|
|
| In 1997, The Scottish Office Agriculture, Environment and Fisheries Department commissioned Environment Assessment Group Limited to evaluate and assess the spatial coverage of existing air quality monitoring networks within Scotland; to identify the need for further air quality monitoring sites in order to fulfil the UK's obligations under EC Directives and Regulations (existing and proposed); and, to assist with the implementation of the National Air Quality Strategy. |
|
|
| Main Findings |
|
- Existing air quality in Scotland is generally in compliance with relevant air quality limit and guide values. However; potential exceedences of nitrogen dioxide may occur close to roads with heavy traffic flows, in particular within urban areas; ambient concentrations of PM10 are close to or exceed the proposed EC standards and UK Air Quality Objectives within the main urban centres; and, exceedences of the EC ozone protection level for vegetation is currently widespread, particularly within rural areas.
- There is a need for more air quality monitoring coverage throughout Scotland.
- No deficiencies were identified within the lead and carbon monoxide monitoring networks.
- An additional benzene and 1,3-butadiene monitoring site within the Glasgow conurbation will be necessary under the requirements of the proposed EC Air Framework Directive.
- Additional monitoring of nitrogen dioxide and sulphur dioxide is likely to be necessary in both industrial and rural areas of Scotland.
- A need for additional monitoring of ozone has been identified, in particular in remote rural areas.
- Limited PM10 monitoring is currently taking place, further monitoring in urban and industrial areas and areas close to heavily trafficked roads is likely to be necessary.
|
|
|
| Introduction |
|
| The objectives of the project were three-fold. Firstly, to assess the adequacy of the UK National Air Quality Monitoring requirements with respect to the relevant EC Directives and Regulations (existing and the proposed) and to identify what additional monitoring may be required in Scotland in order to fulfil the UK's obligations. |
|
| Secondly, to evaluate the spatial coverage of the existing monitoring networks in Scotland, in particular, their value in generating information for use by Local Authorities for air quality assessment purposes. |
|
| Thirdly, the results of the project will assist The Scottish Office in the implementation of the UK National Air Quality Strategy, in particular when awarding specific consents to Local Authorities to incur capital expenditure on monitoring equipment. |
|
|
| Methodology |
|
| The project focused on the eight key air pollutants: benzene; 1,3-butadiene; carbon monoxide; lead; nitrogen dioxide; ozone; fine particles (PM10); and sulphur dioxide. The initial stages of the project involved the collection and collation of a substantial quantity of raw data, comprising information on industrial processes in Scotland with significant emissions to air, roads with high volume traffic flows (<250,000 vehicles per day), UK network air quality monitoring sites, and local authority air quality monitoring sites. |
|
| Existing air quality in Scotland was reviewed using the results of the UK Air Monitoring Network. The results were compared with the UK Air Quality Objectives (AQOs) and the EC air quality limit values to determine where existing air quality was close to or exceeded the established legislative limit, guide or threshold values. The industrial and road emission sources and the review of existing air quality were used to identify potential pollution hotspots for each of the major pollution species. |
|
| The final part of the study assessed the current monitoring practices in Scotland, both as part of the National monitoring networks and that carried out by individual local authorities. Potential deficiencies in the current level of monitoring with respect to the requirements of the relevant forthcoming EC Directives and UK legislative requirements were identified. |
|
|
|
|
| Findings |
|
| Air Quality in Scotland |
| Comparison of the monitoring results from the UK Air Monitoring network for benzene, 1,3-butadiene, carbon dioxide and lead with the relevant UK and EC air quality limit and guide levels suggests that ambient concentrations are within the recommended limits throughout Scotland. |
|
| Current nitrogen dioxide monitoring results demonstrate that exceedence of the current EC guide, proposed EC limit value and UK AQOs may occur at kerbside locations adjacent to roads with heavy traffic flows. Exceedence of the UK annual mean AQO may be more widespread, occurring in many urban areas. |
|
| Highest levels of ozone occur in rural areas. Current ozone concentrations are expected to be within the UK AQO, but exceedences of the current EC Directive protection level for vegetation is widespread (particularly in rural areas). In addition, some exceedence of the EC Directive threshold population information value and the EC Directive population warning level may arise. |
|
| The monitoring results demonstrate that ambient concentrations of PM10 are close to or exceed the proposed EC limit values and UK AQO. The highest level of exceedences are to be expected in urban areas close to heavily trafficked roads. |
|
| Sulphur dioxide concentrations are within the current and proposed EC limits, but exceedence of the UK AQO may be experienced where high levels of emissions coincide with periods of poor dispersion. |
|
|
| Efficacy of Current Monitoring |
|
| For each of the pollutants included in this review, the study highlighted the disparity in monitoring between local authority areas This disparity is partly explained by differences in the number of emissions sources. But there is a need for more consistent coverage. This is particularly important when considering pollutants of regional/national concern such as ozone and to a lesser extent their precursors. |
|
|
| Benzene and 1,3-butadiene |
