The following diagrams show the path of air mass reaching Hong Kong for the next three days (13 - 15 March 2011). It can be seen that the air mass reaching Hong Kong mainly come from the Taiwan Strait and Luzon Strait.
  

Figure 1. Trajectory of air mass reaching Hong Kong at 8 a.m. 13 March 2011

Figure 2. Trajectory of air mass reaching Hong Kong at 8 a.m. 14 March 2011

Figure 3. Trajectory of air mass reaching Hong Kong at 8 a.m. 15 March 2011