Abstract: Air pollution is among the most challenging problem in today’s world. In this study, Air Pollution Tolerance Index (APTI) was calculated for four different plants (Panicum maximum,Eleusineindica,XanthosomamafafaandAmaranthusspinosus) found growing along four busy roads (Aba road, East/West road , Ikwerre road and NTA road) in Obio/Akpor local government area and control (IkwerreNgwo) in Etche local government area in Rivers State, Nigeria. The computed APTI results obtained from four biochemical parameters(relative water content, ascorbic acid, leaf extract pH and chlorophyll) showed that the APTI of the test plants recorded remarkable changes as the values obtained in the experimental sites were higher than the control site. The APTI values in the experimental sites (4 roads) were in the range of P. maximum (7.4 – 8.04); E. indica (7.3 – 8.2); X. mafafa (7.2 – 7.9); and A. spinosus (7.2 – 8.0) as against the control (< 6.2) showing that all the test plants studied were sensitive to pollution. Thus, these plants can be used as a better indicator of air pollution in an environment.