Air pollution due to tobacco smoke and its effects on employees were investigated in 44 workrooms. For this purpose, the concentrations of CO, NO, NO2, nicotine, and particulate matter were determined, and 472 employees were interviewed about annoyance and irritations. The mean values of the concentrations of the components due to tobacco smoke are: CO = 1.1 ppm, NO = 32 ppb, NO2 = 24 ppb, nicotine = 0.9 micrograms/m3, particulate matter = 133 micrograms/m3. One third of the measured CO values exceeds a critical threshold of 2 ppm CO due to tobacco smoke. One quarter of the persons reports eye irritations at work. One third of the employees qualifies the air with regard to smoke at the workplace as bad. Forty percent of the interviewed persons are disturbed by smoke. The majority of the employees is in favor of a separation into smoking and non-smoking rooms. This seems to be the most appropriate preventive measure for the protection of nonsmokers at work.