7 Air Quality
7 Air Quality
7.1 Introduction
This section considers the potential health and wellbeing effects arising from changes in local air quality during the construction and operation of the proposed scheme.
Chapter 15 of the ES (Jacobs Arup, 2009a) has assessed the impacts of the proposed scheme on air quality resulting from changes in the levels of vehicle emissions on the local and wider local road network during operation. The air quality assessment compares predicted pollutant concentrations against EU air quality limit values (based on human health responses) and Scottish objectives, to determine whether the changes would result in significant impacts.
Construction impacts are assessed in Chapter 19 of the ES (Jacobs Arup, 2009a) and include dust generated by construction site activities and emissions from additional road traffic associated with construction.
The study area for the assessment of local air quality impacts from the proposed scheme is described in the ES and in simple terms includes all areas near roads likely to be subject to significant changes in traffic flow. It covers an area of approximately 9km (east-west) by 18km (north-south).
7.2 Evidence of Health Effects
This section is based on the information contained in Health Scotland’s Guidance on HIA of Transport Initiatives (Health Scotland, 2007). This guidance document provides a review of recent evidence linking transport related air pollutants (particulate matter - PM10 and PM2.5), nitrogen dioxide (NO2) and health.
Of relevance to this report is research on the small but measurable effects of low-level exposure to transport related pollutants. Long term exposure to low-level PM10 and PM2.5 has been linked with cardiovascular health effects.
The effects of NO2 are less well understood than the effects of particulates. NO2 is a precursor for the formation of ground-level ozone, which is linked with respiratory disease. Health Scotland’s evidence review suggests that the effects of NO2 are proportional to other transport related pollutants.
Health Scotland’s evidence review (2007) states that higher air pollution has been shown to potentially worsen the symptoms of pre-existing asthma. However, it has not been established that air pollution initiates the disease.
No research has been found linking construction dust with adverse health outcomes. It is generally accepted that particles greater than 10 microns in diameter (PM10) do not penetrate the lungs to cause respiratory health problems. However, dust can cause eye, nose and throat irritation and lead to deposition on cars, windows and property; this can be a cause of some anxiety and distress.
7.3 Existing Conditions
Air quality is monitored by local authorities and, where current or predicted exceedances of air quality objectives are identified, Air Quality Management Areas (AQMAs) are set up. The study area does not contain any AQMAs, and the nearest one is located approximately 8km east of the proposed scheme at St John’s Road in Edinburgh.
Details of the baseline levels of NO2 and PM10 in the study area are provided in Chapter 15 of the ES. These indicate that air quality in the study area is generally good. The annual average NO2 and PM10 concentrations are below the relevant air quality objective and limit values.
Air quality in the study area is good and the relative occurrence of pollutant related health problems is likely to be low. However, as shown by the research referred to in Health Scotland’s guidance, the low levels of air pollutants present within the study area have the potential to exert small adverse effects on the health of the population.
Through consultation with Fife and West Lothian NHS, it has been established that there are no areas of particular concern relating to existing respiratory health within the air quality study area.
7.4 Operational Impact Assessment
7.4.1 Air quality effects
The air quality impact assessment (Chapter 15 of the ES) has not identified any significant adverse impacts on air quality resulting from the proposed scheme. This assessment is based on:
- the degree of change in pollutant concentrations between the Do-Minimum and Do-Something scenarios; and
- comparison with EU air quality limit values and Scottish air quality objectives (based on factors including human health responses) for NO2, PM10 and PM2.5.
The air quality model predicted air pollutant levels at 51 receptor locations (these are properties selected on the basis of their proximity to affected road links), and also looked at the total population exposure across the study area.
With the exception of three properties located close to the northern and southern abutments, all future pollutant concentrations, both with and without the proposed scheme, are predicted to be lower than the existing baseline concentrations. This is due to predicted improvements in vehicle technology in the future and associated reductions in emissions from road transport.
When comparing the future Do-Something and Do-Minimum scenarios, the air quality assessment identified slight improvements in air quality around the existing Forth Road Bridge and slight deteriorations around the Main Crossing and new carriageway alignments.
The magnitude of change in NO2, PM10 and PM2.5 at modelled receptor locations was predicted to be ‘negligible’ or ‘extremely small’ for the vast majority of receptors and either ‘very small’, ‘small’, ‘medium’ or ‘large’ for a very small percentage of receptors." All areas are predicted to remain within the relevant health-based limit value for all pollutants.
