Methodological proposals for improved assessments of the impact of traffic noise upon human health

Background, aim and scope Several methodological shortcomings still hinder the inclusion of transport noise as an established impact category within life cycle assessment (LCA). Earlier attempts to quantify the health damages caused by traffic noise yielded valuable results from an academic point of view, but these were of limited use in the context of everyday LCA practice. An enhanced understanding of traffic noise emission models coupled with a straightforward choice of indicators could lead to faster, more accurate assessments of health impairment due to traffic noise whose results would fittingly serve the purposes of policy makers and the information needs of the general public alike. This article aims to propose the guidelines for such assessments. Materials and methods The assessment method presented takes an incremental approach in similar fashion as previous work in the field done by R. Müller-Wenk. An explanation is provided of how the assumption of linearity leads to a substantial overestimation of noise level increments attributable to additional vehicles, and subsequently to a misjudgement of overall health impacts due to traffic noise. Hence, an alternative calculation method allowing for better accuracy in the computation of noise level increments is proposed. This method can be easily applied, needless of a specific traffic noise emission model. A more detailed method, based on the state-of-the-art Improved Methods for the Assessment of the Generic Impact of Noise in the Environment (IMAGINE) traffic noise emission model, is also described. This method is to be applied to large-, medium- and small-scale assessments where variations in traffic flow or composition can be reasonably predicted or measured. In the proposed methodology, health impairment due to traffic noise is not aggregated in DALY (disability-adjusted life years). Rather, the results are given in terms of the ‘number of annoyed persons’, which is derived from the synthesis curves relating noise exposure to annoyance presented by Miedema and Oudshoorn. The calculation procedure and data needs to do this are explained. Moreover, the validity of taking the number of annoyed persons as a proxy for overall health impairment due to traffic noise—and the main benefits of doing so—are discussed. Performing the attribution of impacts on a per vehicle-kilometre basis can lead to impact misrepresentations whenever an incremental approach is taken. A different attribution scheme, which t