Publication - Advice and guidance

National low emission framework

Published: 14 Jan 2019
Environment and Forestry Directorate
Part of:
Environment and climate change

Methodology for local authorities to undertake air quality assessment through the National Low Emission Framework (NLEF) to inform decisions on transport-related actions.

31 page PDF

787.7 kB

31 page PDF

787.7 kB

National low emission framework
Appendix 2

31 page PDF

787.7 kB

Appendix 2

Screening considerations

2.1 The screening approach requires consideration of the existing AQAP measures and the likely effects on local air quality.

2.2 Early engagement across local authority functions to ensure that all appropriate planned actions or programmes of work are identified and included within the screening assessment is key to assessing the overall potential for achieving compliance within the AQMA in the shortest possible time.

2.3 The table below outlines the type of information that should be collated to support the screening exercise.


Details on the air quality action plan that sets out a framework for projects and other activities, either with regard to the location, nature, size and operating condition of the AQMA or by the allocation of resources through other programmes of work.

The air quality action plan must provide a clear framework of measures that are directly related to improving air quality or demonstrate a clear link to other programmes of work that represent actions that will have a positive impact on the AQMA.

For example: The local Transport Strategy that sets out a series of actions that will reduce the volume of traffic or the emissions from traffic affecting the AQMA.

Evidence on how the measures in the air quality action plan (and associated programmes of work) will deliver significant progress towards achieving the AQ objective within the shortest possible time.

On its own, the air quality action plan may not provide the measures required to achieve significant improvements. The inclusion of measures associated with other programmes of work undertaken in relation to other functions of the local authority will help toward meeting the air quality objective(s). Consideration of how much any additional measure will contribute towards achieving the AQ objectives is a key criteria in demonstrating the likely overall air quality outcomes of the action plan.

For example: City/town plans that will change the street layout in and around the AQMA, which will promote improvements in air quality and reduce potential exposure of the local receptors.

Information on wider policies/strategies and/or planned actions across the local authority that will promote the integration of environmental considerations, in particular air quality improvements.

The early identification of any plans, strategies or planned actions or programmes of work that have the potential to either reduce or restrict improvements to air quality, regardless of potential positive benefits to the community. The aim of early identification is to allow for potential mitigation measures to be established as an integral part of the policy, strategy and/or planned action and to identify the potential negative effects on delivering improvements in air quality.

For example: Planned transport infrastructure changes that aim to improve traffic flow in a specific location but may restrict future improvements in air quality associated with, or close to, existing or potential AQMAs.

2.3 In identifying plans or programmes of work across local authority functions, it is important to consider the characteristics of the effects and the area likely to be affected. This will assist in determining the potential impact on achieving compliance within the existing AQMA and help to manage the risk of future AQMAs requiring to be declared.

Assess or quantify

The probability, duration, frequency and reversibility of the effects

The more widespread and long lasting the effects identified within the action plan or programme of work, the more likely it is that there will be positive improvement in air quality within the AQMA. If the effects are likely to be short-term, not repeated and easily reversible, it is less likely to be deliver a significant improvement for the AQMA. Where the benefits to air quality are not likely to be long lasting, a NLEF stage two assessment could be required as the plan may not deliver the improvements necessary to achieve compliance with the air quality objective(s).

The cumulative nature of the effects

There are likely to be cumulative effects from the action plan and programmes of work and these can be considered terms of synergistic effects, additive impacts and secondary effects. Cumulative effects can arise from the combination of the actions set out within the air quality action plan and/or programmes of work delivered across other functions and can be positive or negative e.g. the benefit of adopting actions set out in a local active travel strategy could be enhanced by proposed changes to traffic management in the same area. Conversely, the air quality benefits of the active travel actions could be negated by developments proposed in the vicinity of a local transport corridor that will increase traffic volumes and congestion levels.

Transboundary nature of the effects

The transboundary nature of the effects comes from actions by one local authority impacting upon another local authority's AQMA. This is also relevant to multiple AQMAs within a single local authority.

The magnitude and spatial extent of the effects (in terms of geographical area, population or reduction in pollution likely to be affected)

This is an important measure for distinguishing between strategic and project-scale actions in terms of air quality improvements. High-level plans and strategies generally cover a large geographical area with the level of specific improvement measures included being generally low. For AQMA, direct actions or specific programmes of work will generally results in a greater level of potential improvements through delivery of measures directed towards improving air quality. It is important to distinguish between differences in strategic and project scale measures and to quantify potential improvements as accurately as possible to ensure that compliance is achievable in as short a time as possible. The contributions made by the range of plans, measures and actions set out by the local authority should be considered.


Email: Andrew Taylor