Cleaner Air for Scotland strategy: independent review

Conclusions and recommendations from the independent review of the Cleaner Air for Scotland strategy.

6. Agricultural, Industrial and Domestic Emissions


6.1 Much of the emissions and pollution information in CAFS 2015 remains valid. The main pollutants and their sources remain generally the same and are in most cases continuing to show modest reductions. In terms of the emissions dynamics and the drivers, pressures and inputs of pollution, the major changes relate to:

  • The closure of the Large Combustion Plant at Longannet (24 March 2016).
  • Progress with reductions in other regulated emissions.
  • Continued warming temperatures and increasingly unpredictable weather conditions including systems bringing dusts, especially from the Sahara, and pollutants from elsewhere.
  • Increases in ammonia emissions from agricultural sources.
  • Renewables developments reducing the reliance upon and use of dirtier sources of energy for light and heat.
  • Increase in the number of domestic and industrial wood-burners, biomass and medium combustion plant.
  • Changing vehicle engine type (more hybrids and electric vehicles, including expanding e-charging infrastructure, and fewer diesel cars generally as well as fewer dirtier petrol and diesel engine private vehicles, despite increasing vehicle numbers overall).
  • Changes toward cleaner bus fleets.
  • Progressive rail electrification on the busiest routes.
  • The development of cleaner freight vehicles, both heavy and light good vehicles (H and LGVs).[44]

6.2 As part of this review, an Agricultural, Industrial and Domestic Emissions (AIDE) Working Group[45] was established and it produced an extensive report[46], the substantive analysis, observational and recommendations elements of which have been incorporated into this section and Annex 6. There is strong connectivity across the sections of the report in terms of the impacts and sources of the emissions.

Domestic combustion emissions

6.3 The main emissions from the domestic sector are PM (PM10 and PM2.5), NO2 and SO2. A summary of domestic combustion emission sources, pollutants and trends in Scotland can be found in Annex 6a.

6.4 The review has concluded, based on the working group’s assessment that Scotland could and should largely follow the strategy proposed by the DEFRA Clean Air Strategy for these emissions, that a package of interventions is appropriate. A summary of the DEFRA strategy’s recommendations for domestic combustion, and how these relate in the Scottish context can be found in Annex 6b.

Conclusions – Domestic combustion emissions

6.5 The DEFRA Clean Air Strategy provides a good basis on which to build in Scotland. The stricter standards for PM2.5 in Scotland, compared to the UK/England position, mean that Scotland may need to consider further actions. The DEFRA strategy focuses on fuels, stoves and consumer education. It relies on Ecodesign (ED) to achieve reductions in appliance emissions but ED is a base standard and also only applies to new stoves. Effectively addressing the existing stock of open fires and older stoves is an important consideration. Supporting industry initiatives will lead to the installation of appliances that have significantly lower emissions than ED. We have also identified the need to take action in four areas: (1) right appliance burning the (2) right fuel, (3) consumer education and (4) proper installation and maintenance.

6.6 The uncertainty over the level of emissions from domestic burning means that setting definite reduction targets is difficult. Further research into the proportion of emissions attributable to domestic burning, as well as assessment of type and source of emissions, is required. Further monitoring of PM2.5 levels particularly in urban areas is desirable, subject to finding an agreed method of measurement. As up to 50% of locally observed ambient concentrations of PM2.5 can relate to long-range transboundary transport of emissions from outside of Scotland (or the UK) a consistent approach at local, national and international scales is required.

6.7 Actions to tackle air pollution should be co-ordinated with other relevant policies and actions, including those emanating from climate change management responses and those targeted at improving house building and household energy efficiency. Moving away from gas sources, better home insulation, more electric, passive and ground source heating, low input heat-recovery systems and minimising heat loss or inefficient heating and cooking ultimately reduce energy use and/or the need for supplementary domestic heating, fires, stoves etc. These actions will all feed through to reduced air pollution.

Recommendations - Domestic combustion emissions

D1. Implement a package of suitably tailored recommendations on domestic burning emissions in Scotland, including: the implementation of Ecodesign (ED); voluntary codes for stoves; appropriate standards for fuels (including regulation of wood for use in woodburners, house coals and arrangements for own-resource wood burning), and education to inform consumers.

D2. Consider with local government and SEPA how best to address the current permitted development status of flues for woodburning stoves and biomass boilers and incorporate permissions into development control and monitoring.

