Air pollution: What is the problem? How can the planning regime help?

By October 30, 2017 No Comments

In this article, Stephen Moorcroft looks at the air quality problems that are currently faced by many UK cities, and asks what benefits can be delivered through the planning regime.

Air quality issues have been high on the agenda over the past few years, and barely a week goes by without a story appearing in the media.  The air quality problems we face are not new, but a series of events have driven the public interest.

Top of the list has been the controversy over the so-called “VW emissions scandal”, in which VW has been found to be fitting “defeat devices” to its cars so as to meet the pollutant emissions standards set by the European Union.  This is not though confined to VW, with many manufacturers finding other ways to pass the official test.  The implications of this are that when driven on the road during “real world” driving conditions, emissions can be many times higher than stipulated by the regulations.  Added to this, we have seen Defra successfully challenged in both the Supreme and High Courts, and ordered to prepare a new national plan that will deliver compliance with the EU limit values “in as short a time as possible”.

On 9 October 2017, four Select Committees[1] re-launched a joint inquiry which will scrutinise the Government plans to improve air quality, and will examine whether the measures are likely to be effective, and whether there is sufficient cross-government collaboration in place to set in place the needed fiscal and policy incentives.

What is the scale of the problem?

Exposure to air pollution is linked to around 40,000 early deaths in the UK each year, and it has been estimated that removing exposure to fine particulate matter would have a bigger impact on life expectancy in England and Wales than eliminating passive smoking or road accidents (1).   Air pollution is also linked to illness, in some instances requiring admission to hospital for strokes, heart attack, lung conditions, or a range of other diseases, all of which places an additional burden on the health system.   Overall, the estimated cost to society is more than £20 billion each year.

At a local level, local authorities across the UK have declared over 600 Air Quality Management Areas – locations where the local authority has determined that there are exceedances of the air quality objectives that have been set to protect human health.  Most of these AQMAs are related to exceedances of the annual mean objective for nitrogen dioxide, principally related to emissions from road traffic.  But even where there are no exceedances of an objective, there is widespread exceedance of the much lower World Health Organisation guideline for fine particulate matter in cities – which is still of serious concern to pubic health.  By way of example, GLA has recently published research (2) that shows that the WHO guideline for PM2.5 (fine particles with a diameter of less than 2.5 micrometres) was exceeded across the whole of Greater London in 2013, and that the vast majority of Londoners (7.9 million) live in areas where the guideline is exceeded by 50%, or greater.

How is this linked to planning regime?

The principal pollutants of concern in urban areas are nitrogen dioxide and fine particulate matter.  Road transport is the principal cause of the problem, but other sources also play a role, such as domestic and commercial heating.  Measures to tackle emissions from all these sources play a key role in all plans to improve local air quality, but there is no single measure that is likely to be successful.

The National Planning Policy Framework (NPPF) provides the basis for local authorities to consider air quality in the development control process.  It places a general presumption in favour or sustainable development, stressing the importance of local development plans, and emphasising the role that the planning system should perform to minimise pollution.  One the NPPF twelve core planning principles notes that planning should “contribute to … reducing air pollution.  However, as noted by the Environment Audit Committee in its third report on air quality (3) “the NPPF does not provide any guarantee of avoiding worse pollution as a result of development , but rather a means of considering all aspects of sustainability, balancing or trading- off sometimes conflicting economic, social and environmental objectives”, and “given the urgent need to make real progress in tackling unacceptable pollution there is a need for the NPPF regime to move that balance more towards air quality protection.”

In 2017, Environmental Protection UK (EPUK) and the Institute of Air Quality Management (IAQM) published a joint document entitled Land-Use Planning & Development Control:  Planning for Air Quality (4). This recognises the important role that land-use planning at the strategic level can deliver to improved air quality, and embodies the concept of “Better by Design” that should be incorporated into all new developments.

It is, of course, recognised that spatial planning will rarely be able to deliver immediate solutions to improving air quality.  But good spatial planning can ensure that future problems are prevented or minimised.  By example, good spatial planning can reduce the need to travel by car to places of work, schools, shops and leisure facilities, by ensuring that new residential developments are in locations where such facilities are readily available, or there are sustainable transport options immediately to hand.  In areas of existing poor air quality, careful consideration to building design and layout can assist in minimising exposure to future occupants of the development.  Consideration should also be given to the location of developments (e.g. with Site Allocation Polices) where sensitive members of the population are likely to be present – by example, it is recommended that new school buildings should be located 100 metres or more away from busy roads in areas where pollution concentrations are high[2].

The concept of “Better by Design” is integral to the guidance, and seeks to move away from a system where mitigation measures are only considered to offset significant air quality effects.  These elements seek to both reduce pollutant emissions from new developments, and to also minimise public exposure.  Some examples of good practice that are encouraged for all developments are:

  • ensuring that new developments do not contravene any Air Quality Action Plans published by the Council, or render any of the measures unworkable;
  • careful consideration of building design and layouts to avoid creating areas that inhibit effective dispersion of pollution; specifically, new developments should avoid creating new “street canyons” where road traffic emissions are trapped by tall buildings on either side of the road;
  • designing buildings to minimise public exposure to pollution sources. This may include maximising façade distances from busy roads and/or locating habitable rooms away from these facades;
  • incorporation of one “rapid Charge” point per 10 residential dwellings and/or 1,000m2 of commercial floorspace; where on-site parking is provided for new houses, charging points should be provided for each parking space; and
  • selection of low-emission plant for heating and hot water provision; ultra-low NOx boilers (<40mg/kWh) and Combined Heat and Power plant with a high level of NOx abatement.

Stephen Moorcroft is a Director of Air Quality Consultants Ltd.  He has undertaken air quality assessments to support planning applications for a wide range of developments including commercial and residential schemes, road schemes, airports and industrial installations.  He was the Co-Chair of the Working Group set up by EPUK and IAQM to draft the guidance on Planning and Air Quality.


  • Royal College of Physicians. Every breath we take: the lifelong impact of air pollution.  Report of a working party.  London: RCP, 2016
  • GLA (2017) PM5 Concentrations and Exposure in London.
  • Environment Audit Committee. Action on Air Quality.  Sixth report of session 2014-15.
  • Moorcroft and Barrowcliffe et al (2017). Land-Use Planning and Development Control: Planning for Air Quality. V1.2. Institute of Air Quality Management.  Available to download at

[1] The Environment Audit Committee, the Environment, Food and Rural Affairs Committee, the Heath Committee and the Transport Committee.

[2] The Mayor of London has recently announced that the 50 schools in London are to undergo an “air pollution audit” to identify effective solutions to protect pupils from high levels of air pollution.