P3410Traffic noise and ischemic heart disease - review of the evidence for the WHO environmental noise guidelines for the European region

Abstract

Background: In Europe about 65 million people are exposed to noise levels exceeding EU guideline for noise outdoors at the façade. In contrast to many environmental factors, exposure to traffic noise is increasing, both as a result of rising traffic volumes and continued urbanization. In 2013 the Regional Office for Europe of the World Health Organization (WHO) initiated a revision of the Guidelines for Environmental Noise. Previous Guidelines were issued by WHO in 1999 and based primarily on studies published until 1995. Since then substantial new evidence has appeared on serious adverse health effects related to long-term exposure to traffic noise, in particular with regard to cardiovascular disease. Purpose: As part of the development of new WHO Environmental Noise Guidelines a systematic review was performed on cardiovascular and metabolic effects of environmental noise. The evidence regarding traffic noise exposure and ischemic heart disease (IHD) is summarized here. Methods: A total of more than 600 relevant publications since the year 2000 were identified, but only 61 met pre-set criteria enabling quantitative risk assessment. More than a third of these concerned IHD related to noise from road traffic, railways and/or aircraft. Meta-analyses were performed expressing risks in relation to a 10 dB increment in noise exposure and using reported confidence intervals to estimate variance. Random-effect models were fitted and heterogeneity between studies was evaluated as well as publication bias. Quality of the evidence was assessed using a modification of the GRADE criteria. Results: The most comprehensive evidence was available for road traffic noise and incidence of IHD, where 8 longitudinal studies were available, primarily of cohort and case-control design. A combined relative risk of 1.08 (95% confidence interval 1.02-1.15) was estimated per 10 dB increase in road traffic noise exposure based on a total of 7451 cases of IHD. There was no clear indication of heterogeneity between studies or of publication bias. Supporting evidence came from studies on prevalence and mortality of IHD with estimates of 1.24 (95% CI 1.08-1.42) and 1.05 (95% CI 0.97-1.13) per 10 dB, respectively. The quality of the evidence on traffic noise and IHD was considered moderate. For aircraft and railway positive associations were generally observed but the number of studies was more limited and the quality of the evidence considered poorer than for road traffic noise. Conclusions: Combined analyses of longitudinal epidemiological studies on road traffic noise and IHD show statistically significant increases in relation to exposure. The studies are generally of high quality but non-experimental and the overall quality of the evidence is considered moderate. Given the effects on stress hormone levels and sleep disturbance a causal association between traffic noise and IHD appears plausible.