D3. Commission further work to clarify the level of PM (and other relevant) emissions in Scotland and the percentage attributable to domestic burning. This will require re-evaluating the volume of wood burnt.[47]

Industrial emissions

6.8 Emissions from industrial activities in Scotland have been subject to increasingly strict regulation since the mid-1990s as a result of EU, UK and Scottish legislation. SEPA has been recording the mass emissions from the largest regulated sites since 2002 using its Scottish Pollutant Release Inventory (SPRI)[48] system, which collects data for the main pollutants of concern. Emissions from industry can be variable as controls are typically set based on emission limit values (ELVs) from point sources (rather than mass emissions from the installation as a whole). As a result, emissions can fluctuate due to production needs, but still be in full compliance with permit conditions. A summary of the emission trends from SEPA-regulated sites since 2002 is included in the full working group report[49], with a summary of key points of interest provided in Annex 6c.

6.9 Industrial emissions are subject to strict control under a well-defined legal framework using the principle of Best Available Techniques (BAT). The EU Industrial Emissions Directive[50] (IED) (which covers the most polluting industrial activities) along with domestic provisions which comprise the requirements of the PPC regime in Scotland are wide-ranging, comprehensive and provide for a good level of protection of the environment as a whole. In general terms, this is demonstrated by the annual reduction in emissions observed in the data contained within SPRI. Therefore any sCoPe for requiring further reductions of emissions to air without imposing excessive burden on business or the perception of “gold-plating” of existing legislation must be considered very carefully. Further discussion of flexibilities in IED/PPC that could be used to further reduce levels and impacts on air quality from industrial activities can be found in Annex 6d.

Carbon Capture and Storage (CCS)

6.10 It is unclear at this point whether CCS may be more fully resurrected once more and implemented at scale as part of an interim carbon management strategy or not. Were it to be the case that a major development occurred, it would need to be factored into industrial emissions regulation. This would be of particular interest especially if the technologies incorporated included more input energy, use of amine scrubbers etc. and thereby liability to release further gas and particulate pollution. We understand that Project Acorn may be operational by the mid-2020s. Both the Scottish Energy Strategy and the latest Committee on Climate Change report highlight an important potential role for CCS and it is apparently a major area of interest to the National Infrastructure Commission for Scotland. Given CCS seems to have positive and negative implications for air quality, in greenhouse gas (GHG) and air pollution terms it could be significant. It is important that climate and air pollution interventions do not work against each other.

Possible interventions – Industrial emissions

6.11 There are a few areas which could be investigated for developing future interventions to further reduce emissions to air from industry; however, recognising the comprehensive legal framework which already exists, any environmental benefits must be balanced against costs of regulation (to industry and regulator) and a robust justification provided for the need for inclusion for control. Areas for possible further investigation include:

  • Whether there is environmental benefit in bringing currently unregulated sectors (which have not been prescribed by EU legislation) such as non-waste anaerobic digestion under the remit of existing legal frameworks for emissions to air;
  • Whether amendments to the existing legal framework are necessary to remove omissions, ambiguities, loopholes and gaps (e.g. BAT and stack heights not applying to activities falling within the provision of the Medium Combustion Plant Directive (MCPD), clarifying legal definitions and their intent), appropriateness of capacity thresholds, which could help increase control of emissions;
  • Whether additional reductions in industrial sources of emissions can be achieved where certain pollutants are not showing a downward trend (e.g. NH3 and NMVOCs). SEPA is currently conducting work through its sector planning approach which could help further reduce emissions of these substances from specific sectors (e.g. whisky, crop and dairy production) through “beyond compliance” measures. However, opportunities may be limited, as previously discussed, due to a number of installation/sectors already operating in accordance with BAT and their permit conditions and further emissions reductions being limited by production levels and site-specific factors. Emissions of NH3 from intensive agriculture sector are discussed in the agricultural emissions section of this report;
  • Mobile and non-road machinery emissions which have no abatement and use polluting fuels (e.g. construction equipment, road cutting, surfacing, digging, traffic management machinery and diesel and other generators, etc.) could be considered for regulation, given potential local impacts.

6.12 Finally, there may be merit in quantifying/estimating the types and levels of air pollutants being released by other currently unregulated sectors to identify where opportunities exist to bring them into regulation. In many cases currently unregulated sectors already operate under well-defined, regulator-approved, environmental guidance (such as NetRegs); however, to avoid the need to bring these sectors into formal regulation, consideration could be given to making the current guidance into formal Codes of Practice (CoPs) and enforceable through General Binding Rules (GBRs).

Conclusions – Industrial emissions

6.13 Industrial emissions in Scotland have been subject to increasingly strict regulation since the mid-1990s as a result of EU and domestic legislation. As a result, releases of the most significant pollutants have showed generally downward trends, although some are now increasing meaning further, concerted, action is required.

