Cleaner air for Scotland: the road to a healthier future

A strategy setting out the Scottish Government's proposals for delivering further improvements to air quality.

11. National Low Emission Framework

Legislation and policy

A Scotland where all European and Scottish legal requirements relating to air quality are as a minimum complied with.


11.1 The National Low Emission Framework ( NLEF) is designed to enable local authorities to appraise, justify the business case for, and implement a range of, air quality improvement options related to transport (and associated land use). The NLEF will support and build on the work already being done through the Local Air Quality Management system and, as noted in paragraph 10.14, will support public and private sector contributions to practical sustainable development. It will be supported by the analysis and evidence provided by the National Modelling Framework ( NMF), as described in Section 10.

We will:

  • By April 2016, in further consultation with partner organisations, ensure the NLEF criteria, tests, and processes are developed, agreed, and finalised
  • Design and implement a standard appraisal process for assessing local air quality measures
  • Develop the software tools and associated guidance for the NLEF, including funding options and technical reports, which will underpin the evidence on effectiveness of options

The NLEF process

11.2 The NLEF will be based on the principles of the Scottish Transport Appraisal Guidance [97] , which are well established and understood. This approach gives practitioners confidence that the outputs will be robust, honest, defendable and practical, supporting a business case for implementing any measures. The NLEF process and the associated timeline for delivery are outlined in Table 3. In the meantime, the Scottish Government expects local authorities to continue with ongoing action planning work whilst the process is being developed.

11.3 The NLEF assessment will apply only to local authorities where transport is the main contributor to air quality problems. The NLEF will have a clear link with Air Quality Management Areas ( AQMAs) in Scotland. Therefore, as part of the pre-appraisal process, the Scottish Government and Transport Scotland will assess all authorities with existing or potential AQMAs. Where necessary, local authorities, regional transport partnerships and strategic development planning authorities will work with the Scottish Government and Transport Scotland on the Stage 1 (initial) appraisal and, if necessary, on the Stage 2 (detailed) appraisal. At each stage, national and local government must take account of the outputs of the NLEF process to either progress to the next step or conclude the process. At the end of the Stage 2 appraisal, when positive recommendations are identified, national and local government must work together to develop a robust business case to support these recommendations.

Completed by Stage Key Organisations Outcome Actions required
2015–16 Pre-appraisal Local authorities Regional transport partnerships Scottish Government SEPA Strategic Development Planning Authorities Transport Scotland Defined set of
NLEF options Defined areas for
NLEF assessment Set of NLEF options for each defined area for NLEF assessment NMF tools and
NLEF guidance
evidence report Joint milestone
workshop providing agreement to proceed
to Stage 1
2016–17 Stage 1 (Initial) Appraisal Local authorities Regional transport partnerships SEPA Transport Scotland Impact of NLEF options Costs and benefits of NLEF options Identification of further detail required Business case for
NLEF options to
progress to Stage 2
(Detailed Appraisal)
Initial assessment
report Joint milestone
workshop providing agreement to proceed
to Stage 2
2017–18 Stage 2 (Detailed) Appraisal Local authorities Regional transport partnerships SEPA Transport Scotland Clearly defined impacts Cleary defined costs and benefits of proposed NLEF scheme Business case for NLEF options – within a defined area of enforcement – that should be permitted, to progress to implementation Detailed assessment report Outline business case report Joint milestone workshop providing agreement to proceed to implementation
2018 – 19 Implementation Local authorities Regional transport partnerships Scottish Government SEPA Strategic Development Planning Authorities Transport Scotland Clear definition of scheme benefits and detail Identification of regulatory mechanisms and support required Understanding of infrastructure required Defined funding Application for relevant Transport Regulation Orders Update to licensing agreements Implementation plan Joint supporting measures
Ongoing Monitoring Management and Evaluation As above Defined approach to before and after monitoring, to enable modification and adoption of new solutions following an evaluation-of-effectiveness phase Monitoring plan Joint evaluation Test effectiveness of intervention(s) to ensure objectives are achieved and realised

Table 3. The NLEF process

NLEF Options

11.4 The NLEF will develop a range of transport options for appraisal. The options available to manage the impact of transport or air quality should not be limited to Low Emission Zones ( LEZs) and Clean Air Zones ( CAZs), as these may not be appropriate for

all areas and scenarios. Therefore, the NLEF will also involve considering a wider range of options (see the non-exhaustive list of examples in Table 4) to improve local air quality. These options will be developed further as part of the pre-appraisal process.

