The studies on the concentration of aero anion in some south China forest recreation areas showed: (1) The aero anion concentration has differences in different forest types. (2) In forest surroundings, the correlation between aero anion concentration with temperature and moisture are significant. (3) Water body has different effect on aero anion concentration in forest recreation areas. (4) There have been aero anion daily variance and yearly variance. (5) The...