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ROADS (SCOTLAND) ACT 1984; ACQUISITION OF LAND (AUTHORISATION PROCEDURE)(SCOTLAND) ACT 1947
M74 SPECIAL ROAD (FULLARTON ROAD TO WEST OF KINGSTON BRIDGE) ORDERS
REPORT OF PUBLIC LOCAL INQUIRY INTO OBJECTIONS
VOLUME 1 : MAIN REPORT

CHAPTER 6: AIRBORNE EMISSIONS

The Case for the Trunk Road Authority and Supporters

Air quality

6.1 The case for the TRA is based on a computer modelled research study recorded in chapter 15 of the ES and in Technical Annex K1 and Appendix K1, the study following the guidance in the DMRB. In terms of air quality, the environmental impact requires to be assessed against: -

• air quality standards and guidelines;
• air quality in the absence of the motorway, principally in the area of central and south east Glasgow;
• the methods used to evaluate changes in ground level concentrations of pollutants emitted from road traffic;
• an evaluation of the predicted concentration changes against background concentrations and relevant air quality standards and guidelines; and
• a quantification of the changes in carbon dioxide emissions resulting from the M74C.

6.2 With this type of road scheme, air quality changes cannot be identified as entirely negative, or entirely positive. Because the effects will be experienced over an extensive road network, a view of the net exposure to airborne pollutants for the population affected over a wide area is required.

6.3 Air pollutant concentrations change over time for reasons such as control measures or increased human activity. Over the next 10 years, concentrations of a number of road traffic related pollutants are expected to decline substantially. For this reason, it is important to define a reference year against which changes can be assessed. In this case, the year selected is 2010, because by this time the M74C (if permission is granted) will be in operation and 2010 is a key year for air quality legislation.

Air Quality Standards & Guidelines

6.4 Air quality is assessed against standards and guidelines set out in EEC Directives, incorporated into UK law, that are generally based on the need to protect human health.

6.5 The 4 sources of air quality standards and guidelines that are relevant are as follows: -

(1) The Air Quality Regulations (2000) and subsequent amendment for benzene and carbon monoxide in 2002 which incorporate the Government's objectives for air quality in the next 5 years as described in the Air Quality Strategy (2000) and its subsequent Addendum (2003).

(2) The European Commission Daughter Directives for certain revised air quality standards, which provide the basis for some of the air quality objectives set in the latest Air Quality Strategy documents.

(3) Recommendations for air quality standards proposed by DEFRA's Expert Panel on Air Quality Standards (EPAQS).

(4) The World Health Organisation (WHO), which formally published revisions to some of its air quality guidelines in November 1995.

6.6 Any assessment of air quality impacts must take account of existing concentrations of pollutants and the future air quality without the M74C. The description of existing air quality is based largely on data from (1) national networks sponsored by the DEFRA, such as the Automatic Urban and Rural Network (AURN), which has 3 monitoring stations in Glasgow; (2) monitoring carried out by GCC's Environmental Protection Section; and (3) interpolation of monitoring data and emissions data by DEFRA's sub contractor, "netcen" and available on the National Air Quality Archive web site.

6.7 Pollutant concentrations in the atmosphere are constantly fluctuating because emissions to atmosphere vary in their magnitude with time and weather conditions such as variations in wind speed. Factors such as topography and thermal mix are also influential. Examination of any recording of pollutant concentrations made by continuous analysis will show pronounced 'peaks' and 'troughs' of ambient concentrations.

6.8 The research study considered existing levels of nitrogen dioxide, particulate matter, lead, carbon monoxide, hydrocarbons, including polycyclic aromatic hydrocarbons, and sulphur dioxide. Concentrations of NO2 are the most critical of any pollutant in terms of the M74C, with regard to compliance with air quality objectives. In Glasgow, 76% of nitrogen oxide emissions are attributable to road transport. There are 3 monitoring regimes for NO2 levels. The 3 AURN sites in Glasgow indicate NO2 levels exceeding current objectives at 2 of these sites over the 5 year period 1997-2002. National NO2 Survey Data - part of DEFRA's diffusion tube survey - indicates, with 2 minor exceptions, compliance with annual mean objectives. Finally, GCC's own diffusion tube monitoring at a large number of sites across the city indicates compliance with objectives.

