Environmental Standards Scotland air quality investigation - Scottish Government improvement plan

Other recommendations

ESS included in its report a further two recommendations which are not intended to be a formal part of the improvement plan, but which are included here for completeness.

Recommendation 5 - That the Scottish Government ensures that its ongoing review of data provision scrutinises the protocols for the siting of monitoring sites, with a view to establishing whether they provide a sufficiently comprehensive picture of the state of air quality, particularly in and around our major cities. Specific focus should be placed on areas where vulnerable groups are present, such as schools and hospitals.

Scottish Government response – accept recommendation.

An action in CAFS2 is for the Scottish Government, with support from SEPA, to commission a review of air quality data collection and reporting in Scotland. SEPA has compiled a spreadsheet of local authority monitoring locations for LAQM purposes. This includes the c.100 automatic monitoring sites and c. 1100 diffusion tube monitoring locations, and whether the site has recorded exceedances of the air quality objectives within the last five years. SEPA has also reviewed current guidance on monitoring and concluded that this remains fit for purpose.

The Scottish Government, jointly with the other UK administrations, provides comprehensive technical guidance for local authorities to support them in undertaking all aspects of LAQM work. The guidance was most recently updated in August 2022 (TG.22).^[4] Automatic air quality monitors are complex instruments and costly to purchase, operate and maintain. This places a practical limit on the number of locations that can be monitored in this way. It is therefore important that resources are put to the best possible use by ensuring that monitors are optimally located to accurately represent both public exposure and air quality at background locations for comparison.

For this reason, comprehensive screening tools have been developed as part of the technical guidance to help local authorities identify the most appropriate monitoring sites, together with detailed models for estimating pollution levels at locations where automatic monitoring is not possible. In addition, nitrogen dioxide diffusion tubes provide a low cost screening approach which can be easily deployed widely, highlighting areas which may merit more detailed investigation. In recent years there has been significant development of a wide range of cheaper and flexible monitoring technologies covering all the main air pollutants. This sector will continue to expand and improve, with increasing potential to support and enhance the more established monitoring approaches.

Over the years that LAQM has been in place, local authorities have progressively adapted their monitoring strategies in accordance with the specific air quality issues in their areas. Monitoring networks have been extended to cover all potential hotspots, whilst sites are relocated to more relevant areas where necessary or discontinued where compliance has been secured.

Air pollution hotspots will generally be where high levels of traffic coincide with locations where large numbers of people are regularly present. The monitoring network and the supporting methodologies are sufficiently robust to ensure that any areas of concern will be picked up, including those locations where vulnerable groups are present, such as schools and hospitals.

Although these latter locations are in general less likely to experience poor overall air quality, vehicle idling outside schools can be a significant local issue, especially at drop off and pick up times. The Road Traffic (Vehicle Emissions) (Fixed Penalty) (Scotland) Regulations 2003 provide powers for local authorities to issue a fixed penalty notice to drivers of parked idling vehicles who refuse a reasonable request to switch off their engines. Use of the powers is voluntary and it is for individual local authorities to decide whether to make use of them, taking into account their specific air quality issues. The Scottish Government provides guidance and financial support to authorities for this purpose. In 2022/23, 17 local authorities were making use of the powers, with many of these focusing on schools and also conducting education and awareness raising campaigns around the impacts of idling on local air quality.

In addition, SEPA has been closely engaged in educational and citizen science initiatives on air quality with schools and more widely, including the Learn About Air programme,^[5] a package of teaching materials aimed at primary and secondary schools, along with Clean Air Day activities. SEPA were early pioneers in the use of low cost air quality sensors to help facilitate this work, helping schools and local authorities to build the case for restricting vehicles around school gates and promoting active travel.

Recommendation 6 - That the Scottish Government revises CAFS2 to include specific and measurable timescales (consistent with the overarching duty to achieve compliance within the shortest time possible) for when compliance with nitrogen dioxide limit values should be achieved.

Scottish Government response – accept recommendation

Currently, the actions set out in the CAFS2 Delivery Plan have been assigned either short (to be completed by the end of 2022), medium (to be completed by the end of 2024) or long term (to be completed by the end of 2026) status. Further detail has been added to the broad categories to allow a more detailed assessment of progress to be made. All of the non completed actions have been reassessed to assign defined milestones, which in most cases are annual, and a specific date by which the action will be completed. Progress will be reviewed annually and milestone/completion dates adjusted as necessary.

Under the Ambient Air Quality Directive 2008/50/EC, limit values have been set for several air pollutants of particular concern for human health and dates by when these should be achieved. The Directive was transposed by the Air Quality Standards (Scotland) Regulations 2010, which are part of retained EU law following EU exit.

Scotland is fully compliant with all the limit values apart from non compliance for nitrogen dioxide at six locations – three in North Lanarkshire, two in Glasgow and one in Edinburgh. The most recently available assessment projections estimated that all of these bar one of the North Lanarkshire locations would be compliant by the end of 2022, with that location following by 2023. Compliance projections are calculated based on a combination of data from the UK wide air quality monitoring network operated jointly by the four UK Governments, and modelling using the UK Pollution Climate Mapping models.

Differences between EU air quality assessment and Local Air Quality Management

• There are two legislative and policy frameworks for ambient air quality in Scotland (and the rest of the UK) – the Ambient Air Quality Directive 2008/50/EC, which form part of retained EU law following the UK's exit from the European Union, and the Local Air Quality Management (LAQM) system, set out in the Environment Act 1995, at domestic level.
• When comparing air quality under the EU Directive and LAQM, it is important to remember that the two sets of legislation have different assessment requirements. This makes direct comparison difficult.
• Each system has slightly different requirements in terms of air quality assessment. This creates a situation where Scotland is predicted to be largely compliant with Directive requirements by 2023, yet there are still 34 Air AQMAs (at the time of writing) in place under LAQM.
• Under the Air Quality Directive, assessment is undertaken mainly through modelling, cross checked against a small number of monitoring stations in the UK monitoring network. Because of the complexity of the model used for this purpose, only motorways and A roads are modelled. This produces a high level overview of the air quality situation.
• The assessment methodology under the Directive requires assessment anywhere that members of the public have access, not necessarily where there is relevant public exposure to pollutants. There are also clearly defined criteria which must be followed in relation to numbers and locations of monitoring sites.
• LAQM is based more on monitoring data, supplemented by modelling. Under LAQM all roads are assessed, not just motorways and A roads. This approach is designed to identify local hotspots and produces a much more detailed picture of air quality. There is also more flexibility in the siting criteria for LAQM monitoring sites to ensure that all areas of concern can be covered. Unlike the EU Directive, LAQM assessment is only required at locations where members of the public are regularly present.