2015 Updating and Screening Assessment for Wiltshire Council

In fulfillment of Part IV of the Environment Act 1995 Local Air Quality Management

May 2015

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Local Authority Peter Nobes Officer

Department Public protection County hall, Bythesea Road, Trowbridge. Address BA14 8JN Telephone 01380 826320 e-mail [email protected]

Report Reference WC/USA2015 number Date May 2015

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Executive Summary

This document summarises the current situation relating to the quality of the air in Wiltshire. The report has been completed by the Environmental Protection Team.

The document summarises all the air quality monitoring carried out by the council across the county of Wiltshire.

The report has concluded the following:

• Monitoring data has indicated exceedences of the NO2 annual mean objective in the Salisbury AQMAs; therefore the AQMAs are still justified.

• Monitoring data has indicated exceedences of the NO2 annual mean objective in the Bradford on Avon AQMA; therefore the AQMA is still justified.

• Monitoring data has indicated exceedences of the NO2 annual mean objective in the Westbury AQMA; therefore the AQMA is still justified.

• Monitoring data has indicated exceedences of the NO2 annual mean objective in the Calne AQMA; therefore the AQMA is still justified.

• Monitoring data has indicated exceedences of the NO2 annual mean objective in the Marlborough AQMA; therefore the AQMA is still justified.

• Monitoring data has indicated exceedences of the NO2 annual mean objective in the Devizes AQMA; therefore the AQMA is still justified.

• A Detailed Assessment for PM10 will have to be undertaken for a property in the vicinity of a Poultry Farm.

The general trend for air quality across the County is one of a slight improvement although many factors can influence air quality and no firm conclusions can be drawn.

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1 Introduction ...... 7 1.1 Description of Local Authority Area ...... 7 1.2 Purpose of Report ...... 7 1.3 Air Quality Objectives ...... 8 1.4 Summary of Previous Review and Assessments ...... 9 2 New Monitoring Data ...... 14 2.1. Summary of Monitoring Undertaken ...... 14 2.1.1 Automatic Monitoring Sites ...... 14 2.1.2 Non-Automatic Monitoring Sites ...... 18 2.2 Comparison of Monitoring Results with Air Quality Objectives ...... 37 2.2.1 Nitrogen Dioxide ...... 37

2.2.2 PM10 ...... 59 2.2.3 Sulphur Dioxide...... 64 2.2.4 Benzene ...... 64 2.2.5 Other pollutants monitored ...... 64 2.2.6 Summary of Compliance with AQS Objectives ...... 64 3 Road Traffic Sources ...... 65 3.1 Narrow Congested Streets with Residential Properties Close to the Kerb ...... 65 3.2 Busy Streets Where People May Spend 1-hour or More Close to Traffic ...... 65 3.3 Roads with a High Flow of Buses and/or HGVs...... 66 3.4 Junctions ...... 66 3.5 New Roads Constructed or Proposed Since the Last Round of Review and Assessment ...... 66 3.6 Roads with Significantly Changed Traffic Flows ...... 67 3.7 Bus and Coach Stations ...... 67 3.8 Airports ...... 68 3.9 Railways (Diesel and Steam Trains) ...... 68 3.9.1 Stationary Trains ...... 68 3.9.2 Moving Trains ...... 68 3.10 Ports (Shipping) ...... 69 4 Industrial Sources ...... 70 4.1 Industrial Installations ...... 70 4.1.1 New or Proposed Installations for which an Air Quality Assessment has been carried out...... 70 4.1.2 Existing Installations where Emissions have increased substantially or New Relevant Exposure has been introduced ...... 70 4.1.3 New or Significantly Changed Installations with No Previous Air Quality Assessment ...... 71

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4.2 Major Fuel (Petrol) Storage Depots ...... 71 4.1 Petrol Stations...... 71 4.2 Poultry Farms...... 72 5 Commercial and Domestic Sources ...... 74 5.1 Biomass Combustion – Individual Installations ...... 74 5.2 Biomass Combustion – Combined Impacts ...... 74 5.3 Domestic Solid-Fuel Burning ...... 74 6 Fugitive or Uncontrolled Sources ...... 75 7 Conclusions and Proposed Actions ...... 76 7.1 Conclusions from New Monitoring Data ...... 76 7.2 Conclusions from Assessment of Sources ...... 77 7.3 Proposed Actions ...... 78 Manual Calibration ...... 81

List of Tables Table 1.1 Air Quality Objectives included in Regulations for the purpose of LAQM in England Table 2.1 Details of automatic monitoring sites Table 2.2 Details of non-automatic monitoring sites Table 2.3 Results of automatic monitoring of nitrogen dioxide: Comparison with Annual Mean Objective Table 2.4 Results of automatic monitoring for nitrogen dioxide: Comparison with 1-hour mean Objective Table 2.5 Results of nitrogen dioxide diffusion tubes in 2014 Table 2.6 Results of nitrogen dioxide diffusion tubes (2010 to 2014)

Table 2.7 Results of automatic monitoring of PM10: Comparison with Annual Mean Objective

Table 2.8 Results of automatic monitoring of PM10: Comparison with 24-hour mean Objective Table 4.2 Poultry farms permitted by the Environment Agency in Wiltshire

List of Figures Figure 1 Map of AQMA boundaries - Salisbury Figure 2 Map of AQMA boundary – Bradford on Avon Figure 3 Map of AQMA boundary - Westbury Figure 4 Map of AQMA boundary - Marlborough Figure 5 Map of AQMA boundary - Calne Figure 6 Map of AQMA boundary - Devizes Figure 7 Automatic monitoring site, Salisbury (AM1) Figure 8 Automatic monitoring site, Bradford on Avon (AM2) Figure 9 Automatic monitoring site, Devizes (AM3) Figure 10 Automatic monitoring site, Calne (AM4) Figure 11 Map of diffusion tube locations in Salisbury Figure 12 Map of diffusion tube locations in Trowbridge Figure 13 Map of diffusion tube locations in Bradford on Avon Figure 14 Map of diffusion tube locations in Devizes Figure 15 Map of diffusion tube locations in Marlborough Figure 16 Map of diffusion tube locations in Calne Figure 17 Map of diffusion tube locations in Chippenham

