Air pollution tolerance of trees in an educational institute in Delhi

The present study evaluated air pollution tolerance index (APTI) of 21 major tree species in an educational institute being classified as a sensitive area with respect to air pollution. Magnifera indica, Ficus religiosa, and Ficus benghalensis were classified as tolerant species having high Ascorbic acid (AA) content which helps maintain good chlorophyll levels despite lower Relative water content (RWC) values for Ficus spp. More than 3/4^th of the species had good RWC values attributing to tolerance. It was observed that the trees with broad leaves and thick canopy had higher chlorophyll concentration compared to the trees with compound leaves and cone-type canopy. Ascorbic acid concentration chiefly governed the tolerance to air pollution. About 38% of the studied plants were classified as moderately tolerant to tolerant, and the rest as intermediate tolerant or sensitive which may be a cause concern if the concentration of pollutants of air rises. Based on APTI values, tolerant and moderately tolerant plants are recommended for green belt development and air pollution attenuation.