Systems and methods for analyzing a diffusion trend of a diffusible substance. The systems may obtain a plurality of sets of reference information relating to the diffusible substance from a plurality of devices respectively, each of the plurality of sets of reference information at least including a time point when a corresponding device detects the diffusible substance and a location where the device detects the diffusible substance. The plurality of sets of reference information may correspond to a same or a substantially same time domain. The systems may determine the diffusion trend of the diffusible substance based on the plurality of sets reference information.