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Figure 18 Map of diffusion tube locations in Westbury Figure 19 Map of diffusion tube locations in Wilton Figure 20 Trends in annual mean nitrogen dioxide concentrations measured at automatic monitoring sites (2006 – 2014) Figure 21 Trend graph for annual mean nitrogen dioxide concentrations at South Western Road and Minster Street, Salisbury Figure 22 Trend graph for annual mean nitrogen dioxide concentrations at Brown Street and Exeter Street, Salisbury Figure 23 Trend graph for annual mean nitrogen dioxide concentrations at Fisherton Sreet and London Road, Salisbury Figure 24 Trend graph for annual mean nitrogen dioxide concentrations at Castle Street and Winchester Street, Salisbury Figure 25 Trend graph for annual mean nitrogen dioxide concentrations at Masons Lane and Silver Street, Bradford on Avon Figure 26 Trend graph for annual mean nitrogen dioxide concentrations at Shanes Castle, Hillsborough and Chantry Court, Devizes Figure 27 Trend graph for annual mean nitrogen dioxide concentrations at London Road , Herd Street and Salisbury Road, Marlborough Figure 28 Trend graph for annual mean nitrogen dioxide concentrations at Haynes Road and Warminster Road, Westbury Figure 29 Trend graph for annual mean nitrogen dioxide concentrations at Queen Street and West Street, Wilton Figure 30 Trends for annual mean PM10 concentrations from automatic monitoring at Exeter St, Salisbury

Appendices Appendix A QA/QC data

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1 Introduction 1.1 Description of Local Authority Area

Wiltshire Council’s administrative area takes in the whole of the county of Wiltshire with the exception of Swindon, a unitary authority in its own right. The county is roughly rectangular, approximately 45 miles north/ south and 33 miles east/ west

The majority of the county is rural in nature, taking in the world heritage sites, Stonehenge and Avebury. Salisbury plain dominates the southern portion of the county and large tracts are utilised by the military for their manoeuvres. Much of the area enjoys the protection of special designations such as SSIs, scheduled ancient monuments and National Park.

The administrative headquarters of Wiltshire are situated in Trowbridge. There are many small settlements and towns across Wiltshire, the largest urban concentrations are in Salisbury, Devizes, Chippenham, Malmesbury, Melksham, Warminster and Westbury.

The main sources of pollutants of concern are road vehicles. Wiltshire has a number of market towns with narrow streets and comparatively tall buildings (3-4 stories) which in many cases are direct onto the street, giving rise to canyon effects that inhibit pollutant dispersal. Added to this we are a popular tourist destination which contributes to summer congestion and Wiltshire’s topography is not flat. This is a factor in some locations that fail to meet an objective as goods vehicles must stop/ start as they progress up hill.

1.2 Purpose of Report

This report fulfils the requirements of the Local Air Quality Management process as set out in Part IV of the Environment Act (1995), the Air Quality Strategy for England, Scotland, Wales and Northern Ireland 2007 and the relevant Policy and Technical Guidance documents. The LAQM process places an obligation on all local authorities to regularly review and assess air quality in their areas, and to determine whether or not the air quality objectives are likely to be achieved. Where exceedences are considered likely, the local authority must then declare an Air Quality Management

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Area (AQMA) and prepare an Air Quality Action Plan (AQAP) setting out the measures it intends to put in place in pursuit of the objectives.

The objective of this Updating and Screening Assessment is to identify any matters that have changed which may lead to risk of an air quality objective being exceeded. A checklist approach and screening tools are used to identify significant new sources or changes and whether there is a need for a Detailed Assessment. The USA report should provide an update of any outstanding information requested previously in Review and Assessment reports.

1.3 Air Quality Objectives

The air quality objectives applicable to LAQM in England are set out in the Air Quality (England) Regulations 2000 (SI 928), The Air Quality (England) (Amendment) Regulations 2002 (SI 3043), and are shown in Table 1.1. This table shows the objectives in units of microgrammes per cubic metre µg/m3 (milligrammes per cubic metre, mg/m3 for carbon monoxide) with the number of exceedences in each year that are permitted (where applicable).

Table 1.1 Air Quality Objectives included in Regulations for the purpose of LAQM in England Air Quality Objective Date to be Pollutant Concentration Measured as achieved by Running annual 16.25 µg/m3 31.12.2003 mean Benzene Running annual 5.00 µg/m3 31.12.2010 mean Running annual 1,3-Butadiene 2.25 µg/m3 31.12.2003 mean Running 8-hour Carbon monoxide 10.0 mg/m3 31.12.2003 mean 0.5 µg/m3 Annual mean 31.12.2004 Lead 0.25 µg/m3 Annual mean 31.12.2008 200 µg/m3 not to be exceeded more than 1-hour mean 31.12.2005 Nitrogen dioxide 18 times a year 40 µg/m3 Annual mean 31.12.2005

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50 µg/m3, not to be 31.12.2004 Particles (PM10) exceeded more than 24-hour mean (gravimetric) 35 times a year 40 µg/m3 Annual mean 31.12.2004 350 µg/m3, not to be exceeded more than 1-hour mean 31.12.2004 24 times a year 125 µg/m3, not to be Sulphur dioxide exceeded more than 24-hour mean 31.12.2004 3 times a year 266 µg/m3, not to be exceeded more than 15-minute mean 31.12.2005 35 times a year

1.4 Summary of Previous Review and Assessments

This section reports on the conclusion of rounds of the Review and Assessment process for Wiltshire Council. A summary of the reports produced, conclusions etc for the authorities that governed the County prior to the 1/4/2009 can be found in the 2014 Progress Report submitted to and approved by DEFRA, available via this link: http://www.wiltshireairquality.org.uk/reports

Wiltshire Council Report Date Conclusion Updating & Screening 2009 All AQMAs declared still stand and Detailed Assessment Assessment is underway for Wilton, Marlborough and Devizes for exceedences of

the annual average objective for NO2 Air Quality Action Plan 2009 DEFRA advised of progress with AQAP Progress Report implementation Progress Report 2010 No Detailed assessments required, however monitoring locations have been reviewed to cover areas where monitoring has not previously been undertaken. Detailed Assessment, 2010 An AQMA is required for exceedences of the

Shanes Castle, Devizes annual average objective for NO2 Detailed Assessment, 2010 An AQMA is not required for exceedences of

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Wilton the annual average objective for NO2 however monitoring will continue in the town Detailed Assessment, Herd 2010 An AQMA is required for exceedences of the

Street, Marlborough annual average objective for NO2

Progress Report 2011 Detailed assessment required for NO2 in Calne and Devizes Air Quality Strategy for 2011 Adopted by cabinet Wiltshire 2011 - 2015 Updating & Screening 2012 No further areas identified requiring Detailed Assessment 2012 Assessments. Detailed Assessment for June AQMA required for New Road and Curzon Calne 2012 Street Detailed Assessment for June AQMA needs to be extended to include The Devizes 2012 Nursery, Northgate Street, St James Place, Southgate roundabout. Further Assessment for Feb The AQMA is justified. DEFRA have accepted Marlborough 2013 this conclusion. Progress Report 2013 Detailed Assessments required for sites in Salisbury, Chippenham, Westbury, Bradford on Avon and Trowbridge. Detailed Assessment for May Detailed assessment produced to cover the 5 Wiltshire 2014 towns identified in the 2013 Progress Report. AQMA extension required for Wilton Road, Salisbury. Progress Report May All current AQMA’s are still valid, no 2014 requirement to progress to a detailed assessment as a consequence of the results reported.

