission standards over a longer period than the committee bill.

Rogers and White House contend there would be damaging health effects because of the weaker standards and delay.

Almost as important, Rogers says the Dingell amendment would strike authority for assembly line testing and state testing at the time of sale to see whether cars meet standards. Rogers claims about 50 per cent of 1975 cars are exceeding carbon monoxide standards.

Dingell, on the other hand, says the committee proposal would lead only to "statistically insignificant improvements in the nation's ambient air quality," and provide "no proven benefits to health." In addition, Dingell says the tighter emission standards would cause a 5 to 10 per cent fuel penalty, and an additional $350 per car with an extra $100 in maintenance costs. If cars cost more and consumers buy fewer automobiles, jobs could be lost, Dingell said - and it is this jobs issue which brought in the UAW on the side of the auto industry. It is the UAW which gives the Dingell proposal its clout on the Hill.

Rogers disputes Dingell's fuel penalty figures, and points to some foreign cars which meet auto emission standards with a fuel savings.

Realtors, homebuilders, hotel-motel associations and state and local officials want the auto industry to clean up, because if it doesn't, it means their areas won't meet ambient air quality standards and industrial and commercial expansion will be limited.

EPA has already issued so-Called "trade-off" regulations which require for a new industry to come into a dirty air area, a present industry must reduce pollution by the amount the new industry would add.

However, the committee has relaxed this controversial policy, by saying if a state can show "reasonable progress" toward attaining cleaner air, new industry could come in.

The final controversy centers on whether areas now cleaner than the standards require can get significantly dirtier.

In 1972, the Supreme Court held that the law requires pervention of significant deterioration, but did not say what that meant.

In the bill, Congress tries to define that ruling by setting up three classes for the six pollutants covered by air quality standards.

National Parks and wilderness areas over 25,000 acres would have to remain "pristine" or in a Class I designation. It would be left up the states whether to put smaller parks and monuments and wildlife areas in Class I or a more relaxed Class II.

Class III would allow about 50 per cent more pollution than an area has now and, according to the committee, would not prevent coal-fired power plants.

Finally the bill requires new plants use "best available technology" which utilities say mean expensive scrubbers on smokestacks. Environmentalists again argue this is "technology forcing".

Of the significant deterioration policy, which would largely affect Western states, one critic said last week, "this is a no-growth policy. They don't want to pollute the East, but they don't want the West to get dirtier either."