6.9 Netcen estimates of background concentrations of NO2 in the Glasgow area are as follows: -

The forecasts for the years 2005 and 2010 are within the relevant standards for those years, while the top end of the forecasts for the 2001 figure slightly exceeds those standards.

6.10 As regards particulate matter, the annual average concentration of PM10 in the vicinity of the M74C corridor (without the new motorway) is 18-20 µg m-3, with highest concentrations found closest to the city centre. The currently applicable air quality objective for annual average concentrations of PM10 is 40µg m-3. Existing concentrations are easily compliant with this objective. In 2010, however, the objective for Scotland will be reduced substantially to 18 µg m-3. Predictions by netcen are that this target will be achieved in all but the centre of Glasgow by 2010. Nationally, emissions of primary particles are expected to reduce in future years, through the continued application of abatement technologies in industry and motor vehicles. With decreasing emissions of SO2 and NOx, secondary particle concentrations should also diminish. Thus, there is a justifiable expectation that future PM10 concentrations will be lower than they are today, although improving this aspect of air quality is more difficult than in the case of NO2.

6.11 As regards carbon monoxide, this is a pollutant almost exclusively associated with vehicle emissions. Consequently concentrations are highest in heavily urban areas with high traffic densities. The annual average concentration of CO in Glasgow is highest in the city centre, at approximately 600 µg m-3, declining to 300µg m-3 at the edge of the city.

6.12 In relation to hydrocarbons, vehicle emissions contain a great many hydrocarbon compounds. Two are of particular importance in the context of the Air Quality Strategy, namely benzene and 1,3 butadiene, both being carcinogens. The air quality objective for 2010 is for annual average concentrations of benzene to be less than 3.25µg m-3. Current concentrations in Glasgow are 1µg m-3 or less and therefore compliance is not a problem for this pollutant.

6.13 Concentrations of 1,3 butadiene are not measured directly in Glasgow at the present time but from knowledge of earlier measurements made by GCC and of similar urban areas, it is likely that annual average concentrations are substantially below the air quality objective value of 2.25µg m-3.

6.14 In regard to lead, measurements at DEFRA's multi element sites in Glasgow and Motherwell indicate levels well within the relevant standards for this pollutant, the impact of which has declined substantially with the shift to unleaded fuel.

6.15 The adoption of an air quality objective for PAH (benzo-a-pyrene) has stimulated more widespread measurement of PAH concentrations than was previously the case. The DEFRA 2001 AQS consultation document provides a summary of measurements of benzo-a-pyrene concentrations around the country, which shows that concentrations are declining. The annual average concentration in Glasgow in 2000 was 0.12 µg m-3.

6.16 Sulphur dioxide is associated with combustion, primarily with coal and oil burning. Whilst it was one of the major pollutants of concern before 1980, concentrations in ambient air have declined to such an extent that it is now not a significant issue in terms of general air quality. In the context of the M74C, SO2 can be ignored as a pollutant for consideration, since background concentrations are low and the scheme has no significant emissions of this pollutant.

6.17 The Environment Act 1995 required local authorities to carry out a formal review and assessment of air quality, according to guidance issued subsequently by DETR and DEFRA. The City of Glasgow has done this, in 3 stages, and reported its findings. The Stage 3 Report, published in 2002, led to the declaration of an Air Quality Management Area ("AQMA") in the city centre, bounded by the M8, the River Clyde, and an eastern boundary defined by Saltmarket Street, High Street, Duke Street, Knox Street and Wishart Street. This small area has relatively high concentrations of NO2 and PM10, and requires action to reduce concentrations in order to comply with air quality objectives. Emissions from vehicles using the M74C would not significantly affect air quality within this AQMA directly, but the scheme would have some positive implications for the AQMA by diverting traffic flows away from this more polluted area. As a consequence, emissions from road traffic within the AQMA will diminish, resulting in improvements in roadside air quality.

