Comparative study of roadside avenue trees as bio-indicators of air pollution in and around Mumbai, India: A case study

With rapid increase in urbanization followed by industrialization compounded due to ever-exploding population in the past few decades there is a steep rise in contamination of one of the most vital abiotic factors of the environment i.e., the air. In these circumstances, the clean and green measures to monitor and control air pollution have become inevitable. Air Pollution Tolerance Index (APTI) is one such index for indicating the extent of the plants to withstand air pollution. This includes analysis of physiological and biochemical parameters like total chlorophyll content, ascorbic acid content, pH of the leaf extract and relative water content of the leaves. In this study, the plants selected are mature tree species like Polyalthia longifolia, Putranjiva roxburghii, Alstonia scholaris, Delonix regia and Peltophorum pterocarpum from Mumbai and its surrounding regions. According to the Air Pollution Tolerance Index (APTI) values, plants can be classified as tolerant, intermediate, sensitive and highly sensitive. The tolerance of the plants studied in the decreasing order is as follows P. roxburghii > P. pterocarpum > D. regia > P. longifolia > A. scholaris. Species selected on the basis of their APTI values can then be used as bio-indicators of air pollution and in its mitigation for green belt development in urban areas.