In this seminar, the speaker gives a brief introduction of the human thermal plume dominated zone (HTPDZ) around the human body created by the human thermal plume. He then addresses the negative and positive role of the HTPDZ on the contaminant cross transmission between person to person. He will also use examples to explain how the HTPDZ affects the contaminant cross transmission under different conditions, contaminant cross transmission in vertical unidirectional ventilated protective isolation environment and aircraft cabin environment.