It is well known that smoking generates harmful air pollutants. With smoking in buildings as well as in the streets prohibited, the need for smoking rooms has emerged. In this study, particle and CO contamination in a 63.6 m3 smoking room was experimentally investigated using Korean tobacco. Tobacco smoking was artificially simulated using a smoking machine. The number and size distribution of particles ranging from 10-420 nm and 0.25-32 μm were measured using a Nanoscan (TSI model 3910) and a portable aerosol spectrometer (Grimm model 1.109), respectively. CO concentration was also monitored using an IAQ monitor (Graywolf IAQ-Xtra 610). Four tobaccos were simultaneously smoked in each experiment, and the experiment was repeated four times. Maximum CO concentrations of 7-10 ppm were observed and high concentrations of particles (176,000-1,115,000 particles/cm3 for 10-420 nm, 3,700-5,200 particles/cm3 for 0.25-32 μm) were also monitored. The dominant size of tobacco particles was about 100 nm in diameter. Keywords : CO, Contamination, Particle, Smoking room, Tobacco