Central Department of Botany, Tribhuvan University, Kathmandu, Nepal 

Air pollution is major threat to urban areas. Aerial parts of pants mainly leaf surface acts as a sink for deposition of air pollutants in the urban and industrial environment and is considered as ecologically sustainable cost-effective strategies to mitigate adverse effects of air pollution. In this condition, assessment of biochemical characteristics total chlorophyll content, leaf extract pH, ascorbic acid content and relative water content and computed air pollution tolerance index. Air pollution tolerance index (APTI) offers simple tool for screening and identifying plants that tolerate air pollution. Five plants commonly growing in the roadside of Lalitpur district were selected for assessing the biochemical characteristics and air pollution tolerance response. There were significance differences in biochemical characteristics between polluted and non-polluted sites.  APTI indices of Buddleja asiatica Lour., Ficus religiosa L., Lecosceptrum canum Sm, Tecoma stans (L.) Juss. ex Kunth. and Nyctanthes arbor-tristis L. were assessed and compared with the plants grown in non-polluted sites of Lalitpur to analyze the response to air pollution. Among the plants evaluated, high APTI of >11 was recorded in F. religiosa indicating that the plant is tolerant to air pollutants at the collected sites. B. asiatica recorded lowest APTI of 8.30, indicating that this plant is sensitive to air pollutants and can be used for biomonitoring the air pollution.