Ventilation systems touted as an alternative to banning smoking in indoor public spaces fail to eliminate soot and carcinogens and can contaminate the nonsmoking areas of buildings, researchers say.

The Associated Press reported Nov. 1 that a study of three restaurants using ventilation systems described as being efficient enough to comply with local antismoking laws found that, in one case, airborne contaminants were higher in the nonsmoking restaurant side than in the bar where smoking was allowed.  In another cases, air-pollution levels were higher than they were before supposedly less-efficient air-cleaning systems were replaced.

Lead researcher James Repace found that the displacement systems, which use cool air to push hot, smoky air out of a room and are touted as state-of-the-art, were difficult to maintain and were not working properly.

"I don't think it is possible for somebody to come up with a system that works," Repace said. "You'd need tornado-like ventilation."

Price Industries Inc., a manufacturer of displacement ventilation systems, said the systems are "not intended to be a panacea." The U.S. Surgeon General, in a recent report on secondhand smoke, said that, "separating smokers from nonsmokers, cleaning the air, and ventilating buildings cannot eliminate exposures of nonsmokers to secondhand smoke."