6.18 The existing ambient concentrations of the key substances to be emitted from vehicles using the M74C (i.e. NOx, PM10, CO and some hydrocarbons) can be estimated with a reasonable degree of confidence, using the data collected by routine monitoring programmes. In brief, existing air quality in the Glasgow area is consistent with that which might be expected in any large city. Concentrations of all pollutants will meet all air quality objectives set for 2005 (and defined in the Air Quality Regulations) for most urban background locations, but concentrations of NO2 and PM10 in the city centre are expected to be close to values defined as air quality objectives. The M74C is not to be built in the most polluted area of Glasgow, which is the city centre AQMA.

The predicted impact of the M74C

6.19 The evaluation was undertaken using complex modelling techniques described in the ES.

6.20 Because the M74C has implications for traffic flows over a very wide area, affecting roads across central Scotland and beyond, two study areas were identified for the Environmental Impact Assessment - the Wider Study Area and the Detailed Study Area - allowing evaluation at two different spatial scales.

6.21 The wider study area covered the road network across Glasgow and neighbouring towns (Figure K6.2 in the ES), extending from Strathblane in the north west, Denny in the north east, Lesmahagow in the south east and Galston in the south west. Within this area, consideration was given to those roads predicted to experience a change in road traffic flows of 10% or greater. Impacts at this scale were evaluated in terms of the proportion of residential properties at or near the roadside experiencing changes in concentrations of the key pollutants, i.e. NO2 and PM10. Specifically, properties were counted within 200m of roads. Changes to roadside concentrations were calculated using an adapted version of the DMRB spreadsheet method, an approach commonly used to assess the impacts of road schemes, as a 'screening level' tool. Usually, it is used for single road links, but ERM has created a version that is able to use the output of the traffic model for many thousands of links simultaneously. The calculation of air quality changes across this wider study area is a 'coarse' level view of the air quality changes, to allow an appraisal to be made of the net impact of the air quality changes, as it involves the summation of a large number of small positive and negative changes in pollutant concentrations.

6.22 The second study area covered a smaller area, namely, the M74C itself and adjoining roads (Figure K6.3 in the ES). This is broadly speaking bounded on the north and west by the M8, on the east by the M73 and on the south by Cathcart, Cambuslang and Uddingston. Road traffic emissions were used as inputs to a dispersion model capable of quantifying changes in concentrations within this smaller study area, for direct comparison with existing air quality and air quality objectives. Nearest residential receptors were identified along the motorway route, as depicted in Figure 4.4 of the Environmental Statement. The diagram also shows the actual route versus the representation of the model road links. It gives a 'fine' level view of the air quality changes in the vicinity of the new motorway. The dispersion modelling exercise benefited from the availability of climate and meteorological data from the Meteorological Office at Glasgow Airport. The data obtained is considered to be representative of the M74C area. In addition, the ADMS dispersion model used in the analysis has the capability of allowing for the chemistry necessary to take account of the oxidation of nitrogen monoxide to nitrogen dioxide.

6.23 The ES presented the results of the impact assessment at the 2 spatial levels, concentrating on the 2 main pollutants of relevance i.e.NO2 and PM. Over the wider study area, it was able to show the balance of positive and negative impacts in terms of roadside properties affected. This was a semi-quantitative exercise, used to determine the broad impact in aggregate across a large area. For the smaller area, focused on the new road and immediate surroundings, the dispersion modelling produced detailed and quantified predictions of changes in concentrations.

The Wider Study Area

6.24 The EIA has predicted that in future years, the effect of the M74C on road traffic flows will result in air quality improvements at a significant number of near roadside properties, but that some properties will experience slightly higher concentrations. More properties will experience reductions in air pollutant concentrations than the number experiencing increases. These are properties within 200m of the road network. It should be noted that the result is directly dependent on the traffic model output.

6.25 Approximately 3.5 million 'properties' are accounted for in this way This is a greater number than there are actual properties, because of multiple counting in the mapping process, where a property influenced by more than one road appears as more than one entry in the calculation.

