抄録
In order to predict and control asbestos concentration in rooms with asbestos-containing materials it is necessary to know its generation rate caused by direct or indirect disturbance of the sprayed asbestos surface. Various kinds of experiments were carried out in a room with a ceiling containing asbestos. Some disturbances occurred on the moistened floor expecting no redispersion of asbestos might occur from it. Main results obtained were as follows : 1. Hitting a ball to asbestos ceiling caused 1.4-2.1×10^4 fibers' dispersion in each trial. 2. Blowing by a fan caused 8.3-22×10^4 fibers per minute with its direct appliance to the ceiling and 1.2-23×10^5 f/min with one to the floor respectively. 3. Sweeping the ceiling by broom directly, the most violent disturbance, caused 1.4×10^7 f/min. 4. Moderate walking caused 1.2×10^5 f/min, but in case of wet floor asbestos generation decreased down to 3.5×10^4 f/min. 5. Not only asbestos generation from the sprayed surface, but its redispersion by disturbance from the floor should not be neglected. 6. Because of its airborne characteristics good ventilation may be effective to control indoor asbestos contamination, whether there is any disturbance or not.
