Long-term exposure to traffic noise and mortality: A systematic review and meta-analysis of epidemiological evidence between 2000 and 2020.

We aimed to update the evidence-base of long-term noise exposures from road, rail, and aircraft traffic on both non-accidental and cardiovascular mortality. A systematic review and meta-analysis were conducted following PRISMA guidelines. The literature was searched using PubMed, Scopus, Web of Science, and EMBASE for the period between January 01, 2000 and October 05, 2020. 13 studies were selected for final review. The risk of bias and overall quality of evidence was evaluated using a pre-defined list of criteria. Risk estimates from each study were converted into per 10 dB higher of L for each traffic source. Inverse-Variance heterogeneity (I-Vhet) meta-analysis was used to pool these individual risk estimates, along with assessment of heterogeneity and publication bias. Sensitivity analyses include using random-effect model and leave-one-out meta-analysis. Subgroup analyses by study design and noise exposure assessment were conducted to explore potential sources of heterogeneity. For road traffic, the pooled relative risk (RR) per 10 dB higher L for mortality from non-accidental causes was 1.01 (95% CI: 0.98, 1.05) (5 studies, I = 78%), CVD was 1.01 (95% CI: 0.98, 1.05) (5 studies, I = 41%), ischemic heart disease (IHD) was 1.03 (95% CI: 0.99, 1.08) (7 studies, I = 46%), and stroke was 1.05 (95% CI: 0.97, 1.14) (5 studies, I = 62%). The overall quality of evidence for most meta-analyses was rated as very low to low, except for CVD or IHD mortality, for which the quality of evidence was rated as moderate. A possible threshold of 53 dB was visually suggested for CVD-related mortality from road traffic noise in the trend analysis. For aircraft noise, pooled estimates were based on fewer studies and varied by mortality outcomes. Evidence of long-term exposure to traffic noise on mortality remains weak except the association between road traffic noise and IHD mortality. High-quality longitudinal studies are required to better characterise mortality effects of traffic noise.