Proposed Residential Development Land at Baldock, Hertfordshire. Air Quality Assessment Site

Transcription

1 Proposed Residential Development Land at Baldock, Hertfordshire Air Quality Assessment Site July 2008

2 Hertfordshire County Council i CONTENTS 1.0 INTRODUCTION Structure of Report RELEVANT AIR QUALITY LEGISLATION AND GUIDANCE Air Quality Strategy for England, Scotland, Wales & Northern Ireland Planning Policy Statement 23 (PPS23) NSCA Planning for Air Quality Guidance Local Authority Information: North Hertfordshire District Council (NHDC) BASELINE Description of site and locality Existing Air Quality Environment Monitoring Data from NHDC Nitrogen dioxide survey undertaken by METHODOLOGY Consultation with NHDC Environmental Health Scale of Assessment Description of potential impacts ASSESSMENT OF IMPACT, MITIGATION AND RESULTS Construction Phase: Dust Operational Phase Mitigation CONCLUSIONS TABLES Table 3-1 NO 2 Diffusion Tube Monitoring Data (µg/m 3 ) Annual Average Table 3-2 NO 2 Diffusion Tube Monitoring Data (µg/m 3 ) Annual Average Table 3-3 NO 2 Diffusion Tube Monitoring Data (µg/m 3 ) Annual Average Table 3-4 NO 2 Diffusion Tube Monitoring Data (µg/m 3 ) Survey Table 5-1 Baseline Traffic Counts Table 5-2 Predicted Baseline Air Quality Table 5-3 Development Traffic Table 5-4 Predicted Air Quality Whitehorse Street Table 5-5 Cumulative Development Traffic Table 5-6 Predicted Air Quality South Road Table 5-7 Predicted Air Quality Whitehorse Street Table 5-8 Predicted Air Quality Clothall Road Table AQ-1 Background Pollutant Concentrations Table AQ-2 Background Pollutant Concentrations Figure 1 Figure 2 Figure 3 Appendix A Appendix B Appendix C DRAWINGS Proposed Development Sites NHDC Diffusion Tube Monitoring Locations Survey Diffusion Tube Monitoring Locations APPENDICES Air Quality Standards and Objectives The UK Air Quality Strategy NSCA Significance Criteria Background Pollutant Concentrations from NETCEN T:\New Projects\404 Redditch\ Herfordshie CC\ Baldock\ R VG Land at Baldock AQ Draft - Ass Site 2 FINAL.doc

3 Hertfordshire County Council INTRODUCTION Consulting has been commissioned to provide an assessment of air quality associated with residential developments at Baldock, Hertfordshire. Four sites are under consideration: site 1 is located adjacent to the Baldock Bypass and split into 3 sections; site 2 is located adjacent to Bygrave Road and split into 2 sections; site 3 is located adjacent to North Road; and site 4 is located adjacent to Royston Road. This report details the air quality assessment associated with the residential development of Site 2. This assessment involves a review of the existing background air quality and the potential changes in air quality concentrations due to the proposed development. From this review, the need for further air quality monitoring, and screening or detailed modelling assessments is identified. A qualitative assessment of the likely dust impacts from construction has also been undertaken. 1.1 Structure of Report The remainder of this report is structured as follows: section 2 outlines the UK air quality legislation and guidance; section 3 details the existing air quality and the development; section 4 details the techniques utilised in undertaking the assessment; section 5 presents the findings of this assessment; and section 6 concludes the study. Supporting information is contained within the Appendices.

