Open Access. © 2020 A. Gagliano et al., published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0 License Noise Mapp. 2020; 7:57ś73 Research Article Antonio Gagliano, Francesco Nocera, Andrea Cicero, Luigi Marletta, and Gianpiero Evola* Mitigation of environmental noise in urban streets through lightweight transparent screens https://doi.org/10.1515/noise-2020-0005 Received Sep 16, 2019; accepted Mar 20, 2020 Abstract: Noise pollution is one of the main environmental stressors in urban areas. In particular, strong noise pollu- tion can be experienced at nighttime in downtown areas with intense anthropic activities: here, dwellers may sufer from disturbance to their rest, which induces stress and ś in turn ś adverse efects on health. Usually, local authorities implement actions to tackle noise pollution, e.g. limiting the time allowed for outdoor events. However, these measures are often inadequate be- cause the noise annoyance comes directly by the shouting of people spending time outdoors till late night. In this framework, this study proposes a procedure to op- timize the shape of customized lightweight transparent noise screens that can be applied to façades in order to re- duce noise disturbance in urban canyons. The case study of the łmovidaž area in the downtown of Marina di Ragusa (Southern Italy) is discussed to test the applicability of the proposed procedure. The results of this analysis allow defning the shape and the size of the noise screens that minimize the noise an- noyance perceived by residents. The proposed mitigation approach can be applied in cities afected by signifcant noise pollution. Keywords: noise pollution, noise screens, urban canyons, genetic algorithms, parametric design *Corresponding Author: Gianpiero Evola: DIEEI, Univer- sity of Catania, Viale A. Doria 6, 95125 Catania, Italy; Email: gevola@unict.it Antonio Gagliano, Luigi Marletta: DIEEI, University of Catania, Viale A. Doria 6, 95125 Catania, Italy Francesco Nocera: DICAr, University of Catania, Via Santa Sofa 64, 95123 Catania, Italy Andrea Cicero: Gillieron Scott Acoustic Design, 130 Brixton Hill, SW2 1RS London, United Kingdom of Great Britain and Northern Ireland 1 Introduction Environmental noise, generated by human activities, is a relevant environmental issue in densely populated ar- eas [1]. Indeed, European Union estimates that around 20% of European population sufer from noise expo- sure. Moreover, according to a study conducted by the World Health Organization, environmental noise has been ranked in six European cities as the second main envi- ronmental stressor that afects public health, and the ex- pected trend is that noise exposure is going to increase in Europe compared to other stressors [2]. The composition of urban noise is complex, due to a wide range of sounds originated by diferent sources, such as transport (road trafc, aircraft and railway noise), com- mercial and entertainment activities [3]. It is commonly known that road trafc noise in urban areas severely af- fects people’s health and lives [4], since it often exceeds tolerance levels. However, in city centres and in crowded touristic areas, where the concentration of anthropic activ- ities is rather high, very high noise levels may also be ex- perienced because of recreational activities (the so-called movida), especially during nighttime. This causes sleep disturbance for residents, which in turn may even induce serious consequences on wellness [5]. Some studies in the literature have already tackled the issue of recreational noise in urban areas. As an exam- ple, Ottoz et al. [6] examined the case of some łmovidaž districts in Milan and Turin. By means of online question- naires, residents reported that the high noise levels, com- ing from shouts and music due to outdoor events or to public places, afect their sleep, everyday life and health; they were also concerned about estate depreciation and ex- penses to mitigate the problem. The sound level measure- ments in some samples confrmed what the residents de- clared, showing very high sound pressure levels in the res- idents’ homes between 11 p.m. and 02 a.m., both with open and closed windows. On the other hand, Ballesteros et al. developed a pro- cedure for the noise characterization of leisure areas, and investigated three leisure areas of a big-sized city (Madrid) and one of a medium-sized city (Cuenca) in Spain [7]. The