14: Air quality and noise
Integrating air quality and traffic noise management
14.1 Air pollution and noise are often emitted from the same sources (notably road traffic) and locations of poor air quality can coincide or overlap with locations subject to high noise levels. Even where they do not, poor air quality at one location and high noise levels at a neighbouring location may be related through the way in which traffic is managed across the wider area. In aiming for the most beneficial outcome for members of the public, it is important to seek measures that both improve air quality and reduce noise levels - for example speed restrictions - and avoid measures that worsen one while seeking to improve the other. Local authorities should ensure that an integrated approach to managing air quality and noise is taken across all departments, and when working with external partners.
14.2 Directive 2002/49/ EC on assessment and management of environmental noise aims to define a common approach to avoid, prevent or reduce on a prioritised basis the harmful effects, including annoyance, resulting from exposure to environmental noise. The Directive is transposed by the Environmental Noise (Scotland) Regulations 2006. The regulations assigned the role of competent authority for preparing noise maps and action plans under the Directive to the Scottish Ministers.
14.3 The Scottish Government has produced strategic noise maps and noise action plans for major roads, major railways, Aberdeen, Dundee, Edinburgh, Glasgow agglomerations and for Edinburgh, Glasgow, Aberdeen and Dundee Airports, all as required by the Directive. Local authorities may be aware of additional areas not covered by the Directive requirements where transportation noise is known to be an issue.
Traffic noise and health
14.4 According to preliminary results from a World Health Organisation study  , air pollution and noise are estimated to be the leading factors influencing the environmental burden of disease in Europe. In 2010 the Health Protection Agency (now part of Public Health England) published Environmental noise and health in the UK  which concluded that:
Environmental noise is a problem in the UK today and many people are concerned about its possible effects on health. In terms of wellbeing we have little doubt that a significant number of people are adversely affected by exposure to environmental noise. If it is accepted that health should be defined in such a way as to include wellbeing then these people can be said to suffer damage to their health as a result of exposure to environmental noise. There is increasing evidence that environmental noise, from both aircraft and road traffic, is associated with raised blood pressure and with a small increase in the risk of coronary heart disease.
14.5 In 2011 the World Health Organisation published Burden of disease from environmental noise: Quantification of healthy life years lost in Europe  . The report estimated that at least one million healthy life years are lost every year from traffic related noise in western Europe, specifically:
- 61,000 years for ischemic heart disease;
- 45,000 years for cognitive impairment in children;
- 903,000 years for sleep disturbance;
- 22,000 years for tinnitus; and
- 654,000 years for annoyance.
14.6 Scottish Transport Appraisal Guidance  ( STAG) contains information on assessing the impact of environmental noise in relation to new transport projects. Tools developed by bodies such as the UK Government's Interdepartmental Group on Costs and Benefits  and the European Environment Agency  may be of use in providing indicative monetary valuations of noise related health effects. This guidance can be used in cost benefit analyses for options appraisal, provided that the uncertainties and assumptions behind the methodologies are taken into account. Transport Scotland and Scottish Government are working with local authorities to develop and apply an appropriate Appraisal and Test of Reasonableness tool for ranking effective Noise Management Area interventions.
Air quality action planning and noise
14.7 As stated elsewhere in this guidance, air quality action plans must include evidence that all available options have been considered in relation to cost effectiveness and feasibility. Cost beneficial measures should be given priority, although there will be circumstances when cost effective measures are required for working towards air quality objectives.
14.8 Whenever air quality action plans prioritise measures in terms of costs and benefits, traffic noise should receive due consideration, qualitatively if not quantitatively. Special consideration should be given to noise management areas identified by the noise action plans, and any other areas where a local authority considers traffic noise to be a matter of concern, particularly where proposed air quality measures may potentially impact on noise levels. Such an impact could occur over a wide area, for example if diverting traffic from one location leads to noise increases elsewhere. Therefore, when developing an action plan, local authorities should bear in mind that there may be consequential effects of introducing a specific measure.
14.9 Authorities must make a judgement in each case as to whether the impacts of action plan measures on traffic noise need to be quantified or whether they can be treated qualitatively when prioritising measures. The noise assessment should reflect local circumstances and should not be disproportionate to the scale of change proposed.
14.10 Certain measures, particularly those concerned with reducing local traffic flows, may benefit both air quality and noise, although in some cases this may only hold true when speeds are not permitted to increase. Other potential measures that can reduce both air pollution and noise include restrictions on heavy vehicles, reducing speeds on motorways and dual carriageways, and strategies to increase the separation between the source and sensitive receptors, for example by building a bypass. However, measures to lower average speeds of traffic in urban areas, whilst usually benefitting noise, may increase air pollutant emissions. Modelling may be required to determine the optimum public health outcome for a given locality. The level of detail sought should sensibly reflect the scale of changes proposed.
14.11 Containment of air pollution and noise through the use of tunnels, cuttings or barriers may worsen air quality for road users. This should be taken into account when considering options. Ensuring compliance with EU air quality limit values or domestic objectives may result in negative noise outcomes in some instances. Where this occurs, it should be recorded clearly so as to inform the prioritisation of any future noise improvement initiatives.