4 Hertfordshire County Council RELEVANT AIR QUALITY LEGISLATION AND GUIDANCE 2.1 Air Quality Strategy for England, Scotland, Wales & Northern Ireland The Air Quality Strategy for England, Scotland, Wales and Northern Ireland (UKAQS) 1 was first published in 2000 and updated with an addendum in February Following extensive consultation and developments in the applicable Regulations, the Strategy has been updated and a new Air Quality Strategy was released in July The UKAQS sets out a comprehensive strategic framework within which air quality policy will be taken forward in the short to medium term, and the roles that Government, industry, the Environment Agency, local government, business, individuals and transport have in protecting and improving air quality Local Authority Air Quality Review and Assessment Part IV of the Environment Act 1995 requires local authorities to review and assess existing and predict future air quality in their areas as part of a rolling review & assessment process. At the end of the first round a number of local authorities designated Air Quality Management Areas (AQMAs) in which exceedances of one or more of the air quality objectives have been predicted. AQMAs cover the area in which exceedances have been predicted, and once designated; the local authority must then draw up an Air Quality Action Plan (AQAP) setting out the measures it intends to take in pursuit of achieving the air quality objectives in the AQMA. The core guidance documents for use by persons involved in Local Air Quality Management (LAQM), or considering the impacts of a development with the potential to impact on air quality as covered by LAQM, are LAQM TG (03) 2 and LAQM PG (03) 3. Where the assessment involves the potential impact of traffic, the Design Manual for Roads and Bridges (DMRB) 4 air pollutant screening tools may also be used. LAQM Technical Guidance (08) 5 Consultation Document was made available on the 4 th July Planning Policy Statement 23 (PPS23) Planning Policy Statement PPS23 provides advice relating to issues governing whether development would be advisable. This includes development constraints and opportunities as related to air quality and was published in November PPS23 states that the existing, and likely future, air quality in the area [of proposed development plans], including any AQMAs or other areas where air quality is likely to be poor should be considered in the preparation of development plan documents and may also be material in the consideration of individual planning applications where pollution considerations arise. 1 Air Quality Strategy for England, Scotland, Wales and Northern Ireland, July 2007, 2 Local Air Quality Management Technical Guidance, DEFRA, Local Air Quality Management Policy Guidance, DEFRA, Design Manual for Roads and Bridges, Volume 11, HA207/07- Air Quality, Highways Agency, Local Air Quality Management Technical Guidance, DEFRA, 2008

5 Hertfordshire County Council This Planning Policy Statement also advises that: more weight will generally need to be given to air quality considerations, for example, where a development would have a significant impact on air quality inside, or adjacent to, an AQMA (Air Quality Management Area) However, Appendix 1G of PPS23 the same Statement also warns against the sterilisation of an area due to rejection of all development on air quality grounds and states that the significance of one consideration relative to another will vary dependent upon circumstances. 2.3 NSCA Planning for Air Quality Guidance Guidance was issued by the National Society for Clean Air (NSCA) relating to Air Quality considerations within the planning process for use by local planning authorities and developers alike was updated in November In this guidance: Development control - planning for air quality 6, criterion are detailed which identify the need for an Air Quality Assessment, the type of Air Quality assessment required, and the significance of any predicted impact. 2.4 Local Authority Information: North Hertfordshire District Council (NHDC) The 1995 Environment Act required the District Council to undertake an Updating and Screening Assessment (USA) in A Detailed Assessment was required for a number of streets within the District and was published in September Development control - planning for air quality 2006 Update, NSCA, 2006

6 Hertfordshire County Council BASELINE 3.1 Description of site and locality Baldock (population ) is a small town north of Stevenage, within North Hertfordshire District Council (NHDC). No ecologically important sites are located in the local area. There are four schools (primary and secondary) and a health facility located in Baldock town centre adjacent to the local road network. There is a football ground located along the A507 Clothall Road. Site 2 is divided into 2 areas. Site 2A is situated north of Bygrave Road and Site 2B is situated south of Bygrave Road. The dwelling estimate is 388 units in total. Site 2A is bounded by an existing residential area to the west, agricultural land to the north and east and Bygrave Road to the south. Site 2B is bounded by an existing residential area to the west, agricultural land to the east, Bygrave Road to the north and a railway line to the south. The town is serviced by the Cambridge to London rail service with new electric trains. The worst case situation both 2A and 2B in operation has been considered for this assessment. DMRB states that beyond 200m, the contribution of the road traffic emissions to local air quality is insignificant. The study area for the assessment of potential effects from vehicle emissions on local air quality can therefore be defined as a corridor extending up to 200m either side of all affected roads. The A1(M) is located over 800 metres from Site 2 and the related traffic would not affect this site in terms of air quality. The proposed site locations are presented in Figure Existing Air Quality Environment Information provided by NHDC has confirmed the following in relation to the NHDC Local Air Quality Management Review & Assessments: long-term nitrogen dioxide diffusion tube monitoring data exists for 27 locations in the NHDC area. Four of these locations are located within the town centre and residential areas and are presented in Figure 2; the Council operates a mobile monitoring situated in Breachwood Green. This site is a rural background location and is near to Luton Airport. Nitrogen oxides (NO & NO 2 ) and particulate matter (PM 10 ) are monitored at this location; and there are no significant industrial processes close to the sites which could cause exceedance of air quality objectives. 3.3 Monitoring Data from NHDC Examination of monitoring data within NHDC identified in the NHDC Updating and Screening Assessment (USA) 8 that nitrogen dioxide (NO 2 ) concentrations exceed the Air Quality Strategy (AQS) annual mean objective for this pollutant (40 µg/m 3 ) at roadside monitoring locations within the town centre and it was concluded that a Detailed Assessment was required. The NHDC USA concludes that there were no exceedences of the 2005 AQS Updating and Screening Assessment (Amended), Consultation Draft, North Hertfordshire District Council, 2006

