[Show abstract][Hide abstract] ABSTRACT: A survey of environmental tobacco smoke (ETS) controls in California office buildings was carried out to obtain information of the type and distribution of ETS controls in office buildings and to evaluate the effectiveness of various ETS controls. A total of 118 smoking areas in 111 county and city buildings were inspected to collect information on the type of ETS controls. Only 31% of the smoking areas inspected were physically separated from nonsmoking areas with full floor-to-true-ceiling walls, 25% exhausted air to the outside, and 38% did not recirculate air to non-smoking areas. A total of 23 smoking areas and their adjacent non-smoking areas in 21 buildings were monitored for nicotine and fluorescent particulate matter (FPM). A tracer gas, sulfur hexafluoride (SF6), was released in smoking areas to measure the air leakage from smoking areas to adjacent non-smoking areas. The measurements of nicotine, FPM, and SF6 have shown large variations of the effectiveness of ETS controls. The least effective type of smoking area studied were open areas with no physical barriers between smoking and nonsmoking areas, no exhaust to the outside and no return air separation. On the contrary, smoking rooms with three ETS controls (i.e., physical separation, exhaust to outside, and no air recirculation) were the most effective design in containing ETS within smoking areas.