Urban noise vs. nature’s calm: A Swiss study of noise annoyance and the role of residential green

Abstract

Noise exposure has been linked to numerous adverse health effects. However, research has demonstrated the beneficial role of natural green on human well-being and stress restoration. This study aimed to elucidate the association of exposure to road traffic noise (RTN) and residential green with annoyance, and evaluate the relative importance of road traffic compared to other noise sources based on two surveys: a cross-sectional field study in the city of Zurich (n = 1,111), and a nationwide survey across Switzerland (n = 2,229). Exposure-response curves of long-term noise annoyance regressed on residential green (normalized difference vegetation index, NDVI) and road traffic noise exposure at the participants’ home (day-evening-night level L_den) were established. Results from the nationwide sample showed a significant negative association of residential green with noise annoyance: Increasing greenness from the 5^th to 95^th percentile NDVI was associated with strongly reduced RTN annoyance, corresponding to an equivalent sound level reduction of 4 dB. For the city of Zurich sample, this difference amounted to a non-significant 3 dB. In a general assessment of noise sources, survey respondents in both samples rated noise from construction sites as similarly annoying as from road traffic. The results underscore a potentially beneficial role of urban green in decreasing RTN annoyance, and pinpoint relevant noise sources beyond road traffic. Our findings highlight current issues of source-specific noise within communities and suggest the need for policies that integrate noise reduction and green space expansion, enhancing restorative environments and thus mitigating noise impacts for public health.