7 Hertfordshire County Council annual objective for PM 10 (40 µg/m 3 ) at Breachwood Green; currently the only location in borough that monitors particles. Bureau Veritas, under instruction from NHDC, undertook the LAQM Detailed Assessment (DA) in focusing on 2 areas of concern in Hitchin and the Hitchin Street / Whitehorse Street junction in Baldock. The conclusion of the DA is that modelling predictions show exceedences of the AQS objective for NO 2 for 2010 at the Hitchin Street / Whitehorse Street junction. It was recommended that NHDC declare an AQMA at this location and further diffusion tubes in the area are to be installed to confirm the modelling Nitrogen dioxide monitoring data The NHDC USA diffusion tube monitoring results for 2005, at the four locations within the town centre and Clothall Common residential area, are presented in Table 3-1 and these locations are shown in Figure 2. Diffusion tubes are categorised as an indicative monitoring technique and uncertainty levels are +/- 25%. The results of the diffusion tube monitoring shows that the 2005 background level of NO 2 at Clothall Road was close to the AQS annual mean objective level of 40 µg/m 3, and an exceedence was indicated at Whitehorse Street (shown in bold). Both these locations are kerbside sites and as reported in the NHDC USA, do not represent relevant public exposure. The closest diffusion tube to Site 2 is located in Grosvenor Road (NH09) and is approximately 150 metres away. Table 3-1 NO 2 Diffusion Tube Monitoring Data (µg/m 3 ) Annual Average 2005 Monitoring Location Address Type Coordinates NO 2 concentration (µg/m 3 ) NH09 Grosvenor Road, Baldock Intermediate , NH59 NH04 Clothall Road, Baldock Kerbside , NH61 NH53a Whitehorse Street, Baldock Kerbside , NH55 Merchants Walk, Baldock Kerbside , NETCEN (2005) a) 17.8 Air Quality Objective 40.0 a) Data obtained for the site location (524500, ) from the NETCEN website: The NHDC DA diffusion tube monitoring results for 2006, at the three locations within the town centre are presented in Table North Hertfordshire District Council, LAQM - Detailed Assessment, Bureau Veritas, September 2007

