Air Pollution
Clean Air for Kids

Sustainable Transport & Air Quality


An effective transport system is vital for economic well-being and good quality of life. However, there is widespread concern that the continuing growth of transport is damaging to the environment. The total number of vehicles on the UK's roads is approximately 29 million. This is projected to increase by 17% by the year 2010. Road vehicles in the UK are major contributors to emissions of nitrogen oxide (NOX), carbon monoxide (CO) and black smoke. The impacts of vehicle exhaust emissions include acid deposition and air pollution, human health effects, global climate change and noise pollution. Growth in transport is also damaging to the efficient functioning of the economy (through road congestion). The distances travelled during a car journey are becoming shorter as cars are used to reduce time: 60% of journeys made by car cover distances of under 5 miles. A sustainable transport policy, to safeguard air quality and human health, will require a thorough integration of numerous modes of transport.

The Percentage of Journey Made by Various Modes of Transport (1997-1999)
and the Proportion of Distance Travelled (1998-2000).

























Sustainable Transport in the UK

In the Sustainable Development Strategy for the UK, the Government has acknowledged that it will need to take action to control the rate of traffic growth, improve the environmental performance of vehicles and increase public awareness about the environmental impacts of pollutant emissions from transport. The best approach to promoting a more balanced transport policy will be an integrated approach with both "carrot" and "stick" measures to get people out of their cars. If people are to reduce their dependence on the car, they must be provided with alternatives that are affordable.

Reducing the Need to Travel

Emphasis needs to be placed on reversing the trend of population dispersal outwards from urban areas. By effective land-use planning, activities (including work, shopping and leisure) are brought closer together, reducing journey distances to a level where travel on foot and by bicycle becomes more popular. To facilitate this, urban centres need to be made more attractive, and the quality of urban living needs to be improved.

Car Pooling

"Car-pooling" is the term used to describe regular journey sharing between a group of drivers, usually to and from work. This leads to a reduction in the number of cars in city centres and is also a more economical way to travel.

Reducing Road Space

Experience suggests that traffic tends to expand to fill available road space. This process also works in reverse. As road space is reduced, traffic shrinks so the overall level of service is roughly unchanged. This process is termed "traffic evaporation". One of the most effective ways of avoiding traffic growth is simply not to provide for it. Further transfer from car to public transport can occur if the latter is allowed access to large areas denied to car traffic. Pedestrianisation also increases the retail turnover of town centres, contrary to popular belief.

Charging for Road Space and Parking

This provides a way of charging motorists for some of the social and environmental costs of car use not reflected in petrol or maintenance costs. Charges can be varied according to peak usage. Unfortunately, the requirement for government legislation for road pricing creates a significant barrier to introducing such a scheme. It is possible that such legislation may be made available to local authorities in the next few years. Higher parking charges may deter people from taking cars into city centres and make public transport seem more attractive.

Improving Public Transport

A shift to non-car-based travel will only occur when the quality of public transport service is improved. This will largely include rail, light rail (tram) and bus services. The introduction of bus lanes and improved transport information services are beginning to make public transport more attractive and speed up journey times. The cost of public transport needs to be reviewed to make services more attractive.

The Manchester Metro

Cycling can often be the quickest way to make short journeys. There are presently numerous cycle tracks in towns and cities, but the improvement and expansion of these routes could encourage more people to cycle. Improving cycle parking facilities at convenient locations could assist this.


Walking is a sustainable mode of transport that is available to all at no cost. The safer the walking environment the better, and hence the introduction of pedestrianisation in city centres has increased the number of walkers. As with cycling, walking is also a healthy way to travel as it increases physical fitness.

Promoting More Efficient Motoring

Fuel efficiency varies with speed. Above 50mph, fuel consumption increases rapidly. By maintaining slower speeds, fuel is conserved, and less carbon dioxide is emitted. In addition, cars driven economically (with reduced acceleration, braking and cornering speed) can save 10% of car fuel.

Traffic Management Schemes

Traffic management schemes can be used to reduce the amount of traffic in city centres. Paris has experimented with a scheme that allows cars with an even number plate to enter the city on one day and those with odd number plates on the next. Leeds city council operates a policy to encourage car sharing by the use of high-occupancy vehicle lanes, available for cars carrying two or more passengers, hence encouraging people to share cars to enable them to get to work quicker.


Motor vehicles generate more air pollution than any other single human activity. Road transport affects local air quality, influences the global climate and creates economic inefficiency through daily road congestion. In the UK, it has been recognised that the continued mismanagement of an unsustainable transport system cannot continue in the future. Sustainable transport policies will involve more than traffic reduction. New technology is required to increase vehicle efficiency and reduce air pollution from the traffic that remains. Investment in other modes of transport, including public transport, cycling and walking will be needed to encourage individuals out of their cars.