The Consumer Product Safety Commission staff said yesterday that a new type of kerosene heater on the market has achieved a "technological breakthrough" in safety, reducing certain hazardous air pollutants by between 50 percent and 90 percent.

"It's a dramatic advance," said Sandra Eberle of the commission's chemical hazards program.

At least one firm, Toyotomi America Inc., is marketing the new "multi-stage" heater. The Toyotomi heater, called a toyostove, is imported from its parent company, Toyotomi Kogyo Co. Ltd. in Japan. Toyotomi Kogyo also manufactures body parts for Toyota cars.

Eberle said that the CPSC has not yet surveyed the entire kerosene heater market in its study and acknowledged that there could be other firms that market the new heater. The new multi-stage heaters are more expensive than conventional ones, with prices ranging from $160 to $219, compared with $70 to $130 for the old-style models, the agency said.

Indoor air pollution from unvented kerosene heaters has been a controversial issue in past years. Government safety experts have warned consumers not to use the heaters without opening a window or door for ventilation.

But the commission staff said yesterday at a briefing that some of the new heaters produce so little pollution that they could be used even in a closed room, although that is still not recommended.

The primary emission hazard associated with kerosene heaters has been nitrogen dioxide, a chemical that can cause breathing problems and that has been associated with the cancer-causing chemicals, nitrosamines. Carbon monoxide, which can be deadly, also has been measured in amounts that could lead to significant ill health in some conditions.

The new heaters have a first stage of blue flame, which reduces the nitrogen dioxide but produces carbon monoxide. The carbon monoxide then flows into a second chamber, where a hotter white flame burns the carbon monoxide, producing more heat and cutting the emission of that gas.

The CPSC is now encouraging an industrywide, voluntary nitrogen dioxide standard to reflect advances in reduced emissions possible with the new technology.

"The results from the advance technology heaters were impressive," Eberle said. "Nitrogen dioxide emission rates for both the radiant and convective heaters were reduced by 75 to 80 percent over those tested in 1983." Carbon dioxide emission rates were reduced between 50 percent and 90 percent depending on the type of heater, Eberle added.