In recent years, air cleaners are often used because of increasing interest in room air quality. However, there is currently no unified method for determining the removal effectiveness of air-cleaners. Here, we report the results of experiments on five type of domestic air cleaner units in a experimental room, using ETS(Environmental Tobacco Smoke). This study was carried out to determine the removal effectiveness of air cleaners on suspended particulate matter evaluated employing an index of equivalent clean air rates(ECAR). The results showed that the removal rates of suspended particulate matter were 59.1〜125.7(m^3/h) for 0.3μm particles, and 115.5〜188.7(m^3/h) for 0.5μm particles respectively with fan-filter units. The rates were much lower for the electro-static collector type unit without fan : 3.9(m^3/h) for 0.3μm particles, and 14.8(m^3/h) for 0.5μm particles respectively
