Evaluation of air pollution tolerance index of selected tree species to combat air pollution in urban areas of Mettupalayam, Tamil Nadu, India

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Urban air pollution remains a critical environmental issue, and afforestation offers a sustainable approach for its mitigation. The present study evaluated the Air Pollution Tolerance Index (APTI) of 20 tree species from urban areas in and around Mettupalayam by analyzing key biochemical parameters including ascorbic acid (AA), total chlorophyll (TC), leaf extract pH, and relative water content (RWC). Based on APTI values, species were categorized as Sensitive (1–10), Moderately Tolerant (11–17), and Tolerant (17–29). Among the parameters, ascorbic acid showed a strong positive correlation with APTI (r = 0.923***). A multiple linear regression model (R² = 0.9728) confirmed AA as the most influential factor. Polyalthia longifolia (27.79), Peltophorum pterocarpum (25.43), and Tamarindus indicus (18.48) were identified as highly tolerant species. These findings suggest that selecting tree species with high APTI can enhance urban green cover and contribute significantly to air pollution abatement.