6.14 Due to the prescriptive nature of the legal regimes controlling industrial emissions, further reductions may be difficult unless measures which go beyond compliance are implemented. SEPA is currently taking this approach with 15 sectors which cover sources of industrial and commercial emissions. With the current uncertainty over the UK exit from the EU it is difficult to assess the future implications for emissions control; however, implementing EU requirements into domestic legislation has demonstrated that controls placed on industry are proportionate and effective in reducing emissions. This being the case, provided we maintain the current EU requirements on a domestic basis (as a minimum) further emissions reductions should be achievable, providing further environmental benefit.

Recommendations – Industrial emissions

I1. Build on SEPA’s sector plan approach to further reduce emissions where “beyond compliance” measures may be required to achieve these (e.g. NMVOCs and NH3) and seek to include any further air pollution sources or hazards identified.

I2. Consider inclusion in regulation of mobile and non-road plant emissions (road cutting, surfacing, digging, traffic management machinery and diesel and other generators, etc.), especially given potential local impacts.

Agricultural emissions

6.15 Agricultural emissions related to air quality are dominated by NH3. NH3 is a reactive nitrogen compound which is released when slurries, manures and nitrogen fertilisers come into contact with the air. It produces odours and is mobile, combining with acids and particulates, resulting in identifiable polluting and nuisance effects. NH3, and therefore fertiliser value, can be lost whenever slurry or manure is exposed in this way and so practices that reduce exposure in housing, storage or during application to crops can cut losses and result in the more efficient use of nitrogen in organic and inorganic fertilisers, thus saving businesses money in the long-run. Recovering as much nitrogen as possible will maximise returns from farm inputs and good practice in managing soil, manure, fertiliser and feed will help reduce ammonia emissions (and nitrogen losses).

6.16 Despite long-standing guidance availability, in Scotland, until recently, there has been little coverage of NH3 in the agricultural press. Consequently there is generally poor awareness of this issue across the sector. Therefore, engagement with the sector is needed focusing on farmers and the changes they can make which will deliver both environmental and economic benefits. For the later, the concept of retaining the nutrient value of manures and fertilisers will be important.

6.17 In addition to the financial savings that farmers achieve through reduced NH3 emissions, there are also public good benefits and minimised operational risk. Work is required to analyse the costs and benefits of mitigation options. This is important because in some instances changing farm management to reduce emissions – covering tanks and lagoons etc. - will require significant up-front investment, which may be difficult for many farmers in the short term. As such, a more detailed analysis of the costs and benefits of possible mitigations set within the Scottish context is required.

Background and emissions

6.18 Scotland emitted 34 kt of NH3 in 2016, which was 12% of UK emissions. NH3 emissions have decreased by 12% in Scotland since 1990; a much smaller reduction than for other pollutants. The agriculture sector dominated the ammonia emissions inventory, producing around 90% of Scotland’s ammonia emissions in 2016[51][52].

6.19 Since 1990, decreasing animal numbers and a decline in fertiliser use reduced emissions. An increase in the use of urea-based fertilisers recently has however led to higher emissions. Further detail on the policy context for agriculture emissions, trends and impacts of NH3 and other air quality emissions from agriculture in Scotland can be found in Annexes 6e and 6f, and in the Working Group’s full report[53].

Ammonia abatement options[53]

6.20 The Gothenburg Protocol requires a national advisory code of good agricultural practice to control NH3 emissions. Guidance was provided in the United National Economic Commission for Europe (UNECE) Framework Code for Good Agricultural Practice for Reducing Ammonia Emissions[54], and in Options for Ammonia Mitigation[55] from the Task Force on Reactive Nitrogen. DEFRA published a voluntary code of good agricultural practice for ammonia reduction[56] for England in 2018; equivalents are in development in Wales and Northern Ireland.

6.21 Consideration should be given to a similar code with parallel abatement options for Scotland. Options need to be reviewed in a Scottish context (e.g. climate, soils, agricultural practice), whether for an equivalent voluntary code of practice or formal regulation. Recent work has been done on the health and environment impacts, and on the costs and benefits of NH3 reduction measures[57] [58][59]. These can be taken as a starting point to investigate the costs and benefits of application in Scotland. Recent analyses suggest the potential to increase nitrogen use efficiency by matching livestock producers with excess nitrogen to arable farms with demand[60].