6.26 In percentage terms, the analysis shows that for the year 2010, 45% of the properties within 200m of roads considered in the wider study area would experience a reduction in NO2 concentrations, as compared with 25% that would experience an increase, with the remaining 30% experiencing no discernible change. About 56% of properties would experience a reduction in PM10, 43% an increase, and 1% no change. (Table K6.4 p.K49 of ES)

6.27 The evaluation shows that the road links causing increases in NO2 concentrations are mainly associated with the M74C itself and the roads linking to it through the Coatbridge and Paisley areas. In central Glasgow, along the M8 to the north of the city centre and along the A726, the scheme brings air quality benefits.

6.28 In relation to health issues, the assessment indicates that in 2010, as a result of the M74C, there would be a 12% reduction in the number of properties in the wider study area that would be exposed to concentrations of nitrogen dioxide (NO2) high enough to be non-compliant with relevant government air quality objective of 40µg m-3, as compared with the 2010 Do Minimum. There would be a very slight reduction in the number of properties where the annual average PM10 concentration is non-compliant with the air quality objective of 18µg m-3, as compared with the Do Minimum case. (Table K6.5)

6.29 The air quality assessment also shows that the M74C would have beneficial effects on the air quality within the Air Quality Management Area designated by Glasgow City Council for the city centre area. About 58% of the near roadside properties would experience a decrease in annual average NO2 concentrations, whereas 29% would experience an increase.

The Detailed Study Area

6.30 The detailed dispersion modelling for this evaluation was undertaken for 5 separate but contiguous areas along the length of the M74C. The ES displayed the results of these modelling exercises for each of these areas, in the form of contour plots of NO2 concentrations for the 'Do Minimum' and 'Do Something' scenarios in the year 2010.

6.31 The modelling exercise was extremely complex and the ES should be referred to for the detail. The annual average concentration of NO2 recorded in 1997 at the Glasgow City Centre site was 43.5µg m-3. The prediction by netcen is that this value will have fallen to 33µg m-3 in 2010. An initial and cursory inspection of some of the modelling results in the ES for locations next to the new motorway (Figure K4.5 or at pages K1-33-54) suggests that annual average concentrations of NO2 in some places would be in excess of 50µg m-3. Concentrations as high as this would be well above the air quality objective value of 40µg m-3.

6.32 In fact, concentrations are expected to be much lower, because of the anticipated reduction in background concentrations between now and 2010 (as set out in K4.10 of the ES). Only in the area at the junction with the M8 is it predicted that annual average NO2 concentrations would be in excess of 40µg m-3, and this is not primarily because of the new motorway but the influence of the higher traffic concentrations in the city centre and on the M8. These are not locations where the public would experience long term exposure.

6.33 The modelling has provided estimates of the concentrations at 20 locations, selected on the basis that they are the nearest locations to the new road at which members of the public are likely to be present and exposed over periods of time that are consistent with those used in defining the air quality objectives. The smallest practical unit of time in this respect is one hour. These modelling results are summarised in Table C1 of Appendix C. The results were not identified by street names in the ES. The nearest location to the M74C route is at the junction of Eglinton Street and Devon Street, which is entered in the modelling process as a distance of 23m from the road centre. At this point, the annual average NO2 concentration in 2010 is estimated to be 39.3µg m-3. Of this total, the contribution from the M74C traffic would be approximately 3µg m-3. This would be the most affected receptor along the length of the new road. The ES shows (table K4.5) that all other receptors would experience lower concentrations, with the relatively higher concentrations at the western end of the route.

6.34 The new motorway would be expected to contribute to higher NO2 concentrations at locations within 100m, relative to current concentrations or future concentrations in the absence of the motorway. Table 5.1 of the ES (page K38) lists 231 properties within 100m of the motorway, of which 119 are residential, 87 industrial, 15 retail, 5 office, 4 community, and 1 recreation. The nature of the route is such that this would lead to relatively low increased human exposure, given the small number of residences affected. For residents within approximately 500m of the M74C, road traffic using the M74C would not be expected to affect air quality significantly, and levels would comply with air quality objectives designed to protect human health.