8 Hertfordshire County Council Table 3-2 NO 2 Diffusion Tube Monitoring Data (µg/m 3 ) Annual Average 2006 Monitoring Location Address Type Coordinates NO 2 concentration (µg/m 3 ) NH09 Grosvenor Road, Baldock Intermediate , NH59 NH04 Clothall Road, Baldock Kerbside , NH61 NH53a Whitehorse Street, Baldock Kerbside , NETCEN (2006) a) 14.6 Air Quality Objective 40.0 a) Data obtained for the site location (525500, ) from the NETCEN website: Diffusion tube results obtained from HBAPMN are presented in Table 3-3 This data represents diffusion tube data results for 2007 Diffusion tube results obtained from the Herts and Beds Air Pollution Monitoring Network (HBAPMN) 10 are presented in Table 3-2 This data represents diffusion tube data results for The Merchants Walk diffusion tube site was closed in 2006 after the Baldock Bypass was completed. Table 3-3 NO 2 Diffusion Tube Monitoring Data (µg/m 3 ) Annual Average 2007 Monitoring Location Address Type Coordinates NO 2 concentration (µg/m 3 ) NH09 Grosvenor Road, Baldock Intermediate , NH59 NH04 Clothall Road, Baldock Kerbside , NH61 NH53a Whitehorse Street, Baldock Kerbside , a) NETCEN (2007) b) 16.9 Air Quality Objective 40.0 a) Low capture rate (2 months out of 12) b) Data obtained for the site location (524500, ) from the NETCEN website: It can be seen that Whitehorse Street, in the town centre, exceeded the AQS annual mean objective level in 2005, 2006 and Nitrogen dioxide survey undertaken by A short term diffusion tube survey was undertaken by personnel between 2 nd April 2008 and 3 rd July 2008 in accordance with TG(03) and the AEA Energy and Environment s Practical Guidance Diffusion Tubes for Ambient NO 2 Monitoring Herts and Beds Air Pollution Monitoring Network, 11 Diffusion Tubes for Ambient NO 2 Monitoring: Practical Guidance for Laboratories and Users, AEA Energy and Environment, February 2008.

9 Hertfordshire County Council Monitoring locations were located adjacent to the Baldock Bypass and are presented on Figure 3. Breachwood Green as stated earlier is a mobile monitoring unit and classed as a rural background and therefore 3 diffusion tubes were co-located at this site. The diffusion tubes were supplied and analysed by Gradko International. The results of the diffusion tube survey are presented in Table 3-4. Table 3-4 NO 2 Diffusion Tube Monitoring Data (µg/m 3 ) Survey 2008 Monitoring Location Bias Adjusted* Annual Mean 1A & 1B A & 2B A & 3B A & 4B A & 5B A, 6B & 6B 14.3 The AEA bias adjustment factor spreadsheet 12 was used to obtain the Bias factor. The Annual means for each tube have been estimated following Box A1.3 in TG (03) PM 10 monitoring data PM 10 is monitored at Breachwood Green. This is currently the only location in borough that monitors particles. NHDC s USA stated that there are no areas with unusually high proportion of buses or HGV s, so no further assessment for this pollutant was required. It is therefore concluded that the town does not suffer from high levels of PM AEA Bias Adjustment facto spreadsheet, April 2008

10 Hertfordshire County Council METHODOLOGY 4.1 Consultation with NHDC Environmental Health Consultation with Victor Quashie, Environmental Protection Manager for NHDC, was undertaken and the following information was provided: NHDC do not have any specific guidance relation to air quality impacts from construction sites and are satisfied that the construction impacts are assessed with the Greater London Authority guidance 'London Best Practice Guidance: The control of dust and emissions from construction and demolition' 13 ; NHDC does not have any specific guidance relation to air quality impacts (traffic) from development and are satisfied that operating impacts are assessed with the NSCA (Environmental Protection UK) guidance: Development control - planning for air quality 14 ; a Detailed Assessment has been undertaken at a number of streets and a recommendation has been made to declare an Air Quality Management Area (AQMA) along Whitehorse Street within the town centre; there are no specific local plan policies in relation to air quality; and an area within the town centre has been planned to be pedestrianised with work commencing in 2008 and to be completed by April Scale of Assessment NSCA (2006) describes the need for an Air Quality Assessment as follows: Developments will require an air quality assessment where a significant change in air quality is expected or anticipated. The change will include both construction and operational impacts. There will also be a need to assess air quality implications where a significant change in relevant exposure (i.e. introduction and increase) is anticipated, such as the development of residential properties in an area of already poor air quality. Professional judgement will be required for deciding when an air quality assessment is necessary, as it is not possible to apply an exact and precise set of criteria to all development proposal situations. However, the following criteria may help define when an air quality assessment should be considered necessary: proposals that will result in increased congestion, a change in either traffic volumes typically a change in annual average daily traffic (AADT) or peak traffic flows of more than +/- 5% or +/-10%, depending on local circumstances or a change in vehicle speed (typically of more than +/-10 kph), or both, usually on a road with more than 10,000 AADT. This is based on the sensitivity of emission rates to traffic speeds and volumes, and roads below 10,000 AADT normally having a minimal impact on local air quality. 13 The control of dust and emissions from construction and demolition Best Practice Guidance, Greater London Authority and London Councils, November Development control - planning for air quality 2006 Update, NSCA, 2006

