Assessment of Air Pollution Tolerance Index (APTI) and Expected Performance Index (EPI) of Plants along Nsukka, Enugu Road, Nigeria

Abstract

Air pollution is a worldwide ecological problem that threatens human health through harmful emissions as vehicular exhaust emission. There is a need to examine ecological role of plants growing around major roads to identify their susceptibility and resistance towards air pollutants. Air Pollution Tolerance Index (APTI) and Expected Performance Index (EPI) of some plants growing along Nsukka - Enugu road in Enugu State, Nigeria were estimated to explore plants’ ability to absorb air pollutants. Twenty-eight plant species comprising herbs, shrubs and tree species were sampled and determination of APTI used combined biochemical parameters measurements. The APTI results showed that herbs are sensitive with APTI range of < 7 to 11.91, shrubs are mostly moderate tolerant with range of 9.38 to ≤ 17.43 while trees species are tolerant that ranged from ≥ 10.58 to ≥ 23.26 at t ≤ 1.51, p>0.05 in the experimental and control sites respectively. Based on APTI grades, Rauvolfia. vomitoria (11.91) had highest sensitive index and Erigeron canadensis (6.45) had the least, Persea americana (16.11) had highest moderate tolerant index and Ricinus. communis had the least while Terminalia. catappa (23.26) produced the highest tolerant index and Gmelina arborea (17.50) had the least in the experimental site. The EPI revealed that plants can be categorized as fit, very fit and unfit for plantation and those under ‘excellent to best’ performer category can be highly recommended as ‘very fit’ for plantation to control air pollution. Dacryodes edulis (94.74%) was in the ‘Best’ performer category and the best recommended species for plantation planting to monitor and control air pollutants.