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Figure 1 - Map of AQMA boundaries - Salisbury

Figure 2 - Map of AQMA boundary - Bradford on Avon

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Figure 3 - Map of AQMA boundary - Westbury

Figure 4 - Map of AQMA boundary – Marlborough

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Figure 5 – Map of AQMA boundary – Calne

Figure 6 – Map of AQMA boundary - Devizes

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2 New Monitoring Data 2.1. Summary of Monitoring Undertaken

2.1.1 Automatic Monitoring Sites

During 2014 Wiltshire Council employed 4 automatic air quality monitoring stations as described in Table 2.1. All information relating to quality control / quality assurance of our monitoring is set out in Appendix A

Set out below are a series of maps detailing the location of all Wiltshire Council’s continuous air quality monitoring sites.

Figure 7 – Automatic monitoring site, Salisbury (AM1)

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Figure 8 - Automatic monitoring site, Bradford on Avon (AM2)

Figure 9 - Automatic monitoring site, Devizes (AM3)

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Figure 10 - Automatic monitoring site, Calne (AM4)

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Table 2.1 Details of automatic monitoring sites Relevant exposure? Distance Does this (Y/N with to kerb of location Y OS Inlet Site X OS grid Pollutants In Monitoring distance nearest represent Site name Site type grid height ID reference monitored AQMA? technique (m) from road (m) worst- reference (m) site to (N/A if not case relevant applicable) exposure? exposure) Exeter Chemiluminesence. AM1 Street, Roadside 414547 129575 2 NOx, PM10 Yes Yes 2.5 Yes Beta Attenuation. Salisbury Masons Lane, Chemiluminesence AM2 Roadside 382533 161115 3 NOx,, PM10 Yes No 1.6 Yes Bradford On Beta Attenuation Avon Sidmouth Chemiluminesence. Street, Roadside 400765 161458 2 NOx, PM10 Yes Yes 2.5 Yes AM3 Beta Attenuation. Devizes Woodlands Social AM4 Roadside 399880 170717 3 NOx Yes Chemiluminesence Yes 0.5 Yes Club, Calne

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2.1.2 Non-Automatic Monitoring Sites

The only non automatic monitoring of Air Quality carried out by Wiltshire Council is for Nitrogen Dioxide utilising diffusion tubes at a total of 72 sites across the county. Table 2.2 below details the locations of all the sites used and includes a reference number for each site located in 2014 which are shown in the maps set out in Figures 11 - 19 below.

Please note that the site reference number prefix P14 is not shown on the location maps, just the final reference number for each tube site.

Maps showing the locations of all the passive diffusion tube monitoring sites in Wiltshire.

Figure 11 – Salisbury (including AQMA’s)

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Figure 12 – Trowbridge

Figure 13 – Bradford on Avon (including AQMA)

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Figure 14 – Devizes (including AQMA)

Figure 15 – Marlborough (including AQMA)

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Figure 16 – Calne (including AQMA)

Figure 17 – Chippenham

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Figure 18 – Westbury (including AQMA)

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Table 2.2 Details of non-automatic monitoring sites

Salisbury diffusion tubes Relevant Is exposure? Distance Does this monitoring (Y/N with to kerb of location Site co-located distance Site X OS grid Y OS grid Pollutants In nearest represent Site ID Site type height with a (m) from name reference reference monitored AQMA? road (m) worst- (m) continuous monitoring (N/A if not case analyser site to applicable) exposure? (Y/N) relevant exposure) 74 London P14/30 Roadside 415105 130641 2.2 NO2 Y N Y (0) 8.4 Y Road 6 Castle P14/92 Roadside 414362 130105 2.6 NO Y N Y(1) 1.5 Y Street 2 93 Castle P14/37 Roadside 414400 130400 3 NO Y N Y (0) 1.8 Y Street 2 161 Castle P14/94 Roadside 414312 130651 2.7 NO Y N Y (0) 1.75 Y Street 2 1 High P14/32 Roadside 414306 129916 2.5 NO Y N N 3 Y Street 2 2 Minster P14/34 Kerbside 414373 129979 3 NO Y N Y (0) 1.5 Y Street 2

P14/39 Endless St Roadside 414500 130105 2.6 NO2 Y N Y(0) 2.9 Y

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P14/35 Winchester Roadside 414602 130054 2.75 NO2 Y N Y (1) 1.5 Y Street 100 Brown P14/36 Roadside 414635 129692 2.4 NO Y N Y (0) 2 Y Street 2 123 South

P14/38 Western Roadside 413828 130142 2.5 NO2 Y N Y (0) 1.5 Y Road 17

P14/44 Fisherton Roadside 414101 130025 2.8 NO2 Y N Y (0) 2 Y Street 88 Park P14/48 Background 414760 130567 2.5 NO Y N Y (2) 0.3 Y Street 2 17 Wilton P14/46 Roadside 413690 130362 2.7 NO Y N Y (0) 1.5 Y Road 2 225 Wilton P14/88 Roadside 412572 130673 2.7 NO N* N Y(0) 1.8 Y Road 2

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Relevant Is exposure? Distance Does this monitoring (Y/N with to kerb of location Site co-located distance Site X OS grid Y OS grid Pollutants In nearest represent Site ID Site type height with a (m) from name reference reference monitored AQMA? road (m) worst- (m) continuous monitoring (N/A if not case analyser site to applicable) exposure? (Y/N) relevant exposure) 31 Devizes P14/47 Roadside 413669 130503 2.6 NO Y N Y (1.0) 0.5 Y Road 2 91 Exeter P14/49 Roadside 414550 129523 3 NO Y N Y (2.0) 0.4 Y Street 2 1 St Marks P14/40 Roadside 415040 130640 2.4 NO Y N Y (0) 4.1 Y Avenue 2 Parkview,

P14/90 107 Wilton Roadside 413038 130526 2 NO2 N N Y(0) 5 N Rd HSBC P14/87 Roadside 413364 130016 2.7 NO Y N Y(3) 2.6 N Minster St 2

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Trowbridge diffusion tubes

Relevant Is exposure? Distance Does this monitoring (Y/N with to kerb of location Site co-located distance Site Site X OS grid Y OS grid Pollutants In nearest represent Site type height with a (m) from ID name reference reference monitored AQMA? road (m) worst- (m) continuous monitoring (N/A if not case analyser site to applicable) exposure? (Y/N) relevant exposure) 26 P14/59 Kerbside 385232 157545 2.25 NO N N Y(1) 0.1 Y Newtown 2 Bradford Rd, P14/62 Roadside 384977 157883 2 NO N N Y(5) 3 N Medical 2 Centre Rosset Urban P14/63 384341 157806 2 NO N N Y(10) 1 N Gardens Background 2 Wingfield P14/60 Roadside 384990 157706 2 NO N N Y(5) 1.5 Y Rd 2 Wingfield Rd P14/62 Roadside 384529 157507 2 NO N N N 1 N opposite 2 carehome