The criteria used to define air quality effects are based on
recognised UK guidance on the assessment of air quality impacts.
For the purpose of this HIA the predicted levels of change are also
compared with evidence-based dose-response relationships for the
effects on health of low-level air pollutant
concentrations.
The predicted NO2, PM10 and PM2.5 concentrations (_g/m3) at the 51 modelled receptor locations for the Do-Something and Do-Minimum scenarios in the years 2017 and 2032 are set out in Tables 15.15, 15.18 and 15.22 of the ES. The strongest causal link between health and air pollutants relates to PM2.5 concentrations.
Table 15.22 of the ES (Jacobs Arup, 2009a) shows that the majority of modelled receptors will see either no change or a reduction in exposure to PM2.5, and predicted increases are identified at 6 receptors. The largest increase takes place at St Margaret’s Hope, a commercial building close to the new carriageway alignment near North Queensferry. In 2017, this receptor would see an increase of 0.6 _g/m3. The largest effect on a residential receptor is at St Margaret’s Hope Lodge, which would see an increase of 0.2 _g/m3. Concentrations at these receptors in 2017 will be lower than the base (2005) concentrations by 2.6 and 2.5 _g/m3 respectively.
The difference in PM2.5 concentrations between the Do-Minimum and the Do-Something scenarios at the above receptors is extremely small compared to the change identified as potentially having any health impacts. In addition, PM2.5 concentrations for both the Do-Minimum and Do-Something scenarios at the above receptors are significantly lower than the existing base concentrations, reducing risk of associated health effects. Furthermore it should be noted that differences measured at individual receptors do not indicate overall population exposure to background levels of PM2.5. Wider population effects are negligible, as illustrated by the modelled concentrations at other receptors in the vicinity of the proposed scheme.
On the basis of the above analysis it is concluded that changes in air quality associated with the proposed scheme will have no discernible impact on the health of the population within the study area.
7.4.2 Perceived Effects and Behaviours
The feedback received from the project consultation exercise has indicated that the local communities living close to the proposed scheme are concerned about the potential health effects of additional traffic, and that this issue is a source of anxiety for individuals within the community. In addition to causing anxiety, concern over air quality has the potential to discourage some people from utilising outdoor areas such as gardens, parks and footpaths, thereby missing out on the benefits associated with outdoor activities.
Asthma has been raised as a particular concern by local people living in close proximity to the proposed scheme. Whilst there is no evidence that road traffic emissions can initiate asthma, it may exacerbate pre-existing symptoms. Given the low level of change in traffic emissions, it is considered that the scheme will have no discernible impacts on asthma.
7.5 Construction Impact Assessment
7.5.1 Construction Traffic Emissions
The ES has identified the assumed haulage routes leading to the three construction sites. The intention is to keep construction traffic on the main routes that are designed for large flows and heavy loads and to avoid sensitive residential areas where possible. The exact routing restrictions would be discussed with the local authorities. As described in Section 6 of this report, the current assumption is that construction sites would be located at Ferrytoll Junction, South Queensferry / Echline and M9 Junction 1a.
The assessment of construction traffic emissions presented in Chapter 19 of the ES has identified the sensitive receptors closest to these routes and calculated the NO2 and PM10 contributions from construction traffic, using worst case assumptions. The magnitude of change identified ranges from very small to medium, with the largest impacts occurring around the M9 Junction 1a construction site. These effects would not result in any exceedances of the health-based National Air Quality Objectives. Given the temporary nature of the increases in NO2 and PM10 from construction traffic, there would be no effect on average annual concentrations in the long term and therefore no adverse health effects are expected.
The feedback from public consultations undertaken by Transport Scotland has indicated that local people are concerned about the impacts of construction traffic, including traffic emissions. There is therefore a potential for concerns about the health effects of construction traffic emissions to cause anxiety among the local community.
7.5.2 Construction Dust
As stated in Section 7.2 above, dust is not linked with respiratory disorders. Construction dust can adversely affect the wellbeing of individuals and communities in terms of:
- enjoyment of outdoor spaces (with potential knock on effects such as a temporary reduction in physical activity or social interaction);
- anxiety relating to perceived health effects; and
- potential minor irritation of the throat and eyes.
Monitoring of construction sites in the UK indicates that any significant elevation in dust deposition rates is usually limited to within 200m of the construction works boundary. Within this distance, there is potential for dust nuisance impacts on sensitive receptors such as homes or schools.
