Evaluation of Some Tree Species for Refinement of Air Quality in Urban Areas by Estimating Air Pollution Tolerance Index and Anticipated Performance Index

Green vegetation in urban areas is affordable and environmentally friendly because it can help reduce air pollution. The selection of appropriate plant species for a green belt is essential. This study assessed nine plant species in four distinct locations of urban areas of the Siddharthanagar municipality, i.e. industrial, roadside, residential, and garden areas in winter and monsoon seasons. The Air Pollution Tolerance Index (APTI) was computed based on the biochemical characteristics that are significant to each plant species. Additionally, for these plant species, the dust load and anticipated performance index (API) were computed by integrating APTI values with additional biological and socioeconomic factors. Dust content of Tectona grandis was higher in polluted (industrial and roadside areas) and moderately polluted areas (residential areas) than in less polluted areas (garden areas) in both winter and monsoon seasons. Among all plant species, the most tolerant to air pollution were Azadirachta indica (winter), Dalbergia sissoo (winter and monsoon), and Magnifera indica (winter). Ficus benghalensis, Ficus religiosa, Magnifera indica, and Dalbergia sissoo were found to be tolerant of air pollution based on API and APTI. Hence, plants with higher APTI and API values, such as Ficus benghalensis, Ficus religiosa, and Magnifera indica, can be used for minimizing the air pollution in urban areas of Nepal, while plants with lower APTI and API values (Saraca asoca) can be used as bioindicators. This study will provide valuable recommendations for selecting plant species for shelterbelt development in urban industrial areas of tropical countries, considering factors such as plant composition, climatic conditions, and air pollution levels.