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Bradford on Avon diffusion tubes

Relevant Is exposure? Distance Does this monitoring (Y/N with to kerb of location Site co-located distance Site Site X OS grid Y OS grid Pollutants In nearest represent Site ID height with a (m) from name type reference reference monitored AQMA? road (m) worst- (m) continuous monitoring (N/A if not case analyser site to applicable) exposure? (Y/N) relevant exposure) 9 Masons P14/0 Roadside 382590 161146 2.5 NO Y N Y (1) 1.35 Y Lane 2 16 New P14/2 Roadside 382953 161306 3.0 NO N N Y (12) 1.8 N Road 2 12 Market P14/76 Kerbside 382586 161054 2.4 NO Y N Y (1) 0.95 Y Street 2 7 Bath P14/68 Roadside 382596 161446 2.5 NO N N Y(1) 2.4 Y Road 2 8 Mount P14/69 Kerbside 382769 161307 2.5 NO N N Y(2) 0.9 Y Pleasant 2 21 Woolley

P14/71 Street Roadside 382771 161030 2.4 NO2 N N Y(2) 2.1 Y (B&B)

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Relevant Is exposure? Distance Does this monitoring (Y/N with to kerb of location Site co-located distance Site Site X OS grid Y OS grid Pollutants In nearest represent Site ID height with a (m) from name type reference reference monitored AQMA? road (m) worst- (m) continuous monitoring (N/A if not case analyser site to applicable) exposure? (Y/N) relevant exposure) Rear of Tillions, P14/1 Kerbside 382660 160990 2 NO Y N Y (1) 0.5 Y Silver 2 Street Skew Cottage, P14/73 Roadside 382520 160276 2.6 NO N N Y(1) 1.6 Y 40 Frome 2 Road 224

P14/67 Winsley Roadside 382360 161280 2.5 NO2 N N Y(1) 1.4 Y Road

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Devizes diffusion tubes

Relevant Is exposure? Distance Does this monitoring (Y/N with to kerb of location Site co-located Site X OS grid Y OS grid Pollutants In distance nearest represent Site ID Site name height with a type reference reference monitored AQMA? (m) from road (m) worst- (m) continuous site to (N/A if not case analyser relevant applicable) exposure? (Y/N) exposure) Hillsborough, P14/10 Roadside 399715 161702 2.4 NO2 N N Y (1) 4 Y Bath Road

P14/14 5 The Nursery Roadside 399924 161729 2.75 NO2 Y N Y((1.5) 2 Y

P14/13 Shanes Castle Roadside 400762 161635 2 NO2 Y N Y (1) 1.1 Y Opp Wadworths, P14/12 Roadside 400210 161635 2.8 NO Y N Y(8) 1.7 Y 41 Northgate St 2 Chantry Ct, P14/16 Roadside 400635 161554 2.5 NO Y N Y (3.2) 1.8 Y New Park Street 2 Sudweeks Ct, P14/17 Roadside 400362 161673 2.5 NO Y N Y (2) 2.5 Y New Park Street 2 105 St James P14/15 Roadside 400807 161388 2.6 NO Y N Y(1) 2.3 Y Place 2

P14/21 12 Southgate St Roadside 400634 160982 2.75 NO2 Y N Y (1.5) 1.8 Y Mirfield, London P14/84 Roadside 401120 161559 2 NO Y N Y(0.2) 3 Y Road 2

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Marlborough diffusion tubes

Is Relevant Distance Does this monitoring exposure? to kerb of location Site co-located (Y/N with Site Site X OS grid Y OS grid Pollutants In nearest represent Site name height with a dist (m) ID type reference reference monitored AQMA? road (m) worst- (m) continuous from site to (N/A if not case analyser relevant applicable) exposure? (Y/N) exposure) 6 Herd P14/22 Roadside 418942 169383 2 NO2 Y N Y (1) 1.8 Y Street 27 Herd P14/25 Roadside 418910 169448 2 NO Y N Y (1) 1.4 Y Street 2 116 High P14/24 Roadside 418725 169048 2.4 NO Y N Y (5) 1.8 Y Street 2 6 Barn P14/26 Roadside 419047 169226 2.2 NO Y N Y (1) 1.6 Y Street 2 13 Salisbury P14/27 Roadside 419300 168762 2.4 NO Y N Y (2.5) 1.8 Y Road 2 War

P14/28 Memorial, Roadside 419248 168981 2.5 NO2 Y N Y (4) 1.1 Y London Rd 115 London P14/29 Roadside 419153 169081 2.5 NO Y N Y (1) 1.5 Y Road 2

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Calne diffusion tubes

Relevant Is exposure? Distance Does this monitoring (Y/N with to kerb of location Site co-located distance Site Site X OS grid Y OS grid Pollutants In nearest represent Site name height with a (m) from ID type reference reference monitored AQMA? road (m) worst- (m) continuous monitoring (N/A if not case analyser site to applicable) exposure? (Y/N) relevant exposure) Chilvester,

P14/4 1 Oxford Roadside 399728 171206 2.2 NO2 Y N N 2.25 Y Road 18 Curzon P14/3 Roadside 399516 171184 2 NO Y N Y (1.3) 2.05 Y Street 2 57 Curzon P14/8 Roadside 399658 171164 2.5 NO Y N Y (1) 1.8 Y Street 2 34 New P14/5 Roadside 399872 170738 2.5 NO Y N Y (1.8) 1.15 Y Road 2 30 London P14/6 Roadside 399998 170569 2.5 NO N N Y (1.5) 2.1 Y Road 2 White Hart, P14/80 Roadside 399917 170700 2.8 NO Y N N 1.8 N The Green 2

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Chippenham diffusion tubes

Relevant Is exposure? Distance Does this monitoring (Y/N with to kerb of location Site co-located distance Site X OS grid Y OS grid Pollutants In nearest represent Site ID Site name height with a (m) from type reference reference monitored AQMA? road (m) worst- (m) continuous monitoring (N/A if not case analyser site to applicable) exposure? (Y/N) relevant exposure) Providence

P14/64 Terrace, Ivy Roadside 391776 173448 2.4 NO2 N N Y(2.5) 1.5 Y Lane Bridge

P14/65 Centre, Roadside 391725 173281 2.4 NO2 N N Y(6.8) 2.4 Y Bath Road Bath Road,

P14/66 Rowden Hill Roadside 391582 173093 2.5 NO2 N N Y(6.3) 2 Y Way

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Westbury diffusion tubes

P14/50 Warminster Roadside 387255 151087 2.5 NO2 Y N Y(4) 1.9 Y Road 76

P14/52 Warminster Roadside 387157 150901 2.2 NO2 Y N Y (1) 1.7 Y Road 41 Haynes P14/51 Roadside 387240 151164 2.1 NO Y N Y (1) 1.3 Y Road 2 23 West P14/57 Roadside 387269 151507 2.5 NO N N Y(1) 1.5 Y End 2

