The contribution of hedge in decreasing pollution levels in Rome

Over the past two decades the anthropogenic greenhouse gas emissions have increased contributing to emphasize the effects of global climate change. Cities account for more than 71% of the energy related to global greenhouse gases which is expected to rise up to 76% by 2030. The problem is emphasized in those urban areas where vehicular traffic poses a major impact by emitting combustion gases. It has been hypothesized that CO2 emissions from road traffic worldwide will increase by 92% between 1990 and 2020 affecting the environment, health and economy. After air pollution, noise pollution reduces the quality of the urban environment because it affects human health unfavorably, both physically and psychologically. Noise pollution in cities is generated through different sources, such as road traffic, construction and commercial activities, industries and airports. In recent years, road traffic has played a dominant role in causing environmental noise. Among urban greening, hedges are ubiquitous elements of many public, commercial and residential landscapes. The mechanism of noise attenuation in plants is due to the capacity of leaves to absorb acoustic energy by transferring the kinetic energy which vibrates air molecules in a sound field to the vibration pattern of the leaves. The aim of this research was to analyze structural traits of different hedge types: Laurus nobilis L, Nerium oleander L, Pittosporum tobira (Thunb.) Aiton, and Pyracantha coccinea M. Roem. (Fig. 1) traditionally used for green infrastructure in Rome in order to quantify their CO2 sequestration and noise attenuation capability.