Stanford Univ, Stanford Linear Accelerator Ctr, Stanford, CA 94309 USA
; IHEP, Beijing, Peoples R China
; LBL, Berkeley, CA USA
The sudden drop of the beam lifetime and bursts of the background radiation were detected in many machines and associated with microscopic dust particles. We present the model of the dust particle dynamics explaining the long time of the dust events observed in the PEP-II B-factory and BEPC-II machines.