P14/56 12 Fore St Roadside 387369 151600 2.5 NO2 N N Y(1) 2 Y Primmers P14/58 Roadside 386470 151928 2.5 NO N N Y(2) 2 Y Place 2

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Wilton diffusion tubes

Salisbury Co-location diffusion tubes

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Devizes Co-location diffusion tubes

Bradford on Avon Co-location diffusion tubes

Relevant Is exposure? Distance Does this monitoring (Y/N with to kerb of location Site co-located distance Site X OS Grid Y OS Grid Pollutants In nearest represent Site ID Site Name height with a (m) from type reference reference monitored AQMA? road (m) worst- (m) continuous monitoring (N/A if not case analyser site to applicable) exposure? (Y/N) relevant exposure) Newtown P13/77- Corner, Roadside 382533 161115 3 NO2 Y Y N 3 Y 79 Masons Lane

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Calne Co-location diffusion tubes

Relevant Is exposure? Distance Does this monitoring (Y/N with to kerb of location Site co-located distance Site X OS Grid Y OS Grid Pollutants In nearest represent Site ID Site Name height with a (m) from type reference reference monitored AQMA? road (m) worst- (m) continuous monitoring (N/A if not case analyser site to applicable) exposure? (Y/N) relevant exposure) P/13 Woodlands Roadside 399880 170717 3 NO2 Yes Y Y 0.5 Y 81-83 Social Club

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2.2 Comparison of monitoring results with Air Quality Objectives

All automatic monitoring carried out within Wiltshire is now uploaded to a dedicated Air Quality website managed by Ricardo-AEA: http://www.wiltshireairquality.org.uk/

The website can be used to download data from any period and includes all relevant data from the start of 2014. Data is ratified by Ricardo-AEA prior to being uploaded.

2.2.1 Nitrogen dioxide

Automatic monitoring data

The automatic monitoring for NO2 located on Exeter Street in Salisbury (AM1) for 2014 reported an annual mean of 34.5ug/m3, below the relevant Air Quality Objective of 40µg/m3. No exceedences of the hourly objective of 200µg/m3 (not to be exceeded more than 18 times a year) were reported. Data capture for the period was good at 91% with data for the month of July not recorded due to equipment failure. The site is located within the existing Salisbury City AQMA

The automatic monitoring for NO2 located in Masons Lane, Bradford on Avon (AM2) was relocated during 2014 as permission to use the site at the Old Rectory was with withdrawn at the end of February. The site was relocated to the site shown in Figure 8 but could not be commissioned until the 18th June.

Data capture for the year from 18th June was good at 98% but overall data capture for the year is poor at 53%. The an annual mean reported for this monitoring period was 34.5µg/m3, below the relevant Air Quality Objective of 40µg/m3 and no exceedences of the hourly objective of 200µg/m3 were reported. The site is located within the existing Bradford on Avon AQMA

The automatic monitoring for NO2 located on Sidmouth Street, Devizes (AM3) for 2014 reported an annual mean of 38.2µg/m3, below the relevant Air Quality Objective

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of 40µg/m3 and no exceedences of the hourly objective of 200µg/m3 were noted. Data capture for the period was very good at 92.5%. The site is located within the existing Devizes AQMA.

The automatic monitoring for NO2 located on New Road, Calne (AM4) reported an annual mean of 33.5µg/m3, below the relevant Air Quality Objective of 40µg/m3 with no exceedences of the hourly objective of 200µg/m3. Data capture for the period was moderate at 75% with significant failures of the circuit board in January, March and May which resulted in no data being recorded. The site is located within the existing Calne AQMA.

In cases where data capture is below 75% of a calendar year the mean shall be annualised in accordance with the methodology in Box 3.2 of LAQM.TG(09), before being compared to annual mean objectives. .

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Table 2.3 Results of automatic monitoring of nitrogen dioxide: comparison with Annual Mean Objective Valid data Annual mean concentration µg/m3 capture for Valid data Within period of capture 2014 Site ID Site type AQMA? monitoring %a % b 2010* c 2011* c 2012* c 2013* c 2014 c AM1 Roadside Y - 91 42 36 39 47 34.5 AM2 Roadside Y 98 53 NA NA NA NA 34.5 AM3 Roadside Y - 92.5 NA 36 44 37 38.2 AM4 Roadside Y - 75 NA NA NA 33 33.5

3 In bold, exceedence of the NO2 annual mean AQS objective of 40µg/m a i.e. data capture for the monitoring period, in cases where monitoring was only carried out for part of the year. b i.e. data capture for the full calendar year (e.g. if monitoring was carried out for six months the maximum data capture for the full calendar year would be 50%). c Means should be “annualised” as in Box 3.2 of TG(09), if monitoring was not carried out for the full year.

*Annual mean concentrations for previous years are optional.

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Figure 20 - Trends in annual mean nitrogen dioxide concentrations measured at Automatic Monitoring Sites (2006 – 2014)

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Table 2.4 Results of automatic monitoring for nitrogen dioxide: comparison with 1-hour mean Objective Valid data Number of exceedences of hourly mean (200 µg/m3) capture for Valid data Within period of capture 2014 Site ID Site type AQMA? monitoring %a % b 2010* c 2011* c 2012* c 2013* c 2014 c AM1 Roadside Y - 91 0 0 0 0 0 AM2 Roadside Y 98 53 NA NA NA 0 0 AM3 Roadside Y - 92.5 NA 0 5 0 0 AM4 Roadside Y - 75 NA NA NA 0 0 3 In bold, exceedence of the NO2 hourly mean AQS objective (200µg/m – not to be exceeded more than 18 times per year) a i.e. data capture for the monitoring period, in cases where monitoring was only carried out for part of the year. b i.e. data capture for the full calendar year (e.g. if monitoring was carried out for six months the maximum data capture for the full calendar year would be 50%). c If the period of valid data is less than 90%, include the 99.8th percentile of hourly means in brackets *Number of exceedences for previous years are optional.

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Diffusion tube monitoring data

The nitrogen dioxide diffusion tubes used by Wiltshire Council in 2014 are supplied and analysed by Gradko Laboratories using 20% TEA in water. Gradko participate in the WASP Scheme and performed as ‘good’ in 16 out of 16 tube precision studies carried out in 2014. This information was taken from the summary report published on the LA Support Helpdesk. http://laqm.defra.gov.uk/diffusion-tubes/precision.html

Details of the Quality Assurance / Quality Control (QA/QC) for the diffusion tube results reported in this section are set out in Appendix A, QA/QC for diffusion tube data.

Passive diffusion tubes are not as accurate as real time monitoring, however they do give a good indication of what is happening with air quality. Wiltshire currently has 72 sites within the district to monitor for nitrogen dioxide.

