Visible light communication (VLC) systems are heavily dependent on a line-of-sight (LoS) path between a user device (UD) receiver and the VLC transmitter. As a result of this requirement, the performance of VLC systems is strongly limited by their susceptibility to signal blockage. Towards network management, it is useful to quantify the extent to which these blockages occupy transmission time. This article, therefore, attempts to model the momentary impact of VLC downlink (DL) obstructions caused by human movements. The shape of potential human blockers that could interrupt the DL is approximated by either a rectangular prism or a cylinder. This work obtains the closed-form expression between interruption duration, angle of obstruction, and blocker size. We proceed to carry out simulation to ascertain the effect of dimensions, of the two types of blockers, on the time duration of LoS link obstructions.