Greenhouse Gas Emissions

6.35 Road traffic emits quantities of carbon dioxide from petrol and diesel fuelled vehicles, which is one of the greenhouse gases thought to be responsible for climate change effects. Whilst emissions of CO2 have no implications for local air quality, a requirement of any new road scheme is a quantification of changes to emissions of CO2.

6.36 Emissions of CO2 are determined by fuel consumption and the kilometres travelled by the vehicle fleet. Lesser factors are the types of vehicles used and vehicle speeds. In the case of the M74 Completion, the emissions of CO2 are calculated using the outputs of the traffic model and the Design Manual for Roads and Bridges spreadsheet model. The ES, at pages K58 to K61, explains how the calculations were made and provides details of the results. Table 15.3 on page 208 of the ES summarises the predicted figures for each scenario and pollutant.

6.37 The "do minimum" analysis shows that CO2 emissions are likely to rise slightly for the road network considered, i.e. 8,250 road links across the wider study area, in the absence of the M74C. The predicted increase is 96,800 tonnes in the period 2001 to 2020, which represents a 4% increase. If the M74C is built, this increase would be expected to rise to 231,600 tonnes (10%). The difference between Do Minimum (no M74C) and Do Something (with M74C) is predicted to be an increase of 86,000 tonnes/year (3.8%) for 2010, and 134,800 tonnes/year (5.7%) for 2020. The whole of the Scottish transport sector in the year 2000 was responsible for CO2 emissions of 7.4 million tonnes. Accordingly, the additional annual contribution of the M74C in 2020 is estimated to be 1.8% of this total. While the increase in absolute terms is indisputable, the scale of the increase would be marginal, and there may well be an overall reduction resulting from other traffic management and transport policies.

6.38 Emissions of hydrocarbons, oxides of nitrogen, and particulate matter across the whole road network are expected to fall substantially between now and 2020, as a result of improved emissions control technology on vehicles. It could be argued that all these pollutants contribute to air pollution at a regional scale, through the formation of secondary particles, ground level ozone, or the phenomenon of acid deposition.

6.39 The presence of the M74C in 2020 would be expected to lead to very slight increases in total emissions of these pollutants over the wider study area considered, compared to the situation without the new motorway (see Table K6.8 of the ES). The differences would not be significant in the context of regional air pollution, and the TRA considers that the scale of the reductions that will be achieved over the period 2001- 2020 dwarfs the absolute values of these differences.

The Case for JAM74/FOE

6.40 In terms of air quality, the ADMS dispersion model used indicated an adverse impact on air quality within 100m of the M74C, with increases in both nitrogen dioxide and particulate matter. While these rises are small in themselves, when added to the current high pollutant levels in Glasgow city centre, the result may be non-compliance with air quality standards. About 89% of the route of the M74C lies in the area of worst pollution. At the western end, near the Kingston Bridge, there are recently built flats and flats under construction adjacent to the proposed route. The ES confirms that air quality objectives in this area are likely to be exceeded.

6.41 There is particular concern regarding pollutants and the incidence of respiratory disease, particularly asthma in children and young people. Research studies are cited to show the increasing number of asthma sufferers, and the impact in built up areas of high levels of sulphur dioxide, ozone, and nitrogen dioxide. While the causes of asthma may be open to debate, these pollutants are known to act as trigger factors. Accordingly, any increase in the level of the pollutants would result in an increased prevalence of asthma attacks.

6.42 In terms of climate change, the M74C is opposed WWF Scotland on the basis that it is inconsistent with stated UK government and Scottish Executive policies on reducing emissions. It was clear that the decision to proceed with the M74C had been taken before consideration of any scientific assessment of the likely impact of the M74C on climate change emissions. International commitments to which the government was bound include the Rio summit objective of cutting carbon dioxide levels to below 1990 levels by 2000 and the Kyoto protocol which requires a 12.5% cut in all 6 greenhouse gases to 1990 levels by the average of 2008 - 2012. Domestic commitments include a 20% cut in carbon dioxide by 2010 on 1990 levels and a 60% cut in pollution by 2050.