A nitrogen dioxide passive diffusion tube is a clear plastic tube open at one end and at the closed end a mesh is impregnated with a pollutant absorbing chemical. The diffusion tube collects the pollutant during the exposure period and then is resealed and returned to a laboratory for analysis. Each tube is exposed for a month period. The laboratory then assesses the quantity of the pollutant absorbed by calculating the average ambient NO2 concentration over the exposure period.

Each tube is mounted on a lamp-post or similar structure ensuring that the open end is at the bottom to prevent rainwater collection. Monitoring locations are representative of relevant exposure (e.g. households, schools).

Co location and bias correction Wiltshire has co-location studies at all real time monitoring stations, the Exeter Street continuous site in Salisbury, Masons Lane in Bradford on Avon, Woodlands Social Club in Calne and Sidmouth Street in Devizes.

A bias correction factor of 0.91 for Gradko tubes processed using 20% TEA in water has been obtained from the national bias correction website on March 26th 2015.

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http://laqm.defra.gov.uk/bias-adjustment-factors/national-bias.html

Diffusion tube data

The diffusion tube monitoring results for 2014 presented below confirm that the AQMA’s already declared within Wiltshire are all still valid with a number of exceedences at monitoring sites located within existing AQMA’s or within an area recommended as part of an extension to an existing AQMA as a result of the Wiltshire Council 2014 detailed assessment.

Exceedences of the annual mean objective for Nitrogen Dioxide were recorded at the following sites outside of existing or planned AQMA’s:

• P14/65 - Bath Road, adjacent to the Bridge Centre, Chippenham • P14/66 - Bath Road, Rowden Hill, Chippenham

The levels reported for 2014 monitoring in this document are the same as those reported for 2013 in the 2014 Progress Report for Wiltshire Council.

Wiltshire Council has already considered the exceedences at these two sites in previous reporting (2014 Progress Report for P14/66 and the 2014 Detailed Assessment for P14/65) and has concluded that further assessment is not required to investigate a potential exceedence of the annual mean AQO for NO2.

It is, however, recommended that both sites are moved to the façade of the nearest relevant exposure in order to establish the concentrations directly rather than theoretically.

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Table 2.5 Results of nitrogen dioxide diffusion tubes in 2014 Salisbury diffusion tubes Full calendar year data 2014 annual mean In Triplicate or co- 3 Site ID Site name Site type capture 2014 (Number of concentration (µg/m ) - bias AQMA? located tube? b Months) adjustment factor = 0.91 P14/30 74 London Road Roadside Y N 12 41

P14/92 6 Castle Street Roadside Y N 12 33 P14/37 93 Castle Street Roadside Y N 12 33 P14/94 161 Castle Street Roadside Y N 11 35 P14/32 1 High Street Roadside Y N 12 30 P14/34 2 Minster Street Kerbside Y N 11 37 P14/39 Endless St Roadside Y N 12 33 P14/35 16 Winchester Street Roadside Y N 12 33 P14/36 100 Brown Street Roadside Y N 12 33 P14/38 123 South Western Road Roadside Y N 12 50 P14/44 17 Fisherton Street Roadside Y N 12 34 P14/48 88 Park Street Background Y N 12 20 P14/46 17 Wilton Road Roadside Y N 12 56 P14/88 225 Wilton Road Roadside N* N 12 44 P14/47 31 Devizes Road Roadside Y N 12 40 P14/49 91 Exeter Street Roadside Y N 12 41 P14/40 1 St Marks Avenue Roadside Y N 12 31 P14/90 Parkview, 107 Wilton Road Roadside N N 12 36 P14/87 HSBC Minster St Roadside Y N 12 35 P14/41 Exeter Street Roadside Y Y 12 35

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Full calendar year data 2014 annual mean In Triplicate or co- 3 Site ID Site name Site type capture 2014 (Number of concentration (µg/m ) - bias AQMA? located tube? b Months) adjustment factor = 0.91 P14/42 Exeter Street Roadside Y Y 12 34 P14/43 Exeter Street Roadside Y Y 12 34 * In location recommended for AQMA following Wiltshire Council 2013 detailed assessment

Trowbridge diffusion tubes Full calendar year data 2014 annual mean In Triplicate or co- 3 Site ID Site name Site type capture 2014 (Number of concentration (µg/m ) - bias AQMA? located tube? b Months) adjustment factor = 0.91 P14/59 26 Newtown Kerbside N N 12 38 P14/61 Bradford Road Medical Centre Roadside N N 12 20 P14/63 Rosset Gardens Urban Bg N N 12 12 P14/60 Wingfield Road Roadside N N 12 22 P14/62 Wingfield Road opposite care home Roadside N N 12 24

Bradford on Avon diffusion tubes Full calendar year data 2014 annual mean In Triplicate or co- 3 Site ID Site name Site type capture 2014 (Number of concentration (µg/m ) - bias AQMA? located tube? b Months) adjustment factor = 0.91 P14/0 9 Masons Lane Roadside Y N 12 57 P14/76 12 Market Street Kerbside Y N 12 49 P14/68 7 Bath Road Roadside N N 12 39 P14/69 8 Mount Pleasant Kerbside N N 12 34 P14/71 21 Woolley Street (B&B) Roadside N N 10 29 P14/1 Rear of Tillions, Silver Street Kerbside Y N 12 35

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Full calendar year data 2014 annual mean In Triplicate or co- 3 Site ID Site name Site type capture 2014 (Number of concentration (µg/m ) - bias AQMA? located tube? b Months) adjustment factor = 0.91 P14/73 Skew Cottage, 40 Frome Road Roadside N N 12 37 P14/67 224 Winsley Road Roadside N N 12 32 P14/77 Masons Lane co-location Roadside Y Y 12 30 P14/78 Masons Lane co-location Roadside Y Y 12 30 P14/79 Masons Lane co-location Roadside Y Y 12 29

Devizes diffusion tubes Full calendar year data 2014 annual mean In Triplicate or co- capture 2014 (Number of concentration (µg/m3) - Site ID Site name Site type AQMA? located tube? Months) bias adjustment factor = 0.91 b P14/10 Hillsborough, Bath Road Roadside N N 12 32 P14/14 5 The Nursery Roadside Y N 12 41 P14/13 Shanes Castle Roadside Y N 12 41 P14/12 Opposite Wadworths, 41 Northgate Street Roadside Y N 11 44 P14/16 Chantry Court, New Park Street Roadside Y N 12 39 P14/17 Sudweeks Court, New Park Street Roadside Y N 12 28 P14/15 105 St James Place Roadside Y N 11 41 P14/21 12 Southgate Street Roadside Y N 12 38 P14/18 Sidmouth Street Roadside Y Y 12 36 P14/19 Sidmouth Street Roadside Y Y 12 38 P14/20 Sidmouth Street Roadside Y Y 12 39 P14/84 Mirfield, London Road Roadside Y N 12 26

