Relationship between noise complaints and urban density across cities of different levels of density: a crowd-sourced big data analysis

Background Exposure to noise is an increasingly serious public health problem globally. The frequency of noise complaints is a useful indication in terms of adverse effects of noise on mental health, such as anxiety and annoyance. This study aimed to investigate the relationship between noise complaints and urban density across cities of different levels of density, which is an important urban development and planning factor. Methods Each noise complaint, with time and location labels, was reported by crowds via email, phone call, or app. We used complaint data in 2019 (England and London, UK) and in 2018 (New York, NY, USA) from England Public Health Profiles, London borough open data, New York open data (retrieved Aug 30, 2021), with Geographic Information Science technique and Spearman correlation analysis. We analysed the noise complaints in England, with a mean density of 18·36 people per hectare (2·5–97·5th percentile values 0·69–117·22), with a focused examination in London (89·79 people per hectare, 15·37–208·22), and compared with New York, a higher density city (94·05 people per hectare, 0·07–348·54). Findings There were 359 231 noise complaints included in the analysis in England, 77 518 in London, and 436 692 in New York. Noise complaint rates had strong relationships with urban density in England (coefficient 0·550, 95% CI 0·446–0·635), London (0·549, 0·455–0·630), and New York (0·557, 0·523–0·589). Significant positive coefficients were also observed when categorising the samples according to noise level bands. The relationships were linear in England and London, and non-linear in New York. When the density reached around 230 people per hectare, the correlation became weaker and the slope reduced. Interpretation As expected, we found that noise complaints increased with increasing urban density. In a very high-density city such as New York, the contribution of density factor to noise complaints seemed to be less significant, although further comparison with high-density cities in Asia would be interesting. These findings could be used to identify areas with more serious public health issues related to noise nuisance, and could lead to more effective noise-management and planning strategies in areas of different densities—eg, setting up different noise control criteria according to densities, and using and protecting greenery in urban areas. Funding European Research Council Advanced Grant (number 740696) on Soundscape Indices.