The association between road traffic noise and depressed mood among different ethnic and socioeconomic groups. The HELIUS study.

BACKGROUND: Although there is growing evidence that depressed mood is affected by road traffic noise, previous results are not fully consistent. Furthermore, to our knowledge, no previous research has assessed ethnic and socioeconomic inequalities in the association of noise exposure with depressed mood. OBJECTIVE: To investigate the association between road traffic noise with depressed mood and to determine to what extent this association varies between ethnic and socioeconomic groups. METHOD: We investigated cross-sectional data collected between 2011 and 2015 from 23,293 HELIUS participants (18-70 years) living in Amsterdam. Our study included five different ethnic groups (Dutch, Moroccan, Turkish, South-Asian Surinamese and African Surinamese origin). All respondents were linked by their residential postal code to geographic data on road traffic noise levels (24 h noise average in A-weighted decibels [dB(A)]). Noise was categorized into five categories (45-54 dB(A), 55-59 dB(A), 60-64 dB(A), 65-69 dB(A), ≥70 dB(A)) and high noise exposure was defined as noise levels ≥65 dB(A). Depressed mood was defined as a sum-score of ≥10 on the 9-item Patient Health Questionnaire (PHQ-9). Logistic regression was performed to assess the relationship between road traffic noise and depressed mood. Multilevel analyses were used to take into account the clustering of observations within neighbourhoods. Lastly, logistic regression analyses were applied to estimate relative risks for depressed mood per different ethnic and socioeconomic groups exposed to high noise exposure ≥65 dB(A) compared to <65 dB(A). Analyses were adjusted for individual- and neighbourhood-level confounders. RESULTS: Exposure to ≥70 dB(A) compared to the reference group of 45-54 dB(A) showed a significant positive association with depressed mood (OR: 1.65, 95% CI 1.10, 2.48). Participants exposed to 60-64 dB(A) showed a significantly lower odds ratio of 0.82 (95% CI 0.70, 0.97) compared to the reference group. We observed no differences between ethnic groups in the association of high noise exposure ≥65 dB(A) with depressed mood. Regarding socioeconomic groups, results were different for the medium-low educated group and unemployed group only. CONCLUSION: This study adds new evidence regarding a positive association between high road traffic noise exposure and depressed mood in residential settings. We found no evidence for systematic ethnic or socioeconomic inequalities regarding this association.