House and Senate conferees reached agreement on acid rain controls early yesterday, bridging longstanding regional divisions to paint the last broad strokes of a larger plan to scour the skies clean by the turn of the century.

The agreement, designed to cut 10 million tons of acid rain emissions by the year 2000, meant only a few issues remain for the conference to resolve. The most contentious is a House plan for $250 million in relief for workers displaced by new clean air laws. Although the relief provision has been called "veto bait" by the White House, it has strong support among key congressional negotiators eager to complete the first revision of clean air laws in 13 years.

With Congress hoping to adjourn this week, conference leaders worked to sweep up the remaining issues last night and send to both houses by midweek their complex bill that seeks to end urban smog, cut 90 percent of cancer-causing and toxic emissions by industry and halt acid rain damage.

The legislation is expected to ring up costs of $25 billion a year for industry, which managed to block the most far-reaching measures with a massive lobbying effort. The bill is still expected to force major changes in the way industry operates and in its products: It calls for less-polluting cars, trucks and buses; new blends of gasoline with additives derived from corn; fast development of substitutes for ozone-depleting chemicals used in everything from air conditioners to foam cushions; and cleaner steel plants, oil refineries and power plants.

Such disparate interests have long kept Congress from reforming the outdated Clean Air Act, even as dangerous levels of smog were reached in 100 cities, factory pollution elevated the risk of cancer to nearby communities and acid rain from power plants killed trees and streams in New England.

Yesterday's acid rain agreement, forged at 5 a.m., culminated 14 weeks of negotiation in the House-Senate conference. Like the rest of the bill, it was a patchwork of compromises delicately balancing regional and political interests.

The broad objectives of acid rain control have not been in question since President Bush framed the debate by introducing his bill in June 1989. Both houses passed and conferees quickly approved Bush's proposal to impose a nationwide cap of 8.9 million tons a year on utility emissions of sulfur dioxide, the principal ingredient of acid rain. The cap, to be reached in 2000, would lower power plant emissions 10 million tons from 1980 levels.

There was also little debate that the biggest emission cuts would come from plants in the Midwest and Appalachia that burn cheap, high-sulfur coal without anti-pollution devices. Those plants got around local limits on sulfur dioxide by building towering smokestacks that eject pollution high into the air, where it turns acidic, wafts to the Northeast and falls in rain, snow and dust.

The central question became how to force huge reductions by those plants without bankrupting their ratepayers and killing the high-sulfur coal industry.

The solution was a system of pollution credits invented by the administration to soften the blow. Under the plan, dirty utilities would receive a ton of credit for every ton they cut below their prescribed limit. The credits could be sold to other utilities seeking to expand operations beyond their limit, and the cash could be used to pay for technology to scrub sulfur from plant emissions.

Plants equipped with such "scrubbers" could still burn high-sulfur coal, thus saving thousands of mining jobs.

But both houses massaged the system to construct a tangled nest of incentives for scrubber use and concessions to appease representatives of "clean" states and utilities with special problems.

In the conference, House negotiators agreed to accept the simpler Senate version on condition midwestern plants receive more credits and that certain utilities get special treatment.

"The politics finally came together," said Rep. Gerry Sikorski (D-Minn.), a House conferee and sponsor of the acid rain legislation. "Every region can feel there's fairness."

Despite the tradeoffs on acid rain, the issue was easy compared to the fight over auto pollution, the main source of urban smog. At the center was Rep. John D. Dingell (D-Mich.), head of the House delegation and patron saint of the auto industry in his Detroit-area district.

Negotiations dragged for a month as Dingell, working to extract concessions for Detroit, surprised the Senate with a proposal that was not in either bill: He sought to restrict the right of states to adopt and enforce California's limits for autos, strictest in the nation.

As Dingell could have anticipated, the offer ran into resistance from Senate conferees known for their opposition to state preemption. Then, as suddenly as he introduced the measure, Dingell withdrew it -- for a price. Senate conferees agreed to several proposals for auto pollution controls that were weaker than those in the Senate bill.

As a result, new standards for tailpipe emissions of smog-generating compounds -- 39 percent reductions for hydrocarbons, 60 percent for nitrogen oxides -- are to be phased in by 1996, a year later than the Senate bill. And conferees accepted the House formula for determining the need for another round of cutbacks early next century, instead of a Senate provision considered more likely to trigger a second round.

The conference directive for "reformulated gasoline" -- a cleaner-burning blend capable of reducing smog-forming compounds in the nine dirtiest cities by 15 percent in 1995 and 20 percent in 2000 -- would kick in three years later than in the Senate bill.

Conferees dealt an even heavier blow to the Senate's plan for ultra-clean fuels made from natural gas or its derivative, methanol. A provision for such gasoline alternatives in all new passenger cars sold in the nine smoggiest cities as early as 1995 was eliminated after fierce lobbying by the oil and auto industries.

Instead, negotiators accepted a House proposal for a pilot program in California and extended the right of opting into the program to the 27 dirtiest cities. The California program calls for annual sales by 1998 of 150,000 cars that can run on fuels whose emissions meet standards twice as tough as the 1996 standards for the rest of the nation's fleet. In 2000, the number of cars would double to 300,000 a year and the fuel standard would tighten.

But some experts believe the standard could be met by using reformulated gasoline and improved anti-pollution devices on cars, making unnecessary a new generation of fuels that environmentalists view as the best long-run solution.

The conference agreement on airborne toxics, which are so dangerous that even small doses can cause death or serious disease, resulted in the first federal controls on coke-oven emissions and municipal incinerators, and sets forth the first guidelines to prevent accidents in chemical plants.

But a lobbying blitz by the utility industry persuaded lawmakers to exempt the toxic discharges of power plants, the primary sources of such dangerous metals as mercury and cadmium.

Most of the week-long negotiation was consumed by a fight over the steel industry's coke ovens, which expose nearby communities to a higher risk of cancer than any other industrial pollutant. Dingell and Rep. Dennis E. Eckart (D-Ohio), both with steel plants in their districts, fought to extend the deadline by which coke ovens have to diminish the cancer risks to downwind residents.

Conferees agreed to extend the deadline to 2020 but required increasingly stringent technology to reduce leaks.