Interventions – Agricultural emissions

6.22 Given that NH3 and the effects on human health and ecosystems/biodiversity of agricultural emissions have not been overtly included within air quality policy to date, and that the issues have not been communicated to the agricultural sector beyond former Scotland’s Environmental and Rural Services (SEARS) initiatives, SEPA/SG Prevention of Environmental Pollution from Agricultural Activity (PEPFAA)[61] advice and guidance, especially connected to ammonia, nitrogen and the water environment as well as farm waste initiatives previously and other periodic cross-compliance initiatives hitherto, the emissions working group concluded that the emphasis of future action should be on education: engaging with and helping prepare the agricultural sector to reduce ammonia emissions. The Steering Group agrees with this but notes that this ought not to be seen or presented as a wholly new subject.

6.23 Through advice already available via Farming for a Better Climate[62] and Farming and Water Scotland[63], there is good awareness on many farms of measures to improve nutrient efficiency on-farm through good soil, fertiliser, manure and slurry management. Improving awareness and implementation of these measures will help reduce ammonia emissions. Again, it would be appropriate to ensure that air pollution management strategies were integrated with necessary climate management actions and indeed other water, flood, habitat and waste management actions underway to ensure unintended consequences do not occur (e.g. pollution swapping).

6.24 The emissions working group suggested that the Scottish Government work with industry to develop a voluntary code of practice. This appears a minimum approach. This code should identify the measures necessary. A voluntary code supported by the industry would set appropriate expectations and help businesses develop an appropriate timed action plan.

6.25 While there are opportunities to deliver both emission reductions and improved business performance and sustainability, mitigation practices may require investment in infrastructure and new equipment. Consequently, the development of a voluntary code may need to be accompanied by an assessment of investment and support requirements. Where action is needed as a priority and subject to the early success of engagement efforts, consideration of environmental and health pressures as well as the benefits involved, a regulatory approach may ultimately be necessary.

Conclusions – Agricultural emissions

6.26 There is a large body of relevant evidence and the review supports much of the approach taken in the DEFRA/UK Clean Air Strategy relating to Agriculture, building on guidance used in Scotland over the last 15 years. Further work to incorporate relevant elements into a tailored Scottish context would be helpful and this should be done urgently given the issues identified with ammonia and NMVOCs for example, as well as the elements relating to climate impact mitigation. There is a good understanding of the practices that can reduce and mitigate emissions and many of these could and should be adopted voluntarily and have long-term positive business benefits if taken up quickly. If uptake is slow and the problems identified continue, more direct regulatory intervention would be necessary.

Recommendations – Agricultural emissions

A1. As a minimum, Scottish Government should urgently work together with SEPA and the agricultural industry to develop a voluntary code of practice (CoP) for Scotland. This should incorporate recent data from the UK agricultural ammonia emissions inventory, use relevant Scottish data, address management practices[64] and seek to engage the agriculture sector to achieve best delivery. The CoP should be subjected to an early review process to assess its effectiveness and compliance. If the review highlights through appropriate monitoring an inadequate impact, direct regulatory intervention should be considered.

A2. SG should undertake work on habitats and emissions to set appropriate targets in the current context of the UK reporting on the NECD. Consider related improvements to the current site condition monitoring of designated conservation sites, to improve on current method, which doesn’t detect air pollution effects and assess current terrestrial ecosystems monitoring to ensure it is fit for purpose.

A3 A specific assessment is needed of visible smokes and their health and amenity impacts. This should include both muirburn and stubble–burning, as evidently significant contributors not previously assessed. A specific assessment of pollution characteristics and downwind impacts into populated areas should be considered, along with appropriate management responses and interventions.


6.27 It is clear from the analysis of agricultural, industrial and domestic sector issues above that a series of actions can be taken to reduce further the emissions from non-transport human activities in general.

6.28 It is also clear from all of the elements addressed above that it is essential to ensure the facts are available. To enable assessment of and reporting on any and all emissions, in addition to more local data systems, there is a marked need to ensure high level compliance[65] monitoring is possible from the timely availability of robust data on all major pollutants of relevance to human health and the environment. Regulatory data require careful management as it may be used for legal purposes but appropriate monitoring is technically available in near-real time. This should be carefully considered for widespread availability. It could also be helpful for refreshed guidance and suitably updated information on appropriate and available equipment, methods and training etc. for data gathering on air pollution, for fixed and mobile facilities and for appropriate chemical species.

6.29 We also note the potential for remote sensing technologies to be deployed, including as part of the learning from the EU LIFE GySTRA programme[66] which “seeks to create a new sustainable mobility policy based on empirical information on road traffic emissions”.[67]

6.30 Finally, General Recommendation 4 (Better Data) above addresses the need set out here for a more integrated and highly populated data gathering and monitoring regime for all emissions.



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