11 Hertfordshire County Council proposals that would significantly alter the traffic composition (i.e. increase in the proportion of HGVs) in an area (e.g. bus stations, HGV parks, increase delivery traffic). proposals that include new car parking e.g. >300 spaces or an increase in current parking provisions by, for example 25%, although account should be taken of car park turnover, i.e. the difference between short-term and long-term parking or new coach or lorry parks. developments located in, or which may affect, sensitive areas (e.g. ecological sites) or areas of poor air quality (including AQMAs), where either direct emissions to air occur, or where any of the preceding criteria are met. introduction of new exposure close to existing sources of air pollutants, including road traffic, industrial operation, agricultural operations etc. potential impacts from construction on nearby residents. developments that would give rise to significant dust emissions in area where people and/or commercial activities would be exposed. 4.3 Description of potential impacts During the construction stage, there is potential for the generation of construction dust (primarily coarse, or deposited dust). Construction traffic associated with the development will contribute to existing traffic levels on the surrounding road network. Once the development has been completed the traffic generated by it may have an impact on local pollution levels, both on and around the proposed development site. The main pollutants of concern for road traffic are nitrogen dioxide (NO 2 ) and particulate matter (PM 10 ). These are the two most likely to result in exceedences of the relevant air quality standards or objectives in urban areas where road traffic is the dominant source of local air pollution. Descriptors for Impact Magnitude and Impact Significance in Air Quality Assessments from the NSCA Guidance are reproduced in Appendix B.

12 Hertfordshire County Council ASSESSMENT OF IMPACT, MITIGATION AND RESULTS 5.1 Construction Phase: Dust Construction activities with the potential to generate dust at the site can be divided into the following operations: haulage routes and vehicles; earthworks and excavation; construction operations; storage of materials; disposal of materials; and internal / external finishing and refurbishment Good operational management of the construction operations will ensure that levels of dust released from the development site are minimised. This may be formalised through adoption of a Construction Environmental Management Plan (or similar), if appropriate, and may include (for example): sweeping of access routes; application of speed limits; dampening down with water sprays / bowsers; and wheel and vehicle cleaning. There are a large number of documents available which detail potential techniques for dust mitigation. This includes the Greater London Authority guidance 'London Best Practice Guidance: The control of dust and emissions from construction and demolition' 15. Given the mitigation techniques available it is considered that dust from construction will be controlled. On this basis, it is predicted that the impact of dust during construction operations will be acceptable. The total number of vehicles associated with the construction phase is unknown at this stage, although the amount of HGV s is unlikely to be a significant number as outline in DMRB Operational Phase Baseline Predictions at Development Site An assessment of the baseline air quality has been undertaken to assess the air quality at the development site location to identify any potential air quality constraints. Manual traffic counts have been undertaken by Hertfordshire County Council at various times in 2007 (March, October and December) and in June The Annual Average Daily Traffic (AADT), speed limits and percentage Heavy Duty Vehicles (vehicles greater than 3.5 tonnes Gross Vehicle Weight) of the main road within Baldock which could potentially affect the air quality at the potential site is detailed below in Table The control of dust and emissions from construction and demolition Best Practice Guidance, Greater London Authority and London Councils, November DMRB Volume 11, HA207/07- Air Quality, Highways Agency, 2007