Chapter 19 of the ES provides an assessment of the potential for dust nuisance based on the number of dust sensitive receptors and the distance from the construction activity, as well as the nature and duration of the works. It should be noted that although the Main Crossing works in total are estimated to last more than five years, the duration of land based and potentially dust generating construction works at any one location is likely to be far shorter.
There are various activities with the potential to generate dust during the construction programme. These include topsoil stripping and excavation and handling of soils and other materials, demolition of existing structures at South Queensferry and Junction 1a and blasting for rock cuttings near Ferrytoll. The number of sensitive properties within 200m of these activities has been counted and is shown in Chapter 19 of the ES and in Table 9 below.
Table 9: Number of sensitive receptors within 200m of dust generating activities
| Distance from site boundary |
No of sensitive receptors |
||
|---|---|---|---|
| Ferrytoll |
South Queensferry |
M9 Junction 1A |
|
| 0-25m |
2 |
66 |
35 |
| 25-50m |
19 |
86 |
27 |
| 50-100m |
110 |
190 |
48 |
| 100-200m |
297 |
520 |
127 |
| Total |
428 |
862 |
237 |
Source: ES Chapter 19 (Jacobs Arup, 2009a)
The receptors comprise residential properties, with Dalmeny Primary School also located approximately 50m from the proposed construction works at South Queensferry. Although Dalmeny Primary School is situated close to the edge of the works area, it is on the eastern periphery of the proposed works, where the risk of dust-generating activities is relatively low.
The ES and CoCP have proposed a number of mitigation measures to minimise the effects of dust. These relate to the way that construction activities are undertaken and managed, and include measures to prevent adverse effects on sensitive receptors such as Dalmeny Primary School. Dust control measures would be set out in a Dust and Air Quality Management Plan prepared as part of the contractor’s Environmental Management Plan.
Properties within 200m of the proposed works may suffer from the effects of dust on a short to medium term basis. Outdoor recreational areas and public footpaths may also be affected.
7.6 Mitigation Measures
7.6.1 Operational Phase
No recommendations are made in the ES in relation to mitigation for health impacts relating to operational traffic emissions as the assessment considers the proposed scheme will not have any measurable effect on health.
7.6.2 Construction Phase
The Contractor will be required to apply best practice mitigation measures to control dust. The CoCP includes a section on Dust and Air Pollution. This requires the Contractor to produce an Air Quality Management Plan describing the dust and air pollution control measures to be used during the construction works. This would include measures to prevent or counteract the effects of nuisance caused by construction works and to avoid significant adverse effects of emissions of NO2 and PM10 in relation to compliance with local air quality objectives. Dust and air pollution monitoring measures will also be detailed.
A dedicated Community Liaison Officer would be available throughout the construction period to respond quickly to any complaints with regard to construction dust and emissions. The Community Engagement Requirements within the CoCP include a requirement for the Contractor to take reasonable steps to notify occupiers of nearby properties two weeks in advance of the nature and anticipated duration of planned construction works that may affect them. The notification will also provide details of the enquiries and complaints procedure.
7.7 Assessment of Health Impacts
The effects on health have been assessed according to the criteria set out in the Merseyside Guidelines (see Section 4.6).
The available evidence (see Section 7.2) indicates an identified causal link between levels of particulate matter, nitrogen oxides and health. The degree of certainty is therefore considered to be probable. For other anxiety related stress issues associated with air quality impacts, the degree of certainty is considered to be speculative.
Changes in air quality in the study area as a result of the operation of the proposed scheme are generally predicted to be very small, and would not give rise to any health effects.
During construction, the perceived changes in air quality as a result of construction activities may contribute towards anxiety and stress related health issues. Although there is a risk of dust nuisance for residents and sensitive users in close proximity to the construction works, changes in predicted nitrogen dioxide concentrations and fine particulate matter concentrations are low.
The magnitude of health effects during both construction and operation are considered to be negligible for operation and negligible to minor during construction.
7.8 HIA-Specific Mitigation
The following mitigation measures have been identified:
- When notifying communities of planned construction works as required by the CoCP, the Contractor will provide information on proposed air quality monitoring and any other mitigation proposed for during the works.
- The Contractor will be required to demonstrate a commitment to its wider social responsibilities, for example through participation in the Considerate Constructor’s scheme.