Abstract
The study examined the air pollution tolerance indices (APTI) of six plant species around Otorogun gas plant in Ughelli-South Local Government Area of Delta State. Four physiological and biochemical parameters, which are leaf relative water content (RWC), Ascorbic acid content (AA), total leaf chlorophyll (TCh) and leaf extract pH were used to compute the APTI values. The result showed order of tolerance as Emilia Samtifolia
(1.49%)> Manihot esculenta (2.19%)> Elaesis guineensis (2.41%)> Impereta cylindrical (25.56%)> Eupatorium Odoratum (35.17%)> Psidium guayava (45.11%).