13 Hertfordshire County Council Table 5-1 Baseline Traffic Counts 2007 Road Link Distance to link centre AADT Speed (kph) % HDV Site 2A & 2B Bygrave Road Site 2B Royston Road Speeds were unavailable on Royston Road and have been based on the speed limit of the closest section to Site 2. Predictions of baseline air pollutant concentrations have been made using the DMRB Screening Method 17 using the latest version of the Screening Spreadsheet (version 1.03c July 2007). A new conversion factor for predicting roadside NO 2 from roadside NO X has been published (March 2007) 18 and this has been utilised in the predictions. Information on background levels of pollutants in the study area was obtained from the 1km x 1km database available on the national air quality archive 19. These were then adjusted for each year of assessment to estimate likely changes with time, using guidance provided in TG(03). The background concentrations used in the DMRB predictions are reproduced in Appendix C. Revised background concentration maps of NO X, NO 2 and PM 10 for all years from 2006 to 2020 are due to be available in late 2008 as stated in the draft TG(08), although at the time of writing these maps are not available. The predicted values represent the worst case scenario. The distances used in the DMRB Screening Method are from the road link centre to the kerbside and façade. The results are displayed below in Table 5-2. Table 5-2 Predicted Baseline Air Quality 2007 Site Worst-case location Closest Links NO 2 Annual Mean (µg/m³) Annual Mean (µg/m³) Site 2A & 2B Kerbside Bygrave Road Site 2A & 2B Façade Bygrave Road Site 2B Southern extent Royston Road National Air Quality Objective level PM 10 Days > 50 µg/m³ It can be seen that based on the baseline traffic counts, the baseline air quality at the proposed Site is well below the Air Quality Objectives. Although traffic flows are expected to rise in the future, vehicle emission technology is expected to improve in the future and emission rates are expected to fall. 17 Design Manual for Roads and Bridges (DMRB), Highways Agency, July 2007, 18 Calculation of Roadside NO x from Roadside NO 2 - Taking Account of Trends up to UK National Air Quality Archive,

14 Hertfordshire County Council Development Traffic Impacts on the Existing Network In agreement with NHDC and in accordance with the NSCA guidance, a simple screening comparison of with development traffic flows has been completed to allow the scale of traffic impact to be illustrated. The traffic data has been derived from the Transport Assessment (TA) updated for the latest Master Plan for the site. Traffic accessing and leaving the development site will be small in comparison to the number of vehicles using the surrounding road network as discussed in the TA and is summarised below in Table 5-3. The AADT from Site 2A and Site 2B have been added together as if both sites are in operation. Road Link Table 5-3 Development Traffic 2009 Baseline AADT Development AADT Total AADT % Increase Bygrave Road % Wallington Road % Clothall Road % Royston Road % South Road % North Road % Whitehorse Street % High Street % Hitchin Street % Baldock Bypass % From a review of the traffic associated with the development the road link which is of greatest concern is Whitehorse Street. The other roads on the network which are greater than 10,000 AADT increase by less than 3%. DMRB modelling has been undertaken for Whitehorse Street, which is within the proposed AQMA, for the opening year Background pollutant concentrations used in the DMRB modelling are reproduced in Appendix C. Receptor locations used to predict the annual mean pollutant concentration are as follows; 5m from the edge of the road, to represent roadside; and 10m from the edge of the road, to represent the location of building façades. The results are displayed below in Tables 5-4 and 5-5.

15 Hertfordshire County Council Table 5-4 Predicted Air Quality Whitehorse Street Without Development 2009 With Development 2009 Difference Whitehorse Street Predicted Environmental Concentration (µg/m³) (µg/m³) (%) Annual NO 2 Concentration Kerbside % Façade % National Air Quality Objective Annual PM 10 Concentration Kerbside % Façade % National Air Quality Objective Number Days PM 10 > 50 µg/m³ Kerbside % Façade % National Air Quality Objective The traffic associated with Site 2 (2A and 2B) has been predicted at Whitehorse Street and does not increase the level of NO 2 and PM 10 significantly. The increase in NO 2 and PM 10 due to the additional development traffic has been compared to the NSCA air quality significance criteria. NO 2 Predicted Impacts The magnitude of change for NO 2 is Very Small for Whitehorse Street. Due to Whitehorse Street being within the soon to be declared AQMA, this change is classed as a slight impact. PM 10 Predicted Impacts The magnitude of change for PM 10 is Extremely Small for Whitehorse Street. This change is classed as a negligible impact Cumulative Impacts As stated earlier in the report, Site 2A and 2B are part of a larger scheme which includes 3 other potential sites with associated development traffic. Table 5-5 below shows the associated traffic from all 4 sites if they were in operation.

