Abstract
This paper reports the measurement results of settled particulate matter contaminated with fungi in air ducts before and after air duct cleaning. This study also gives a method for estimating the number of settled particles on the inner surface of air ducts using the index of areal coverage of settled particles. The main results are shown as follows: (1) Settled particles increase at an exponential function annually. Although there are about 42000 fungi contaminated in one gram weight of settled particles, they are almost removed by air duct cleaning together with settled particles. (2) The size distribution of settled particles both in supply and return air duct seems to be lognormal. (3) The number of settled particles can be estimated using "areal coverage index" of particles, and the estimated values correspond with the measured ones.