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Marlborough diffusion tubes Full calendar year data capture 2014 annual mean In Triplicate or co- 3 Site ID Site name Site type 2014 (Number of Months) concentration (µg/m ) - bias AQMA? located tube? b adjustment factor = 0.91 P14/22 6 Herd Street Roadside Y N 12 54 P14/25 27 Herd Street Roadside Y N 12 47 P14/26 6 Barn Street Roadside Y N 12 44 P14/27 13 Salisbury Road Roadside Y N 12 41 P14/28 War Memorial, London Road Roadside Y N 12 33 P14/29 115 London Road Roadside Y N 12 41

Calne diffusion tubes Full calendar year data 2014 annual mean In Triplicate or co-located 3 Site ID Site name Site type capture 2014 (Number of concentration (µg/m ) - bias AQMA? tube? b Months) adjustment factor = 0.91 P14/4 Chilvester Shop, 1 Oxford Road Roadside Y N 12 39 P14/3 18 Curzon Street Roadside Y N 12 43 P14/8 57 Curzon Street Roadside Y N 12 32 P14/5 King George, 34 New Road Roadside Y N 12 54 P14/6 30 London Road Roadside N N 12 32 P14/70 White Hart Hotel, The Green Roadside Y N 12 39 P14/81 Woodlands Social Club Roadside Y Y 12 35 P14/82 Woodlands Social Club Roadside Y Y 12 35 P14/83 Woodlands Social Club Roadside Y Y 11 32

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Chippenham diffusion tubes Full calendar year data 2014 annual mean In Triplicate or co-located 3 Site ID Site name Site type capture 2014 (Number of concentration (µg/m ) - bias AQMA? tube? b Months) adjustment factor = 0.91 P14/64 Providence Terrace, Ivy Lane Roadside N N 12 29 P14/65 Bridge Centre, Bath Road Roadside N N 11 47 P14/66 Bath Road, Rowden Hill Roadside N N 12 41

Westbury diffusion tubes Full calendar year data 2014 annual mean In Triplicate or co-located 3 Site ID Site name Site type capture 2014 (Number of concentration (µg/m ) - bias AQMA? tube? b Months) adjustment factor = 0.91 P14/50 71 Warminster Road Roadside Y N 12 45 P14/52 76 Warminster Road lamppost Roadside Y N 12 32 P14/51 41 Haynes Road Roadside Y N 12 37 P14/57 23 West End Roadside N N 12 33 P14/56 12 Fore Street Roadside N N 12 37 P14/58 Primmers Place Roadside N N 12 26

Wilton diffusion tubes Full calendar year data 2014 annual mean In Triplicate or co-located 3 Site ID Site name Site type capture 2014 (Number of concentration (µg/m ) - bias AQMA? tube? b Months) adjustment factor = 0.91 P14/54 1 Queen Street Roadside N N 12 34 P14/55 12 West Street Roadside N N 11 24

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3 In bold, exceedence of the NO2 annual mean AQS objective of 40µg/m

3 Underlined, annual mean > 60µg/m , indicating a potential exceedence of the NO2 hourly mean AQS objective b If an exceedence is measured at a monitoring site not representative of public exposure, NO2 concentration at the nearest relevant exposure should be estimated based on the “NO2 fall-off with distance” calculator (http://laqm.defra.gov.uk/tools-monitoring-data/no2- falloff.html), and results should be discussed in a specific section. The procedure is also explained in Box 2.3 of Technical Guidance LAQM.TG(09) (http://laqm.defra.gov.uk/technical-guidance/index.html?d=page=30).

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Table 2.6 Results of nitrogen dioxide diffusion tubes (2010 to 2014) Annual mean concentration (µg/m3) - adjusted for bias a Within Site ID Site name Site type 2010 (bias 2011 (bias 2012 (bias 2013 (bias 2014 (bias AQMA? adjustment adjustment adjustment adjustment adjustment factor = 0.85) factor = 0.83) factor = 0.96) factor = 0.95) factor = 0.91) Salisbury P14/30 74 London Road Roadside Y 44 45 40 40 41 P14/92 6 Castle St Roadside Y - - - - 33 P14/37 93 Castle Street Roadside Y 42 38 35 35 33 P14/94 161 Castle Street Roadside Y - - 37 35 35 P14/32 1 High Street Roadside Y 41 36 30 32 30 P14/34 2 Minster Street Kerbside Y 54 47 40 42 37 P14/35 16 Winchester Street Kerbside Y 39 38 32 33 33 P14/36 100 Brown Street Roadside Y 41 39 36 33 33 P14/38 123 South Western Road Kerbside Y 44 49 43 45 50 P14/44 17 Fisherton Street Roadside Y 42 40 39 36 34 P14/48 88 Park Street Background Y 27 23 20 21 20 P14/46 17 Wilton Road Roadside Y 63 64 62 62 56 P14/88 225 Wilton Road Roadside N* - - 47 46 44 P14/47 31 Devizes Road Roadside N 41 44 42 44 40 P14/49 91 Exeter Street Roadside Y - - 39 42 41 P14/40 1 St Marks Avenue Roadside Y 33 34 32 31 31 P14/87 HSBC Minster Street Roadside Y - - 34 36 35 P14/90 Parkview, 107 Wilton Road Roadside N - - - 36 36 P14 Endless St Roadside N - - - - 33 /39

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Annual mean concentration (µg/m3) - adjusted for bias a Within Site ID Site name Site type 2010 (bias 2011 (bias 2012 (bias 2013 (bias 2014 (bias AQMA? adjustment adjustment adjustment adjustment adjustment factor = 0.85) factor = 0.83) factor = 0.96) factor = 0.95) factor = 0.91) Trowbridge P14/58 26 Newtown Kerbside N - - 40 37 38 P14/61 Bradford Road Medical Centre Roadside N - - - 22 20 P14/63 Rosset Gardens Roadside N - - - 13 12 P14/60 Wingfield Road Roadside N - - - 24 22 P14/62 Wingfield Road opposite carehome Roadside N - - - 20 24 Bradford on Avon P14/0 9 Masons Lane Roadside Y 70 74 71 76 57 P14/76 12 Market Street Kerbside Y 40 35 52 54 49 P14/68 7 Bath Road Roadside N - - 42 37 39 P14/69 8 Mount Pleasant Kerbside N - - 37 34 34 P14/71 21 Woolley Street (B&B) Roadside N - - 29 28 29 P14/1 Rear of Tillions, Silver Street Kerbside Y 38 36 37 32 35 P14/73 Skew Cottage, 40 Frome Road Roadside N - - 37 37 37 P14/67 224 Winsley Road Roadside N - - 35 35 32 Devizes P14/10 Hillsborough, Bath Road Roadside N 35 33 33 32 32 P14/14 5 The Nursery Roadside Y 47 47 42 45 42 P14/13 Shanes Castle Roadside Y 46 46 47 46 41 Opposite Wadworths, P14/12 Roadside Y 41 Northgate Street 45 48 44 43 44

