House and Senate conferees on clean air legislation have reached tentative agreement to escalate the war on industrial sources of smog by extending federal pollution controls to such small emitters as dry cleaners, bakeries and furniture makers in the most polluted cities, congressional sources said yesterday.

The new controls, negotiated by House and Senate staffers over the weekend, are part of a larger agreement setting out the powers and obligations of states to curb excessive levels of smog in nearly 100 cities.

Conferees are expected to give formal approval to the agreement this week, boosting prospects for passage of a clean air bill before Congress adjourns Oct. 5. The provisions for industrial smog constitute the largest section of the House and Senate bills, which originally prescribed very different approaches to cleanup.

It was not immediately clear how the agreement will sit with the White House, which had worked out weaker provisions with Senate leaders as part of a larger compromise. Senate conferees accepted the House bill without significant changes.

The agreement seeks to strengthen the hand of states trying to bring their communities in compliance with health standards for air pollutants. The Clean Air Act of 1970 required states to submit compliance plans to the Environmental Protection Agency and implement them by 1975. But the EPA approved overly optimistic plans and then failed to use its leverage to assure attainment of the standards.

Conferees agreed on new progress goals for smog, a serious respiratory irritant and the most recalcitrant of urban pollutants. States would have to bring about smog reductions of 15 percent within six years and 3 percent annually until the goal is attained.

The agreement gives states stronger tools to combat industrial sources of smog, which are responsible for one-third of the pollution in the dirtiest cities. Current law requires pollution controls on plants emitting more than 100 tons a year of hydrocarbons or nitrogen oxides, the two main ingredients of smog.

Under the agreement, controls would be imposed on emitters of 10 tons in Los Angeles, including bakeries, printers and dry cleaners. The threshold would rise to 25 tons in areas the law defines as "severely" polluted areas, such as New York, and 50 tons in "seriously" polluted areas, including Washington.

The agreement also imposes potential growth curbs. It requires that any emissions from new plants would have to be offset by reducing emissions from existing sources. The more polluted a city, the higher the ratio of offsets would be required.

Controls also would be required for the first time for consumer products that emit hydrocarbons, such as paints, solvents and nail polish.