National low emission framework

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

Appendix 3

Acronyms, terms, and definitions



Air Quality Management Area (AQMA)

Local authorities review and assess air quality in their area on an ongoing basis, measuring air pollution and predicting how it will change over time. The aim is to make sure that the national air quality objectives will be achieved by the relevant deadlines. If a local authority finds any places with relevant exposure where the objectives are not likely to be met, it must declare an Air Quality Management Area there.

Air Quality Objective (AQO)

A set of air quality standards and objectives has been developed for several pollutants of concern for human health. Each objective has a date by when it must be achieved. The objectives adopted in Scotland for the purpose of Local Air Quality Management are set out in the Air Quality (Scotland) Regulations 2000, the Air Quality (Scotland) Amendment Regulations 2002 and the Air Quality (Scotland) Amendment Regulations 2016.

Air Quality Action Plan (AQAP)

Where local authorities have declared an Air Quality Management Area (AQMA), they have a duty to produce an Air Quality Action Plan (AQAP). The AQAP includes a series of measures that the authority intends to introduce in pursuit of the Air Quality Objectives (AQO).

Annual Progress Report (APR)

The Annual Progress Report (APR) provides an update on the monitoring conducted by the local authority (and where appropriate), the actions set out within the AQAP associated with the AQMAs.

European Emission Standards

Define the acceptable limits for exhaust emissions of new vehicles sold in EU and EEA member states. The emission standards are defined in a series of European Union directives staging the progressive introduction of increasingly stringent standards.

Geographic Information Systems(GIS)

GIS visualise, question, analyse, and interpret data spatially to understand relationships, patterns, and trends.

Heavy Goods Vehicle (HGV)

Widely used to describe trucks with a gross combination mass of over 3.5 tonnes.

Light Goods Vehicle (LGV)

Widely used to describe commercial carrier vehicles with a gross vehicle weight of not more than 3.5 tonnes.

Low Emission Zone (LEZ)

A LEZ is a geographically defined area where the most polluting classifications of vehicles are restricted, deterred or discouraged from access and use. The aim is to reduce the number of polluting vehicles being used in a particular area or accelerate the improvement in fleet quality that would otherwise have occurred. This is achieved by setting particular exhaust emission standards as conditions of entry, with the aim of improving the air quality in that area.

National Modelling Framework (NMF)

The NMF provides evidence based approach to deliver the air quality modelling requirements set out in CAFS. The model consists of the regional NMF model to provide air quality information to support decision making on placemaking and transport planning at a regional level. The local NMF model will focus on gathering, analysing and presenting evidence in a consistent manner to support the NLEF appraisal process.


NOx is a generic term for the nitrogen oxides that are most relevant for air pollution, namely nitric oxide (NO) and nitrogen dioxide (NO2). NOx gases are usually produced from the reaction among nitrogen and oxygen during combustion of fuels, such as hydrocarbons, in air; especially at high temperatures, such as occur in car engines


Particulate matter (PM10) consists of very small liquid and solid particles present in the air. Of greatest concern to public health are the particles small enough to be inhaled into the deepest parts of the lung. These particles are less than 10 microns in diameter - about 1/7th the thickness of a human hair - and are known as PM10.


PM2.5, also called "fine particulates" refers to atmospheric particulate matter (PM) that have a diameter of less than 2.5 microns in diameter, which is about 3% the diameter of a human hair. Commonly referred to as PM2.5. Fine particles can have more serious health concerns since smaller particles can travel more deeply into lungs and cause more harmful effects.


Refers to the addition of new technology or features to older systems. Engine retrofitting involves improving efficiency, increasing output, or reducing emissions although retrofit to the exhaust system is more common.

Road Access Charging

Direct charges levied for the use of roads, including road tolls, distance or time based fees, congestion charges and charges designed to discourage use of certain classes of vehicle, fuel sources or more polluting vehicles.

Vehicle Access Regulation Schemes (VARS)

VARS regulate the types of vehicles which can enter a designated area, usually to improve issues such as congestion or air quality or to increase safety for pedestrians and cyclists or enable priority for public transport.


Email: Andrew Taylor

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