Assessing the air pollution tolerance index (APTI) of trees in residential and roadside sites of Lahore, Pakistan

Abstract Industrialization and extensive use of automobiles cause air pollution which indicates the inability of trees plants due to changes in their biochemical and physiological processes for absorbing the air pollutants. Air Pollution Tolerance Index (APTI) is an important indicator for determining the ability of trees plants for their efficient ability for controlling air pollution. To estimate it and its effects a comparitive study of the air pollution tolerance index was examined in 14 species of plants between residential areas (University of the Punjab) and roadside areas (orange train line). To calculate the APTI value, four physiological and biochemical parameters—ascorbic acid, relative water content (RWC), pH, and chlorophyll concentration of leaf samples—were integrated. Present study results reveal that the plant tolerance against pollution is site specific, and that integrating a number of biochemical parameters give more accurate results as compared to single. Results show that Alstonia scholaris show maximum and Magnifera indica show minimum APTI values in residential areas while Magnifera indica shows maximum and Bougainvillea glabra shows minimum APTI value in roadside areas. Present study results show that plants with higher APTI values are tolerant of pollution, whereas those with lower APTI values are susceptible to it. Thus Plants with more APTI values are tolerant and use as a sink to control pollution in urban and industrial sites.