To the Editor.
—In 1988 I participated in a press conference in New York to present the findings of a survey of tobacco smoke exposure in restaurants compared with offices. We informed reporters that the study and the press conference itself were sponsored by the tobacco industry.Our conclusions were that of the various components of tobacco smoke, nicotine, particulates, carbon monoxide, and the like, only nicotine was source-specific and this was the only substance that could be used as a marker of airborne tobacco concentrations. Our analyses of 46 offices and 49 restaurants yielded average airborne nicotine concentrations of 4.3 μg/m3 of air and 6.2 μg/m3, respectively. These figures can be compared with the permissible exposure limit of 500 μg/m3 specified by the Occupational Safety and Health Administration for workplace exposure.Skeptics doubted the accuracy of our data, suggesting bias as a result of the source