| Potential hotspots may arise in areas near to major industrial sources, where plume grounding or high concentrations of fugitive emissions may occur, in particular in combination with adjacent busy roads. No real cluster of industrial emission sources exists, although several are present in Grangemouth. |
|
| The report finds that sufficient air quality monitoring locations have been established to monitor benzene and 1,3--butadiene concentrations from traffic sources. However, compliance with future EC legislation may require an additional monitoring location within the Glasgow conurbation, and an additional site may be required around the Grangemouth area. |
|
|
| Carbon Monoxide |
| The major concentrations of carbon monoxide emission sources occur in the urban areas of Glasgow, Edinburgh, Aberdeen and Dundee. In these locations there is a concentration of roads with high volumes of traffic close to the city centres and in some places may coincide with significant industrial sources. The existing coverage of CO monitoring sites is relatively comprehensive, although an additional monitoring location could be considered within Dundee. |
|
|
| Lead |
| No deficiencies in the current lead monitoring network have been identified. |
|
|
| Nitrogen Dioxide |
| The major concentrations of emission sources are the urban areas of Glasgow, Edinburgh, Aberdeen and Dundee, where emissions from busy roads are likely to combine with those from industrial processes. In addition, nitrogen dioxide concentrations at Grangemouth are likely to be elevated, due to the significant number of industrial processes and the major traffic flows associated with the M9. |
|
| Under the National Network there is no monitoring of nitrogen dioxide concentrations in any industrial or rural location in Scotland. The forthcoming EC Directive will require monitoring at these locations. |
|
| The UK National Nitrogen Dioxide Diffusion Tube Survey results are not suitable for demonstrating compliance with the majority of the EC and UK air quality standards. However, they will be of use to local authorities in carrying out local air quality reviews. |
|
|
| Ozone |
| Typically, the highest concentrations of ozone are found in rural areas, at some considerable distance from the potential pollutant sources. Areas of high concentration are very dependent on the prevailing weather conditions. The three existing rural monitoring locations within Scotland are not likely to be sufficient to provide a full understanding of the causes and patterns of ozone formation or the extent of the areas which may experience exceedences. In order to aid understanding of the transboundary nature of ozone, additional monitoring sites could be established on the south-west and central east coast of Scotland. |
|
|
| PM10 |
| The main concentration of emission sources occurs in similar locations as those for nitrogen dioxide. Given the significance of industrial sources to PM10 emissions, the highest concentrations would be expected to occur in industrial areas such as Grangemouth, where roads carrying heavy traffic flows occur in conjunction with industrial sources. Elevated PM10 levels are also likely in the major urban areas, where traffic sources predominate. |
|
| The existing monitoring network for PM10 concentrations is relatively limited and does not cover fully the potential areas of exceedences. Given that exceedences of the PM10 limits are predicted throughout the UK, additional PM10 monitoring locations are likely to be necessary. |
|
|
| Sulphur Dioxide |
| The majority of sulphur dioxide emission sources are in Edinburgh, Grangemouth and Glasgow. There is also a significant number of isolated industrial sources in a narrow band along the east and north-east coast. |
|
| Currently there are only two national automatic monitoring sites monitoring sulphur dioxide within Scotland, and no monitoring sites at any industrial or rural location. The proposed Daughter Directive on Air Quality: SO2, NOX, Particulates and Lead (resulting from the EC Ambient Air Quality Assessment and Management Directive) will require monitoring at these locations. |
|
| In areas identified as potential exceedences, it will be difficult to demonstrate total compliance with the AQO without employing large numbers of automatic monitoring stations. It is in these situations that the benefits of dispersion modelling may be of greatest significance. |
|
|
| Conclusions and Recommendations |
|
| One of the findings of the project has been that monitoring varies greatly from authority to authority. Even taking into account the distribution of sources, a more even coverage of monitoring sites is needed. This is particularly important when considering pollutants of regional/national concern such as ozone and to a lesser extent nitrogen dioxide and volatile organic compounds, both ozone precursors. When considering air quality management and, in particular, air quality monitoring, local authorities should be encouraged to consult with neighbouring authorities and, where relevant, develop a joint approach. |
|
| The research demonstrated that additional air quality monitoring sites are likely to be required for the pollutants: benzene; 1,3-butadiene; nitrogen dioxide; ozone; PM10; and sulphur dioxide. Further monitoring sites will be necessary in order to enable the UK to comply fully with EC Directives and to assist local authorities in carrying out air quality assessments of their administrative areas. |
|
|
'An Assessment of Air Quality Monitoring in Scotland', the research report summarised in this Research Findings, may be purchased priced £10.00. Cheques should be made payable to The Stationery Office and addressed to: - The Stationery Office Bookshop, 71 Lothian Road, Edinburgh EH3 9AZ
- Telephone: 0131-228 4181, or Fax: 0131-622 7017
- This Research Findings may be photocopied, or further copies may be obtained from:
- The Scottish Office Central Research Unit, 2J, Victoria Quay, Edinburgh EH6 6QQ
- Telephone: 0131-244 7560
or from the publications sections of The Scottish Office Website: www.scotland.gov.uk |