Air pollution

Urban planning to reduce air and noise pollution

Urban environments provide many benefits and opportunities to residents, but there are also hazards associated with living in cities. Two of the most persistent issues are air and noise pollution, which often originate from the same sources. Reducing one often means reducing the other, leading to measurable health improvements and more attractive urban spaces in general.

Mitigation efforts in European cities have so far been largely insufficient to reduce air and noise pollution below specified guidelines. New approaches to urban planning are required to make a meaningful difference.

This article is a brief summary of the Sweco Urban Insight report “Wholesome Sir, Serene Cities – Reduced Noise and Air Pollution in Urban Areas.” Please explore the full report for more information, citations and additional conclusions.

Often the same sources of both forms of pollution

Solutions to noise and air pollution problems are complex because they originate from human activities that are often part of a vibrant, urban culture. These activities include transportation and construction, as well as shopping (delivery of goods), restaurant visits, leisure activities and more.

Reducing or removing these sources is difficult. Such changes take time and call for access to better alternatives. Long-term strategies are required for transportation systems, production and construction methods, in favour of quieter, more environmentally friendly solutions.

This makes it all the more important to identify solutions to pollution both in existing urban areas and when planning new urban areas.

Air pollutants – a major health issue

The negative effects of noise pollution on our health has also been studied extensively via e.g. noise mapping and is well documented. Noise exposure from road traffic and industry can cause sleep disturbance, and associated increased risk of hypertension and cardiovascular disease, that can indirectly reduce life expectancy. It has also been shown to have a significant negative effect on the cognitive performance of schoolchildren – and it is assumed that other noise sources can lead to the same negative health effects.

Noise mapping performed by the European Environmental Agency (EEA) has determined that noise exposure levels remained relatively stable between 2007 and 2012. However, levels are likely to increase in the future due to continued population growth in urban areas and increased road and air traffic.

Key findings from EEA noise mapping:

Strategic noise maps show that approximately 75 million citizens living in European urban areas are exposed to noise levels above L_den 55 dB, which is the threshold level recommended by World Health Organization (WHO).
Road traffic noise is the foremost source of noise.
Based on available noise mapping data reported by European countries for 2012, an estimated 11 million urban residents are annoyed by road noise and 5 million suffer from sleep disturbance.
It is similarly estimated that reported road noise exposure causes 500,000 cases of hypertension, 43,000 cases of heart disease and 10,000 premature deaths every year.

Solution: Integrating air quality in Urban planning

Road traffic is the dominant noise source in the city and a large contributor to air pollution. Heavy vehicles, which emit 10 times the noise of passenger cars, contribute to noise exposure in particular. Good traffic planning removes traffic or reduces traffic noise in sensitive areas.

This may involve reducing or banning heavy vehicles inside the city centre, restricting the speed to 30 km/h for all vehicles, banning studded tyres and older diesel vehicles and, in the longer term, only allowing e-cars. Good conditions for cyclists and public transport will also help reduce polluting traffic. These solutions are efficient as they limit noise and pollution at the source, but they are complicated to implement due to their impact on traffic.

Another possible measure may be to require delivery of goods to shops by smaller vehicles. When integrating air quality in urban planning, it is crucial to understand the anticipated effects of using the various tools and the way in which different sources contribute to the total pollution level.

Solution: Technological developments

Technological solutions to reduce air and noise pollution are available but further development and combination of solutions could improve the efficiency.

Noise screens are very efficient (up to 10 dB noise reduction) behind the screen at ground level but have limited effect in city centres with multi-level blocks of flats located close to the street.

Low-noise asphalt has an audible effect and is a popular measure due to its low cost and simple implementation, although it has become less effective over time. The lifetime average noise reduction of low-noise asphalt is 1–2 dB.

For all vehicles, more pollutants are emitted as speed is reduced to under around 80 km/h. Stop-and-go driving, which is very common in cities, gives rise to unnecessary emissions and noise pollution. Intelligent traffic regulation can be helpful in this regard.

Improving flue gas cleaning at power plants and the fuel efficiency of cars will reduce emissions of air pollutants and CO₂.

Using electric busses can reduce emissions and noise from public transport in the city and electric buses are already in use in many cities across Europe, although in small scale. A new charging system where the bus is partially charged, by use of a pantograph at the end stations, is currently being tested.

Garbage collection is another aspect of urban planning that affects noise and air pollution. Garbage lorries are known to be very noisy, and non-electric models contribute to air pollution. The use of garbage lorries can be reduced through implementation of a vacuum waste system.

Solution: calm areas

The High Line Park, Manhattan, New York. Garden on roof top

It is becoming more difficult to find calm urban areas as population density increases, and there is a need for new ideas for calm spaces – spots where urban citizens can experience a moment of peace and tranquillity. Calm areas can provide significant health benefits to citizens. Such areas can be found in city parks, between blocks of flats, in courtyards, gardens, leisure areas, etc.

Methods of creating calm areas in the city include designating low speed limit zones, restricting heavy vehicles and encouraging bicycle use and road sharing. With road sharing, roads are designed to be shared by motorised vehicles, cyclists and pedestrians. In other words, road sharing requires traffic calming. This can be achieved through proper road design – one example is the placing of obstacles on the road to slow traffic.

Additional details on road sharing are presented in the Urban Insight Report “Urban Mobility on a Human Scale.”

Solution: Noise insulation and dwelling ventilation

In existing urban areas with canyon-like streets and heavy traffic, the best solution may be to reduce noise and air pollution inside people’s homes.

Noise insulation, or building protection, is an efficient solution to reduce indoor noise exposure from all noise sources, both day and night. It can make a perceptible difference to urban residents and can reduce sleep disturbances. The solution should be combined with energy optimisation and low-noise ventilation to reduce the need to open windows for cooling purposes or to let in fresh air.

Report: WHOLESOME AIR, SERENE CITIES – REDUCED NOISE AND AIR POLLUTION IN URBAN AREAS

For additional information, conclusions and citations, please refer to the full report. This Urban Insight report addresses the relationship between the sources and levels of air and noise pollution and provides recommendations that can make a perceptible difference to urban citizens and improve quality of life in urban areas.

To the report