6.43 The UK government publication " Climate Change: The UK Programme" (2000) contained a section entitled the Scottish Climate Change Programme, with a Ministerial foreword. The programme presented the proposals to meet the various commitments, covering emissions from energy supply, business, transport, domestic, agriculture, forestry and land use, and the public sector. Recent analysis indicates the need for further radical measures if the 20% reduction in carbon dioxide emissions is to be achieved. The programme indicated that, in addition to the fuel duty escalator, further measures in the transport sector should produce 5.6MtC (32%) of the 17.75MtC reduction predicted for 2010. Actions by devolved administrations were expected to produce additional reductions, and Scottish Ministers have indicated that Scotland would make an "equitable contribution to the Kyoto commitment". The fuel duty escalator has now been set at 0% - in effect abandoned. The programme also recognised the importance of action at local level by local authorities. Only the City of Edinburgh Council is actively pursuing congestion charging which is unlikely to take effect until 2006.

6.44 Recent government statistics show a reduction in greenhouse gas emissions from the road transport sector in Scotland from 2.2MtC in 1990 to 1.9MtC in 2000, a 14% reduction due almost entirely to increasing fuel efficiency. These figures represent 14.5% and 13.1% of Scotland's total net emissions of carbon dioxide. Over the same 10 year period, total Scottish emissions have fallen by 5%. The conclusion therefore is that while emissions from the transport sector have declined, the additional measures to reduce emissions have been less effective. To make the "equitable contribution", a transport policy to secure further reductions is needed.

6.45 While proponents of the M74C claim that it would have only a minor impact on climate change emissions, in absolute terms it would increase carbon dioxide emissions. The claim is based on a "do minimum" scenario as opposed to a positive package covering demand restraint, improved public transport, and freight traffic measures. The ES indicates that traffic using the M74C would produce increases in carbon dioxide emissions of 24ktC in 2010 and 37ktC in 2020. These figures respectively represent 1.2% and 2% of the total road transport emissions of carbon dioxide for the whole of Scotland in the year 2000. The 2010 increase represents 0.15% of total Scottish emissions in that year. On the assumption that the 2010 target is met, the M74C would account for 0.2% of total Scottish emissions. The CSTCS indicated that the M74C would result in a minimum increase of 20% in carbon dioxide emissions. This would result in an increase in emissions of 128ktC in 2010, equivalent to 6.5% of total road transport emissions in 2000 and 1% of all carbon dioxide emissions in 2010 if the target for that year is met. A package of alternative strategic measures in and around the M74 corridor would lead to real reductions in emissions. On climate change grounds alone, the M74C should not proceed.

The Case for SAPT

6.46 The SAPT did not lead any technical evidence in this area, choosing to rely on cross examination. The significance of the impact of the ongoing shift from petrol to diesel fuel in road transport was questioned, the TRA acknowledging that the air quality studies had taken account of this factor, the main element of which related to use by HGVs. There would have to be a significantly greater shift for any noticeable impact on air quality. Stabilisation of traffic flows at 2001 levels would be beneficial in terms of air quality, but given the limitations of the modelling exercise, it would be impossible to simulate the extent of the impact. The description of the predicted increases in CO2 emissions for years 2010 and 2020 with the M74C in place - Table K6.7 of the ES - as "modest" was disputed, the increases in absolute terms being significant and running counter to government air quality objectives.

The Case for Dr M Hersh

6.47 Dr Hersh noted that there was considerable concern over the impact of air pollution on health, and children's health in particular. The increasing incidence of asthma in young people for reasons as yet unknown, while not necessarily attributable to pollutants such as PM10, would not be helped by more traffic pollution. Despite advances in engine technology, more vehicles would inevitably mean more pollution. Any improvements in air quality would be short term as the surface road network would soon fill up again. A precautionary approach to airborne emissions should apply.

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