A66 Northern Trans-Pennine Route Upgrade

Air quality

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This section summarises the preliminary assessment findings at this point in the EIA process for air quality, based on PEI Report Chapter 5: Air Quality.


Air quality in the area around the project is considered to be good. This is confirmed by the fact that there are no Air Quality Management Areas (AQMA) close to the project, with the nearest being over 30km from the A66 (Durham and Chester-le-Street AQMA). Eden District Council have been considering the potential for a future AQMA to be declared at Castlegate, Penrith for NO2. AQMA are areas which the local authority has identified as requiring management to achieve desired air quality objectives.

The predicted Defra background concentrations along the project route are well below the annual mean objectives for NO2 and PM10. For particulate matter (PM10 and PM2.5) there are no AQMAs designated or likely to be designated for an exceedance of Air Quality Objectives (AQO) and Air Quality Limit Value (LV) thresholds in the air quality study area. There are also no exceedances of the annual mean NO2 AQO and LV threshold within the air quality study area.

Although the area around the project is predominantly rural, there are houses, schools, hospitals and ecological designated species and habitats which could be affected by changes in air quality.


During construction, potential air quality effects may arise from emissions of construction dust and PM10. These emissions occur as a result of construction activities such as demolition, earthworks, construction and trackout. The quantities of each depend on the scale and intensity of the construction works.

Dust has the potential to cause nuisance to property, and very high levels of soiling can affect plants and ecosystems. There is the potential for dust impacts to receptors within 200m of construction and haulage routes associated with the project.

There are a number of people which could be directly affected by dust nuisance associated with the project or construction vehicle traffic. Best practice construction dust control measures and standard mitigation measures can limit these effects.

Detailed information on construction activities was not available at the time of writing, and the assessment is based on high level information about likely construction activities and key construction locations such as compounds. The Construction Method Statement (a first draft of which was produced after the assessment was completed and is available as part of the consultation materials) will be used to inform the detailed assessment for construction dust to be presented in the ES.

Preliminary construction assessment

Construction Dust

  • Mitigation to reduce construction dust impacts to a negligible level will be included in the EMP. This includes development of a dust management plan with measures to monitor effectiveness of mitigation, daily on site and off site inspections and keeping a record of complaints/exceptional dust events. With appropriate best practice mitigation measures in place the potential impacts from construction are considered to be not significant.

Construction Traffic

  • Whilst the construction phase is temporary in nature, due to the likely number of construction vehicles that will be required, duration of works and the presence of sensitive human and ecological receptors near to roads likely to be affected, there is the potential for significant effects to occur. Further work will be undertaken to characterise these potential impacts as part of the EIA as more detailed data becomes available.


During operation, changes to the road network will result in changes to traffic flow, speed and fleet composition. Traffic flows are likely to increase due to the improved desirability of the route, however speeds are likely to increase due to increased capacity and reduced congestion. These changes will impact on emissions of NOX and PM10. As a result, pollutant concentrations at receptors within the air quality study area will be affected by the project. These changes may result in permanent improvements and deteriorations in local air quality depending on location.

Preliminary operation assessment

Human Receptors

  • A small number of receptors are predicted to experience a small adverse change in air quality, however no likely significant effects are anticipated as the level of change and the number of receptors affected is lower than the level of significant effect defined in relevant guidelines. The locations of these receptors are detailed within Section 5.10 of PEI Report Chapter 5: Air Quality.

Habitat Sites

  • Likely significant adverse effect due to nutrient nitrogen deposition at Stephen Bank Road Verge Local Wildlife Site (LWS)
  • Likely significant beneficial effect due to a reduction in nutrient nitrogen deposition at Chapel Wood Ancient Woodland (AW)
  • Possible likely significant increases in nutrient nitrogen deposition are predicted at 15 designated ecological sites, subject to further assessment. These sites include:
    • North Pennine Moors Special Protection Area (SPA)
    • North Pennine Moors Special Area of Conservation (SAC)
    • Argill Woods and Pasture Site of Special Scientific Interest (SSSI)
    • Augill Valley Pasture SSSI
    • Bowes Moor SSSI
    • Pallet Hill LWS
    • Stephen Bank Road Verge LWS
    • Augill Beck Wood AW
    • Augill Bridge Wood AW
    • Deepdale Wood AW
    • Graham's Gill/Jack-Wood AW
    • Newbiggin Wood AW
    • Oglebird Plantation AW
    • Raughtonguill Wood AW
    • Thorgill Wood AW

Highways England is developing a tool for determining the additional contribution of ammonia (NH3) emissions from vehicles to deposited nitrogen. It is expected that this method will be available for use at the ES stage and therefore the potential ecological impacts will be updated accordingly.

The ongoing EIA will consider appropriate mitigation, which might include things like a dust management plan to control dust emissions during construction, to address likely significant effects identified at this preliminary assessment stage.