Abstract
For the purpose of re-examination of Koch's Dropping Method (Koch method) which is simple and useful for continuative management of airborne bacteria in a dental hospital, climatic, environmental and airborne bacteria were measured using an SY type pinhole sampler method (SY method) and a Koch method for 3 years (1988, 1990, 1991) in five clinics at Asahi University dental hospital. Analytical points were as follows : 1. Floating airborne bacteria colonies (SY method) were estimated with the climatic and environmental factors, and dropping airborne bacteria colonies (Koch method) by multipule regression analysis. The effect of addition of dropping airborne bacteria colonies on the accuracy of the equation of multipule regression was evaluated. 2. A correlation between the number of airborne bacteria by SY method and by Koch method was made, and a predicted section of a value of dropping airborne bacteria colonies corresponding to the clean standard value (0.2 CFU//) of floating airborne bacteria colonies was estimated. The following results were obtained, 1. The addition of dropping bacteria colonies to floating airborne bacteria colonies increased the estimated accuracy of the equation of multipule regression. It is concluded that the Koch method is useful for simple air pollution monitoring. 2. The correlation between the number of airborne bacteria obtained by the SY method and by the Koch method had a high coefficient of 0.439-0.606 (p<0.01). The estimated value of dropping airborne bacterial colonies corresponding to the clean standard value of floating airborne bacterial colonies was 0.755-1.333 CFU and the upper limit of a predicted section with 95% reliability was 2.161-4.116 CFU. Therefore, the clean standard value of dropping airborne bacterial colonies was about 4.1 CFU, and the Koch method is useful for simple air pollution screening. Thus, we confirmed that the Koch method is useful for continuative management of airborne bacteria in a dental hospital.
