Current World Environment

Vehicular traffic is one of the major contributors to accumulate dust on plants grown alongside roads. Plants intercept tons of dust, absorb noise and serve as acoustic screens on busy highways. Vegetation contributes in reducing dust concentration in environment by acting as a sink for air pollutants. Taking this into account, the  present study was conducted on National highway- 22 from Parwanoo to Solan, falling in Solan district of Himachal Pradesh, India. Specifically, four plant species namely Grewia optiva Drummond ex Burret,  Toona ciliata M. Roem, Melia azedarach L. and Woodfordia floribunda (L.) Kurz of uniform size, age, spread and common in occurrence on both sides of the highway were selected for the study.  Dust accumulation on leaves of selected plants was estimated during three main seasons (Rainy, Winter and Summer) of the year. Samples were collected from two horizontal distances (0-5 m and 5-10 m) from both sides of the road. Results showed that dust accumulation on the leaves ranged from 0.0083 g m^-2 in T. ciliata to 0.0597 g m^-2 in G. optiva and followed the descending order G. optiva > W. floribunda > M. azedarach > T. ciliata. Season wisethe examined plant species followed the descending order winter > summer > rainy season. Plants grown at a distance of 0-5 m accumulated higher dust on their leaves as compared to 5-10 m distance from the road. Due to surface characteristics of twigs, bark and foliage of the plants particulate matters are captured by them and remain there for extended time period. From the results of this study, it could be inferred that the air quality in urban/ arid areas can be improved by planting firstly the species G. optiva and W. floribunda along road sides of similar highways to national highway-22.