Option What it is Key steps
(see Technical Annex for more detail)
1A – Low Emission Zone ( LEZ) Setting minimum emission standards for access to a defined area; either charging vehicles to enter the area or excluding those vehicles that do not meet the standards (such as the example shown in case study 14 from Germany). Evaluate the current range of vehicles operating in the specified area. Define consistent emission standards (or most polluting vehicles), the vehicle types and classes to be excluded and the operation times for the LEZ. Develop a consistent approach to implementation.
1B – Clean Air Zone ( CAZ) Assessing vehicles operating in a defined area. Targeting implementation of measures, other than exclusion, at the most polluting vehicles that enter a space on a regular basis; note the recent guidance published by City
of York Council [98] (as noted in case study 15).
Identify the vehicles to be targeted, with a focus on setting different entry standards
for vehicles based how often a day they enter the CAZ. Engage with operators and others to identify current management and improvement measures. Develop additional measures to deliver further improvements.
2 – Other Access Regulation Schemes Controlling access to a zone based on weight (physical urban access regulation schemes, also known as p-ARS) [99] or at certain times of day (major access regulation schemes, also known as Key-ARS) [100] . Evaluate the range of such measures across Scotland. Develop a consistent approach within the NLEF.
3 – Traffic Management Appraising traffic management in an area and introducing new measures designed to improve air quality. Identify existing measures in the specified area. Define, appraise and, where appropriate, implement a range of additional traffic management measures to improve air quality, including Intelligent Transport Management, road junction upgrades, cycle lanes, cycle corridor lighting prioritisation and public messaging.
4 – Vehicle Licensing Regulations Requiring compliance with specified air quality objectives through conditions attached to vehicle licences for buses and/or taxis. Evaluate the potential effectiveness of this approach for improving air quality. Develop guidance for vehicle licensing in a specified area.

Table 4. Access regulation control options within the NLEF. Note that the options provided in Table 4 are not a full list of options, and other options beyond strict access control may achieve the desired outcome of managing the impacts on air quality; for example, improvements to active travel infrastructure, integrating greenspace, strengthening use of information and communication technologies or such like might achieve the desired outcome to manage air quality impacts. A single form of ‘zone’ could be adopted in Scotland (where the LEZ and CAZ are amalgamated between 1A and 1B) in order to ensure consistency in standards across the country.

Case study 14

Low Emission Zones in Germany – Federal Republic of Germany

Since 2006, over 70 German cities have set up low emission zones ( LEZs), with more than 25 cities excluding vehicles using a vehicle windscreen display sticker (Umweltplakette). The appropriate sticker depends on the emissions code in the vehicle registration, and any further emissions improvement equipment certificate.

In Berlin, Bremen, Frankfurt am Main, Hanover, Leipzig, Osnabrück and Stuttgart vehicles without a green particulate sticker are excluded from the inner city LEZ area. Drivers, who infringe the regulations, risk a 40 euro fine and one penalty point on their licence.

In 2008, all vehicle owners in the state of Bremen were offered the opportunity to apply for and display one of three coloured stickers (red, yellow, and green) based on the emissions category of their vehicle. Control of vehicles in the LEZ was then implemented in a phased manner as follows:

  • Phase 1 (January 2009), vehicles with a red, yellow or green windscreen sticker (at least Euro class 2) could enter the LEZ.
  • Phase 2 (January 2010), only vehicles with a yellow or green sticker (at least emission Euro class 3) could enter the LEZ.
  • Phase 3 (July 2011), only vehicles with a green sticker (at least Euro Class 4) were permitted to enter the LEZ.
  • The phased introduction of the LEZ was supported by a wide range of national implementation measures including a large public awareness campaign, close liaison and collaboration with major freight and bus companies, and a detailed analysis of the fleet.

11.5 None of the measures in Table 4 are new. LEZs and CAZs in particular are well established across Europe. However, the benefits and challenges of implementing these can vary depending on the location and the nature of the air quality issues to be tackled. At present, local authorities in Scotland have powers to establish LEZs and CAZs, and to set their own emissions standards and conditions of use. A number of authorities have considered LEZs, yet none have been taken beyond the feasibility stage.

11.6 The consideration of options, as noted in Table 4, must also demonstrate consideration of the sustainability principle. Multiple benefits in addition to improvements in air quality could be realised, such as:

  • benefits to health and wellbeing (increased uptake of active travel, reduced costs to the healthcare system);
  • societal benefits (through community engagement); and
  • an increased shift to low carbon behaviours.

11.7 The NLEF, supported by a robust NMF, aims to encourage and facilitate a shift from feasibility to implementation by:

  • offering a nationally consistent approach to appraising and implementing measures to improve local air quality; and
  • sharing responsibility across national and local government.

Case study 15

Proposed Clean Air Zone – City of York

In 2014, City of York Council unveiled a package of proposed measures to improve air quality. Their proposals included a Clean Air Zone ( CAZ) plan to regulate bus emissions in the city centre. The CAZ will control the types of buses able to operate in certain areas of the city. However, unlike an LEZ, the entry criterion will not be a blanket Euro emission standard for all buses. Rather, the CAZ will set different entry standards for vehicles based on the frequency per day at which they enter
the Zone.

The CAZ approach has been developed for the following reasons:

  • it requires emission improvement costs that are more proportionate to the frequency at which vehicles travel through AQMAs and the impact they have on local air quality;
  • it is likely to achieve greater overall air quality benefits than a blanket Euro emission standard based LEZ applied to all buses, but will limit the financial impact on smaller operators and infrequent rural services;
  • it will give operators a clear 10-year timetable from which to plan their upgrades and organise their fleets in a way that limits the number of vehicles that have to be exchanged or redirected to other cities; and
  • it allows expansion of similar flexible emission entry controls for other vehicle types in the future if this becomes necessary.


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