Cleaner Air for Scotland 2 - Towards a Better Place for Everyone

A new air quality strategy to replace Cleaner Air for Scotland - The Road to a Healthier Future, setting out the Scottish Government's air quality policy framework for the next five years and a series of actions to deliver further air quality improvements.

4. Data

78. There is a comprehensive body of air quality data for Scotland going back many years, which provides an invaluable resource for assessment and policy development.[64] At the same time, it is important that we regularly review our approaches to data collection and utilisation, to ensure that we realise the potential of new technologies, continue to collect data that are relevant, robust and fit for purpose, and link effectively to related datasets that can provide added value in supporting joined up policy delivery.

79. Until relatively recently, the vast majority of real-time measurements of air quality in Scotland and the rest of the UK were made by established reference methods, using monitoring equipment that meets defined international standards for data quality. However, in the last decade there has been rapid growth in the development of low cost sensors for air pollution measurement. These can range from simple single pollutant sensors to relatively sophisticated multi pollutant devices that include communications and meteorological capabilities, differing from reference methods in features such as accuracy, compactness, mobility, lifespan and lower power consumption.

80. Low cost sensors have a number of potential advantages. In particular they allow for a much larger number of measurements to be made, covering a wider geographical area. Some are small enough to be carried on or by individuals, allowing direct estimates of personal exposure to be made. They can also be used to complement or improve upon existing modelling-based approaches to supplement monitoring data. Additionally they can play a useful role in education and awareness raising. At the same time, there are many uncertainties. Sensor technology is evolving rapidly, and accuracy is often an issue, making it difficult to judge the merits of and make recommendations on the use of specific instruments. Therefore data from low cost sensors cannot be used to report directly against compliance with legal air quality objectives. Their use beyond citizen science and awareness raising are to assess spatial and temporal trends to identify air pollution issues that cannot be adequately captured by reference methods. The Air Quality Expert Group (AQEG), which provides independent scientific advice to central government in the UK, has produced a detailed overview of low cost sensor technology and application.[65]

81. Low cost sensors also have a valuable educational role, both in schools and wider citizen science projects. SEPA has been working with schools in several local authorities on the CleanAir@School project, enabling pupils to measure air pollution at their school, with trends being used to build evidence for behaviour change actions. The project had 10 Environmental Protection Agencies (EPAs) across Europe participating, with the final report on the project published in February 2021.[66] Learn About Air[67] is a dedicated teaching resource, linked to Scotland's Curriculum for Excellence, for pupils to learn about air quality, the impact it has on their lives and how they can influence it. It also provides a powerful mechanism to feed this message back into the pupil's home environment, thus reaching the wider population.

Remote sensing

82. At the other end of the data collection scale are remote sensing technologies. Satellite observations can provide extensive spatial and temporal coverage, not just for air pollutant concentrations – with current technology being capable of measuring all the main air pollutants – but for related climatic, meteorological and land use parameters. Whilst the resolution is typically coarser than ground instruments (although this is improving as the technology becomes more advanced) satellite measurements provide full spatial coverage, capable of addressing gaps in areas with little data from other sources. Remote sensing can also be used to support validation of emissions estimates by low cost sensors, besides enabling enhanced forecasting of regional and transboundary air pollution events.

83. The potential for remote sensing to support and enhance standard approaches to air quality monitoring and modelling in a similar way to low cost sensors has not to date been explored in detail in Scotland but will be considered further as part of the implementation of this strategy, taking account of work in this area being progressed by other organisations such as SEPA and the Environment Agency.

Traffic data

84. Good quality data are essential for making key decisions. Historically though, traffic data has rarely been collected for direct application to air quality management and improvement, even though many geographic and time-specific data gathering exercises have been undertaken by central and local government for particular purposes. There is currently no systematic long-term approach to gathering traffic data at a large scale for environmental purposes, and improvements are thus needed in both robustness and utility. This has begun to change in recent years with the introduction of the National Modelling Framework for Scotland (NMF), which provides the basis for a national approach to both local and regional air quality modelling. However the development of detailed local models for Aberdeen, Dundee, Edinburgh and Glasgow to provide the evidence base for Low Emission Zone (LEZ) introduction in these cities[68] was only made possible by undertaking detailed targeted traffic data collections. This contrasts with the well-established approaches for collecting air quality and other environmental data.

85. Traffic interventions to reduce emissions should be based on the best possible transport data that reflects vehicle/people movements and mode choice. The NTS2 calls for an improvement in the quality and availability of information to enable organisations and individuals to (1) plan their journeys in the most cost effective or time efficient way (particularly where an interchange is needed) and (2) inform transport fleet management decisions. We must make it as easy as possible for people to make informed travel choices and encourage more sustainable travel. This will require information to be available that is as close to real time as possible, relevant, reliable and easy to both access and use.

86. Information may relate to air pollution monitoring data derived from a mix of sourcing including reference and low cost sensor networks, real-world vehicle data and various intelligent transport system (ITS) solutions including traffic counts and Automatic Number Plate Recognition cameras. Consideration should also be given to emerging or future third party datasets such as satnav data or mobile phone locational services, which currently help to support congestion detection and support journey planning, along with future connected vehicle datasets.[69]

87. Data sharing between transport agencies and the likes of SEPA, local authorities, the NHS, Public Health Scotland and Police Scotland should also be promoted. Ideally, the information should be stored and managed in a way that allows multiple data sources to be captured and accessed easily whilst complying with General Data Protection Regulation (GDPR) requirements.

88. The Scottish Government implemented a real-world vehicle emission monitoring programme in 2019 using remote sensing technology. Over 300,000 data points were collected on the trunk road network around Edinburgh during October 2019 and February 2020. Emissions monitoring on local and trunk roads improves our understanding of real-world fleet emissions including insight into the performance of emission abatement retrofit technology on fleet vehicles (which the Scottish Government is also funding) and the potential to detect emission defeat-device technology.


We will:

  • Commission a review of air quality data collection and reporting in Scotland. The review will identify any notable gaps in data provision, with recommendations on how to fill these. The review will also provide recommendations on how current air quality data and methodologies can be more effectively integrated with other datasets, particularly those relating to transport, human health, environmental quality and spatial planning.
  • Commission research to explore the potential of utilising satellite data to complement air quality monitoring.
  • Develop an approach for standardised annual collection and storage of traffic data which can be used for multiple purposes, including air quality management.
  • Undertake a review of road transport data capture and associated gaps with relevance to air quality.
  • Collect transport data within Air Quality Management Areas and beyond to support air pollution mitigation planning, following the good practice established by SEPA's National Modelling Framework (NMF).[70]
  • Explore options for transport, air quality and health data sharing between public bodies.
  • Provide guidance to local authorities on how best to always commission traffic data collection in a way that supports local air quality objectives.
  • Develop a central data storage for traffic data to support the development and use of SEPA's regional NMF (and UK AERIUS)
  • Establish a comprehensive network of air quality emissions monitors on local and trunk roads in the early 2020s.



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