Will low emission zones solve the problem of traffic pollution and congestion?
Clean air campaigner Tim Brown analyses their potential to make a difference

Later this year local authorities will be completing their review and assessment of air quality, and many will be declaring Air Quality Management Areas under the 1995 Environment Act. The act requires authorities to produce action plans to improve air quality, but their options for tackling traffic pollution are limited. Some, like congestion charging and workplace parking taxation, are politically controversial. What can a local authority do to clean up pollution hotspots? Encouraging cleaner vehicles is an obvious alternative. Many authorities are now considering the idea of establishing low emission zones (LEZs), which seek to reduce emissions from road vehicles by encouraging the use of cleaner technologies, or by reducing the number of vehicles overall.

Last year, the National Society for Clean Air and Environmental Protection Cleaner Transport Forum put together a research partnership, including interests from the oil and motor industries, retailers, freight distribution, local authorities, public transport, research consultancies, environmental groups and government departments, to investigate the potential for LEZs to contribute to improving air quality. The forum has now published a report on the framework for LEZs, and a toolkit to help local authorities estimate the potential impact on air quality of various LEZ scenarios*.

What is a LEZ?
The objective of a LEZ is to reduce vehicle emissions, in a given area, in order to improve local air quality. So LEZs could be tightly defined - for instance, only allowing vehicles meeting certain emissions standards into a city centre - or more loosely, through licensing public service vehicles, agreements with fleet operators and encouraging the use of cleaner vehicles in a wider area.

LEZs would seek to exclude more polluting types of vehicle. The simplest way to categorise vehicles is through the current banding of EU emission standards. Selected categories of vehicle could then be restricted or prioritised through a range of measures. Action to improve traffic flow and reduce vehicle numbers overall would also contribute to reducing emissions. Air pollution is only one of the unpleasant features of road traffic. LEZs could also create less noisy, more relaxed, safer town centres.

How will LEZs be created?
Under the Environment Act, traffic regulation orders (TROs) allow local authorities to exclude certain types of vehicles from specific areas in the interests of pollution control. Authorities could also consider voluntary agreements or licensing arrangements with fleet operators, for instance, encouraging bus quality partnerships or taxi licensing which specify emission standards. There are broadly three options for introducing LEZs, with increasing cost and enforcement implications:

• Create an area where access is restricted to certain classes of vehicles (for example, buses, delivery vehicles, taxis) at certain times.
• Introduce permit systems which only allow vehicles which meet certain emission standards to enter - and with a visible permit or identification to show which standards a vehicle meets.
• Use electronic systems which rely on electronic tags or number plate recognition to identify permitted vehicles.

How would LEZs be enforced?
If vehicles are going to be excluded on the basis of emissions standards, a basic requirement - and one which the Government is still considering - is the need for visual identification of qualifying vehicles, so that a certificate, number plate or licence disc would confirm the emission standard of a particular vehicle. Alternatively, voluntary agreements with particular sectors of the fleet could be used to ensure that, for instance, only vehicles meeting certain emission standards were operated in designated areas. Buses, taxis, or local authority contractors would be an obvious target here.

Probably the most sensitive question for enforcement is whether private cars should be excluded from LEZs, particularly in inner city areas where a large proportion of residents might own older (and more polluting) pre-catalyst cars and diesels. Given that air quality objectives do not have to be achieved until 2005, declaration of a LEZ could include a two to three year "upgrade" period before older vehicles were excluded. The Government is also looking at the idea of a scrappage scheme - paying owners to scrap older vehicles - or subsidised catalyst retrofit schemes, which have proved successful in Germany. Both options are potentially costly, but might prove cost-effective if targeted at areas of poor air quality - in other words, linked to LEZs and air quality management areas. Local authorities could therefore find themselves opting to administer such schemes as part of their local action plans.

On the ground, LEZ enforcement could be a job for the police, although environmental enforcement is not currently considered to be a core task for police forces. More likely, the work would fall to traffic wardens or local authority officers, as long as these were recognisable, and suitably trained and accredited. New legislation may be needed to give local authorities powers in this area. This would include decriminalisation of some road traffic offences, to allow local authority enforcement and cost recovery. The current Transport Bill offers the opportunity to bring in this legislation.

Some local authorities are already introducing low emission zones. Nottingham City Council is introducing a central zone only accessible to buses, taxis, cycles and orange badge holders during core times. A second phase will require buses to meet emission restrictions. Monitoring and introduction of electronic controls will follow. The London Borough of Camden has declared a "Clear Zone" region in the south of the borough, and is consulting with local residents and traders on implementation. Oxford City Council is exploring the idea of developing a local consensus-building process for a possible LEZ in the city centre.

Westminster City Council has undertaken a research project on the practicalities of introducing LEZs, concluding that, for London at least, LEZs would have to be established over a wide area to be effective. It is now considering the use of traffic regulation orders and permit schemes for some sectors of the fleet, and planning co-operation with neighbouring boroughs. Consultants W S Atkins have also completed a research contract for DETR on the economic evaluation of transport measures to meet air quality objectives. This found that measures such as LEZs would be more effective than some other traffic management options. Meanwhile, many authorities are joining the ALTER-Europe programme, which now has 40 towns and cities across the UK signed up to a declaration requiring them to develop cleaner fleets and promote LEZs.

Of course the key question for air quality managers is - will a LEZ have an appreciable impact on improving air quality? Local authorities undertaking Stage 3 Review and Assessment will already be familiar with predicting future air quality using traffic data and dispersion models. The LEZ toolkit available from the NSCA Cleaner Transport Forum includes access to computer software which should allow authorities to calculate the air quality impact of various LEZ options. The forum is now embarking on a second phase of research and is keen to talk direct to local authorities who would like to evaluate LEZs in more detail. It will advise on national criteria, monitor progress on LEZs and cleaner fuels, and share information and experience with LEZs as they progress.

*Low Emission Zones: Reducing the Environmental Impact of Vehicles in Urban Areas is available from NSCA, 136 North St, Brighton BN1 1RG. One copy is free to every local authority, additional copies price £25 inc p+p. The Local Authority LEZ Toolkit is also free to every LA, with additional copies £10; a summary is available on the NSCA website: www.greenchannel.com/nsca. Local authorities wishing to explore LEZ options in more detail can contact Tim Brown at NSCA: tbrown@nsca.org.uk.

Tim Brown is deputy secretary (policy and development) at the National Society for Clean Air and Environmental Protection