The nexus of nature-based solutions and sustainability in cities: vegetation’s impact on particulate matter capture and traffic noise reduction

Abstract

Road traffic is among the primary sources of air pollution and environmental noise in urban spaces. Prolonged household and occupational exposure to air and noise pollution has been associated to various health problems and premature mortality. Mitigating these health risks relies on reducing exposure to urban pollution. This study analyzes the role of vegetation in capturing particulate matter and in reducing traffic noise. The study was conducted in Guimarães, Portugal, and involved collecting samples of particulate matter that had settled onto leaf surfaces within two green walls, as well as conducting noise measurements into two sites adjacent to green walls and at two sites with blank walls. Results indicated that vegetation could have an important role in capturing particulate matter and reducing traffic noise. For example, the daily average removal of Hedera helix was 94.47 mg/m² per day. In terms of noise, ¾ of the Leq measurements in front to green walls were lower than in sites in front to blank walls, reaching 1.9 dBA in the case of a wall covered with Ficus pumila. Therefore, green walls are effective nature-based solutions that should be used to mitigate the environmental and health impacts in urban spaces.