To the Editor.
—Borland et al1 present data from a survey of reported workplace exposures to environmental tobacco smoke (ETS) among nonsmoking Californian adults. Exposure was assessed by the question, "During the past 2 weeks has anyone smoked in the area in which you work?" Information was also obtained about the type of smoking policies at the respondent's workplace. The authors concluded that "the only way to protect nonsmokers' health is with a smoke-free worksite."This conclusion does not appear to be justified by the reported data. The mere presence of a smoker within a nonsmoker's workplace for an undetermined length of time during the 2 weeks prior to a survey does not warrant a conclusion that smoking should be prohibited. Borland et al neither determine the actual level of exposure to ETS nor assess the working conditions of the population being studied. Instead, the authors simply categorize the