Road traffic in European cities exposes 60 million people to unhealthy noise levels

A study carried out by the Barcelona Institute for Global Health (ISGlobal), a centre promoted by the "la Caixa" Foundation, has evaluated noise levels from road traffic in 749 European cities and their impact on health. The results, published in Environment International, show that nearly 60 million adults are subjected to noise levels generated by vehicles that are harmful to health. Meeting WHO noise recommendations would prevent more than 3,600 deaths from ischaemic heart disease each year.

Road traffic is the main source of environmental noise. Previous studies have linked environmental noise to a range of adverse health effects: sleep disturbance, annoyance, cardiovascular and metabolic diseases, adverse effects at birth, cognitive impairment, as well as poor mental health and well-being. Prolonged exposure to road traffic noise can provoke a sustained stress reaction, resulting in the release of stress hormones, increased heart rate and blood pressure and vasoconstriction, which can eventually lead to chronic diseases such as cardiovascular disease, depression and anxiety disorders.

For this study, data for European cities were obtained from the Urban Audit 2018 dataset. Road traffic noise exposure was estimated using noise maps produced by countries and cities under existing European legislation (the Environmental Noise Directive) or available from local sources (such as municipalities and research institutions). Where data were lacking for cities within a country, a predictive model was developed and applied to estimate exposure to road traffic noise. Data on mortality from different causes for the year 2015 were extracted from the Eurostat database.

The results show that more than 48% of the 123 million adults (20 years and older) included in the study endure noise levels above the WHO recommendation. It should be recalled that the WHO recommends that the average noise level over 24 hours should not exceed 53 decibels (or 53 db Lden). In terms of national capitals, the percentage of the population exposed to levels above the recommended level ranges from 29.8% in Berlin to 86.5% in Vienna, and from 43.8% in Madrid to 60.5% in Rome.

Based on previous studies that established associations between noise and mortality from ischaemic heart disease, the research team estimated that complying with WHO recommendations would prevent more than 3,600 deaths each year.

It was also estimated that more than 11 million adults would be suffering a high level of annoyance as a result of traffic noise. Annoyance is defined as the result of repeated disruption of everyday activities such as communicating, reading, working or sleeping. Such annoyance goes beyond mere inconvenience, as it can increase stress and eventually degenerate into various health problems.

"Our results provide for the first time a comprehensive picture of European cities and provide a clearer understanding of why transport noise is the second leading environmental cause of adverse health effects in Western Europe, after particulate air pollutants," explains Sasha Khomenko, ISGlobal researcher and first author of the study. "Even so, we are convinced that the true health impact of traffic noise is much higher, as the lack of city-level data limits the health effects we can assess and consequently leads to an underestimation of the impact. In addition, the available data has only allowed us to analyse the population exposed to more than 55 dB Lden, when the WHO recommendation is 53 dB Lden, and we suspect that adverse effects could occur even with exposure to lower noise levels," she adds.

The team encountered methodological difficulties due to the heterogeneity of the available data and the quality of the data. Each of the noise maps used was subjected to a qualitative assessment, with most of them falling into the low or medium quality categories and less than 17% considered to be of good quality.

"The European directive on environmental noise made strategic mapping mandatory, but it did not set out a methodology or guidelines, so the results have been mixed. Since January 2019 we have a common methodology for EU member states, so we can expect to see much more comprehensive and accurate health impact assessments of traffic noise in the coming years," says Mark Nieuwenhuijsen, head of ISGlobal's Air Pollution and the Built Environment programme and senior author of the study.

This study is part of the Burden of Mortality in Europe project, which has so far produced rankings of mortality attributable to air pollution and green space, respectively, in European cities. However, due to the disparity of methodologies and sources of traffic noise data, it was felt that the results obtained for the different cities analysed are not comparable. Consequently, a ranking was not produced on this occasion, although all the data has been made available on the project website, where the values of the 749 cities analysed can be consulted.

More information at https://isglobalranking.org/