NICE issues guidance on policies to reduce vehicle emissions

BMJ 2016; 355 doi: (Published 01 December 2016) Cite this as: BMJ 2016;355:i6453
  1. Ingrid Torjesen
  1. London

Clean air zones and further congestion charging zones are among recommendations to councils in England to reduce air pollution, in draft guidance issued by the National Institute for Health and Care Excellence.1

Mark Baker, director for the centre of clinical practice at NICE, said, “We can take steps now to encourage people to walk or cycle rather than drive, but these efforts will be futile if we do not have an achievable, long term plan to improve air quality. This draft guidance seeks to redesign how we work and live in cities.”

The guidance recommends that councils take air pollution into account in strategic planning across all departments, focusing on reducing the pollution generated by road traffic and the public’s exposure to it.

Road traffic is estimated to contribute more than 64% of air pollution recorded at urban sites. This comes from exhausts and other sources such as the wear of tyres.2 Long term exposure to particulate air pollution is believed to contribute to 25 000 deaths a year,3 making air pollution the largest environmental risk factor linked to deaths.4

Only five cities outside London—Leeds, Derby, Nottingham, Birmingham, and Southampton—have been told by the government to set up clean air zones to discourage the most polluting vehicles, such as old buses, taxis, coaches, and lorries (but not private cars), from entering the zone through charges. The draft guidance encourages other local councils to consider setting up these zones voluntarily and to take other action to reduce emissions, such as specifying emission standards for private hire and other licensed vehicles, encouraging uptake of low and zero emission vehicles, including by the provision of electric charging points, and by encouraging walking and cycling.

Local councils should also consider incorporating a congestion charging zone within the clean air zone, but with monitoring to ensure that pollution is not increased at the outer margin of the zone, said NICE. However, Ralph Bagge, leader of South Buckinghamshire District Council and deputy chair of the NICE guideline committee, emphasised that congestion zones should be implemented only to tackle traffic related congestion, not as a revenue raising exercise.

Councils should also consider reviewing traffic control measures to ensure that they encourage smooth driving and minimise emissions. These include ensuring that any speed humps are designed to minimise sharp decelerations and accelerations and considering 20 mph zones in residential areas where traffic stops and starts repeatedly. Councils should also consider byelaws and other action to support “no vehicle idling” areas, particularly outside schools, hospitals, and care homes, the document says, and the use of variable speed limits on motorways and major roads to reduce speed in certain sections. The guidance also encourages councils to provide their employees with training in fuel efficient driving, which can reduce pollution and costs. Only around 20% of people who drive for their job have received such training.

Air quality issues should be taken into account in planning, the guidance says. Councils should avoid creating street and building configurations that encourage pollution to build up where people spend time, to site new buildings away from busy roads and at locations that minimise the need for people to use motorised transport, and to site living accommodation away from roadside facades.

The guideline committee noted that current research into interventions relating to air pollutants often focused on environmental or road traffic effects rather than effects on health. They called for further research such as studies into the effect of using different modes of transport along routes taken for work or leisure and a proper assessment of the influence of barriers and streetside trees on air pollution.

Solid barriers are often constructed alongside busy roads to reduce noise, but studies indicate that although they reduce air pollution in the immediate lee of the barrier, slightly further away levels may be higher than without the barrier. Meanwhile, the evidence on trees is conflicting, and their effect depends on where they are sited, street design, number and species of trees, time of year, and tree management. For instance, air quality might deteriorate at street level near vehicle sources if ventilation is restricted by a tree canopy but might be better above the canopy.


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