16 Hertfordshire County Council Road Link Bygrave Road Wallington Road Table 5-5 Cumulative Development Traffic 2009 Baseline AADT Site 1 Site 2 Site 3 Site 4 Total Development AADT Total AADT % Increase % * % Clothall Road % Royston Road * % South Road * % North Road % Whitehorse Street % High Street % Hitchin Street % Baldock Bypass % *worst case from Site 1B Option A - With School scenario From a review of the traffic associated with the developments the road links which show the greatest concern are South Road, Clothall Road and Whitehorse Street. The other roads on the network which are greater than 10,000 AADT increase by less than 10%. South Road and Clothall Road are mainly affected by development traffic associated with Site 1. Whitehorse Street is mainly affected by development traffic associated with Site 2. DMRB modelling has been undertaken for South Road, Whitehorse Street, which is within the proposed AQMA and Clothall Road, for the opening year The results are displayed below in Tables 5-6, 5-7 and 5-8.

17 Hertfordshire County Council Table 5-6 Predicted Air Quality South Road Without Development 2009 With Development 2009 Difference South Road Predicted Environmental Concentration (µg/m³) (µg/m³) (%) Annual NO 2 Concentration Kerbside % Façade % National Air Quality Objective Annual PM 10 Concentration Kerbside % Façade % National Air Quality Objective Number Days PM 10 > 50 µg/m³ Kerbside % Façade % National Air Quality Objective Table 5-7 Predicted Air Quality Whitehorse Street Without Development 2009 With Development 2009 Difference Whitehorse Street Predicted Environmental Concentration (µg/m³) (µg/m³) (%) Annual NO 2 Concentration Kerbside % Façade % National Air Quality Objective Annual PM 10 Concentration Kerbside % Façade % National Air Quality Objective Number Days PM 10 > 50 µg/m³ Kerbside % Façade % National Air Quality Objective 35 35

18 Hertfordshire County Council Table 5-8 Predicted Air Quality Clothall Road Without Development 2009 With Development 2009 Difference Clothall Road Predicted Environmental Concentration (µg/m³) (µg/m³) (%) Annual NO 2 Concentration Kerbside % Façade % National Air Quality Objective Annual PM 10 Concentration Kerbside % Façade % National Air Quality Objective Number Days PM 10 > 50 µg/m³ Kerbside % Façade % National Air Quality Objective NO 2 Predicted Impacts The magnitude of change for NO 2 is Very Small for South Road, Whitehorse Street and Clothall Road. Whitehorse Street is within the soon to be declared AQMA and therefore this change is classed as a slight impact. South Road and Clothall Road are predicted to be well below the standard with the scheme and therefore the change is classed as a negligible impact. PM 10 Predicted Impacts The magnitude of change for PM 10 is Extremely Small for both South Road and Whitehorse Street. This change is classed as a negligible impact. The magnitude of change for PM 10 is Very Small for Clothall Road. This change is classed as a negligible impact. 5.3 Mitigation The air quality at Site 2A and Site 2B are well below the air quality objectives and therefore suitable for residential use without any mitigation measures. The predicted change in NO 2 and PM 10 levels due to the development traffic on the local network is very small. No mitigation measures are proposed.

19 Hertfordshire County Council CONCLUSIONS Baseline predictions at the development sites show that NO 2 and PM 10 levels are well below the National Air Quality Objectives. The development traffic associated with Site 2A and Site 2B has been reviewed and no significant increase of traffic will impact onto the existing traffic network. The impact has been evaluated to be as slight to negligible. The cumulative impact associated with all four sites potentially being in operation has been evaluated to be slight to negligible.

