The releasing properties of negative air ions of tourmaline contained polypropylene (PP) and ethylene propylene diene terpolymer/polypropylene (EPDM/PP) composite films under varying testing conditions were investigated in this study. It is interesting to note that the Cion- values of EPDM/PP/tourmaline specimens tested at varying, conditions are significantly higher than those of the PP/tourmaline specimens with the same loadings of tourmaline powders. Moreover, all Cion- values of PP/tourmaline and EPDM/PP/tourmaline film specimens tested at dynamic impact mode are significantly higher than those of the corresponding specimens tested at static mode but the same temperature. A beneficial temperature effect on Cion- values of the PP/tourmaline and EPDM/PP/tourmaline film specimens tested at static and dynamic impact conditions was found. To understand these interesting negative air ion properties of PP/tourmaline and EPDM/PP/tourmaline film specimens, energy dispersive X-rays analysis of the tourmaline powders, scanning electron microscope morphology, and tensile property analysis of the PP/tourmaline and EPDM/PP/tourmaline film specimens were performed. Possible reasons account for the interesting negative air ion properties of the PP/tourmaline and EPDM/PP/tourmaline film specimens are discussed. (C) 2008 Wiley Periodicals, Inc.