SACRAMENTO - Up to 150,000 light trucks, vans and other oversized vehicles a year will be equipped with passenger car style anti-smog equipment as a result of tighter tailpipe standards adopted today by the California Air Resources Board (ARB).

The standards, phased in over the 1995 and 1996 model years, would reduce emissions of smog-forming hydrocarbon and nitrogen oxide, as well as carbon monoxide, by 223 tons per day, compared to the 15,000 tons emitted by all vehicles in the state every day.

Vehicles covered by the new standards, however, would have their emissions cut from 26 to 75 percent, depending on the model and its curb weight.

Besides approving the tighter tailpipe limits, the ARB also doubled the amount of time that manufacturers must meet them, from 50,000 miles to 120,000 miles, after research showed that the vehicles are driven an average of 140,000 miles during their road life and emit 70 percent of their pollution past the 150,000 mile mark.

Vehicles covered by the new standards, such as oversized pick-up trucks, vans, ambulances, tow trucks, small school buses and small motor homes, have met standards closer to those imposed on bigger commercial vehicles that carry very heavy loads. Research has shown, however, that most of these vehicles are often used for everyday commuter traffic, just like passenger cars.

Emission standards for these heavier vehicles have not kept pace with those for passenger cars over the last 10 years. As a result, these vehicles amount for as much as 9 to 13 percent of all automotive emissions, even though they represent only 6 percent of the vehicles registered in the state.

The lightest vehicles in this class, trucks with curb weight of up tp 3,750 pounds, will meet emission standards that are identical to California passenger cars, will meet emission standards that are identical to California passenger cars, which are the world's lowest-polluting. Heavier classes of vehicles that carry bigger payloads will meet progressively more lenient standards.

To meet the standards, truck makers are expected to use more sophisticated emissions systems that have been introduced on passenger cars over the last decade. That includes wider use of fuel injection and computerized ignition systems so that engines burn fuel more efficiently, as well as better catalytic converters.

The heaviest trucks covered by the standards, with curb weights up to 14,000 pounds, are likely for the first time to use a type of catalytic converter that has been widely used on passenger cars since 1980.

The ARB cost estimates for the standards are $61 for the lightest trucks that need the fewest modifications and $390 for the heaviest trucks that will require more modifications.

ARB Chairwoman Jananne Sharpless noted that the air quality benefits from the new standards are significant, especially in reducing nitrogen oxide, a key component of smog and many other air quality problems.

 "As we have tightened emission standards for other types of cars and trucks, both lighter and heavier, emissions from this group have grown.

 "Very sophisticated and effective anti-smog systems are being used on other types of vehicles because of ARB standards," she noted. "It makes sense to take advantage of that technology to reduce pollution from these vehicles, too."