20 Drawing Geodetic Information British National Grid Transverse Mercator False Easting = 400,000m False Northing = -100,000m Central Meridian = -2 o Scale Factor = Latitude Of Origin = 49 o Project Baldock Date JULY 2008 Scale A4 Drawing No. Figure LOC.001.Rev2 TREENWOOD HOUSE ROWDEN LANE BRADFORD ON AVON WILTSHIRE BA15 2AU T: F:

21 Drawing Geodetic Information British National Grid Transverse Mercator False Easting = 400,000m False Northing = -100,000m Central Meridian = -2 o Scale Factor = Latitude Of Origin = 49 o Project Baldock Date JULY 2008 Scale A4 Drawing No. Figure LOC.002.Rev2 TREENWOOD HOUSE ROWDEN LANE BRADFORD ON AVON WILTSHIRE BA15 2AU T: F:

22 Drawing Geodetic Information British National Grid Transverse Mercator False Easting = 400,000m False Northing = -100,000m Central Meridian = -2 o Scale Factor = Latitude Of Origin = 49 o Project Baldock Date APRIL 2008 Scale A4 Drawing No. Figure LOC.003.Rev0 TREENWOOD HOUSE ROWDEN LANE BRADFORD ON AVON WILTSHIRE BA15 2AU T: F:

23 Hertfordshire County Council APPENDIX A Air Quality Standards and Objectives The UK Air Quality Strategy A summary of the current air quality objectives for the seven pollutants detailed in the Air Quality Regulations 2007 for the purpose of Local Air Quality Management is provided below: A summary is also provided for air quality objectives for particulate matter, nitrogen oxides and sulphur dioxide as detailed in the Air Quality Strategy Air Quality Objectives currently included in the Air Quality Regulations 2007 Pollutant Applies to Concentration Measured as Target date Benzene (C 6 H 6 ) England & Wales 5 µg/m 3 Annual mean ,3-Butadiene All UK 2.25 µg/m 3 Running annual mean Should already be achieved Carbon (CO) monoxide All UK 10 mg/m 3 Maximum daily running 8 hour mean Should already be achieved Lead (Pb) All UK 0.5 µg/m 3 Annual mean Should already be achieved Nitrogen Dioxide (NO 2 ) Sulphur dioxide (SO 2 ) Particulate Matter All UK 200 µg/m 3 1 hour mean All UK 40 µg/m 3 Annual mean All UK 350 µg/m 3 1 hour mean Should already be achieved All UK 125 µg/m 3 24 hour mean Should already be achieved All UK 40 µg/m 3 Annual mean Should already be achieved (PM 10 ) (gravimetric) All UK 50 µg/m 3 24 hour mean Should already be achieved Particulate Matter All UK 15% cut (target) Annual mean (PM 2.5 ) England & Wales 25 µg/m 3 (target) Annual mean 2020

24 Hertfordshire County Council APPENDIX B AIR QUALITY SIGNIFICANCE CRITERIA Tables AQ-1 and AQ-2 summarise the significance criterion specific to the assessment of air quality as taken from: NSCA (2006) Development Control: Planning for Air Quality: Update. Appendix 3: Descriptors for Impact Magnitude and Impact Significance in Air Quality Assessments. Table AQ-1 Criteria for Changes Magnitude of Change Annual Mean NO 2 / PM 10 Days PM 10 > 50 µg/m 3 Very Large +/- >25% +/- >25 Days Large +/ % +/ Days Medium +/ % +/ Days Small +/- 5-10% +/ Days Very Small +/- 1-5% +/- 1-5 Days Extremely Small +/- <1% +/- <1 Days Table AQ-2 Criteria for Impact Significance Magnitude of Change Extremely Small Very Small Small Medium Large Very Large Above Standard without Scheme Slight Slight Substantial Substantial Very Substantial Very Substantial Below Standard without Scheme. Above with Scheme Slight Moderate Substantial Substantial Very Substantial Very Substantial Below Standard without Scheme, but not well below Negligible Slight Slight Moderate Moderate Substantial Well below standard with scheme Negligible Negligible Slight Slight Slight Moderate

25 Hertfordshire County Council APPENDIX C BACKGROUND POLLUTANT CONCENTRATIONS Tables AQ-1 and AQ-2 summarise the background pollutant concentrations utilised in the DMRB model predictions. Site Table AQ-1 Background Pollutant Concentrations Grid Reference NO X µg/m³ Annual Mean NO 2 µg/m³ Annual Mean PM 10 µg/m³ Annual Mean Site , Location Whitehorse Street Table AQ-2 Background Pollutant Concentrations Grid Reference NO X µg/m³ Annual Mean NO 2 µg/m³ Annual Mean PM 10 µg/m³ Annual Mean , Clothall Road , South Road ,