P14/16 Chantry Court, New Park Street Roadside Y 44 41 40 41 39 P14/17 Sudweeks Court, New Park Street Roadside Y - 24 25 28 28

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Annual mean concentration (µg/m3) - adjusted for bias a Within Site ID Site name Site type 2010 (bias 2011 (bias 2012 (bias 2013 (bias 2014 (bias AQMA? adjustment adjustment adjustment adjustment adjustment factor = 0.85) factor = 0.83) factor = 0.96) factor = 0.95) factor = 0.91) P14/15 105 St James Place Roadside Y - - 41 42 41 P14/21 12 Southgate Street Roadside Y - - 41 37 38 P14/84 Mirfield, London Road Roadside Y - - - 27 26 Marlborough P14/22 6 Herd Street Roadside Y 52 59 63 64 54 P14/25 27 Herd Street Roadside Y 47 47 44 50 47 P14/26 6 Barn Street Roadside Y - 44 42 47 44 P14/27 13 Salisbury Road Roadside Y 41 43 44 43 41 P14/28 War Memorial, London Road Roadside Y - 33 34 36 33 P14/29 115 London Road Roadside Y - 47 42 44 41 Calne P14/4 Chilvester Shop, 1 Oxford Road Roadside Y - - 42 42 39 P14/3 18 Curzon Street Roadside Y 50 43 45 47 43 P14/8 57 Curzon Street Roadside Y - 29 31 35 32 P14/5 King George, 34 New Road Roadside Y 60 54 59 60 54 P14/6 30 London Road Roadside N - 32 35 38 32 P14/70 White Hart Hotel, The Green Roadside Y - - 41 40 39 P14/81 Woodlands Social Club Roadside Y - - - 35 35 P14/82 Woodlands Social Club Roadside Y - - - 35 35 P14/83 Woodlands Social Club Roadside Y - - - 36 33 Chippenham P14/64 Providence Terrace, Ivy Lane Roadside N - - 31 32 29 P14/65 Bridge Centre, Bath Road Roadside N - - 47 47 47

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3 In bold, exceedence of the NO2 annual mean AQS objective of 40µg/m

3 Underlined, annual mean > 60µg/m , indicating a potential exceedence of the NO2 hourly mean AQS objective

a Means should be “annualised” as in Box 3.2 of TG(09) (http://laqm.defra.gov.uk/technical-guidance/index.html?d=page=38), if full calendar year data capture is less than 75%

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2.4 Trends in annual mean nitrogen dioxide concentrations measured at diffusion tube monitoring Sites

Figure 21 – Trend graph for annual mean nitrogen dioxide concentrations at South Western Road (P14/38) and Minster Street (P14/34), Salisbury

Figure 22 – Trend graph for annual mean nitrogen dioxide concentrations at Brown Street (P14/36) and Exeter Street (P14/49), Salisbury

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Figure 23 – Trend graph for annual mean nitrogen dioxide concentrations at Fisherton Street (P14/44) and 74 London Road (P14/30), Salisbury

Figure 24 – Trend graph for annual mean nitrogen dioxide concentrations at 93 Castle Street (P14/37) and Winchester Street (P14/35), Salisbury

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Figure 25 – Trend graph for annual mean nitrogen dioxide concentrations at Masons Lane (P14/0) and Silver Street (P14/1), Bradford on Avon.

Figure 26 – Trend graph for annual mean nitrogen dioxide concentrations at Shanes Castle (P14/13), Hillsborough (P14/10) and Chantry Court (P14/16), Devizes.

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Figure 27 – Trend graph for annual mean nitrogen dioxide concentrations at 115 London Road (P14/29), 6 Herd St (P14/22) and 13 Salisbury Road (P14/27), Marlborough.

Figure 28 – Trend graph for annual mean nitrogen dioxide concentrations at Haynes Road (P14/51) and 76 Warminster Road (P14/52), Westbury

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Figure 29 – Trend graph for annual mean nitrogen dioxide concentrations at 1 Queen Street (P14/54) and 12 West Street (P14/55), Wilton.

The underlying trend for annual mean levels of nitrogen dioxide across the County is down with most sites showing an improvement in levels. This trend backs up the results from the real time monitoring.

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2.2.2 PM10

Wiltshire Council uses, BAM 1020 analysers in order to monitor for PM10. These automatically record’s dust concentrations with a built in data logging facility. All monitoring data is now uploaded to the Wiltshire Air Quality website, operated by AQA Ricardo as discussed in chapter 2.2.

The sampling head used on this equipment is specific to only allow particles less than 10 microns in size through to ensure that PM10 is accurately measured.

The analyser uses the principle of beta absorption to provide sample determination of mass concentration. An energy source of beta particles produces repeatable measurement characteristics. A glass fibre filter tape is used (30mm wide by 20 metres long) which allows for long periods of monitoring. A known amount of electron scattering and attenuation through a clean filter is compared with that of a dust sampled filter. The mass concentration is then calculated by the ratio of the number of detected beta particles passing through the filter and the sample volume.

The BAM 1020 PM10 analyser does not require fortnightly calibration checks as it automatically self-calibrates. Zero and span are applied at the beginning of every cycle - every 60 minutes. If the instrument fails to perform to its specification, an error is logged in the memory. The zero testing of the instrument is based on the unit’s ability to hold a constant output when measuring the blank filter paper. The span measurements are made by automatically inserting a reference membrane in the measurement path. The BAMs are serviced and calibrated every 6 months.

Automatic monitoring data

The automatic monitoring for PM10 located on Exeter Street in Salisbury (AM1) for 2014 reported an annual mean of 14ug/m3, below the relevant Air Quality Objective of 40µg/m3. 1 exceedence of the 24hour objective of 50µg/m3 (not to be exceeded more than 35 times a year) was reported. Data capture for the period was good at 92% with data for the month of July not recorded due to equipment failure. The site is located within the existing Salisbury City AQMA

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The automatic monitoring for PM10 located in Masons Lane, Bradford on Avon (AM2) was relocated during 2014 as permission to use the site at the Old Rectory was with withdrawn at the end of February. The site was relocated to the site shown in Figure 8 but could not be commissioned until the 18th June.

Data capture for the year from 18th June was good at 98% but overall data capture for the year is poor at 53%. The an annual mean reported for this monitoring period was 30.1µg/m3, below the relevant Air Quality Objective of 40µg/m3 with a total of 14 exceedences of the hourly objective of 50µg/m3 (not to be exceeded more than 35 times a year) reported. The site is located within the existing Bradford on Avon AQMA

The automatic monitoring for PM10 located on Sidmouth Street, Devizes (AM3) for 2014 reported an annual mean of 17µg/m3, below the relevant Air Quality Objective of 40µg/m3 and 3 exceedences of the hourly objective of 50µg/m3 (not to be exceeded more than 35 times a year) were noted.

Data capture for the period was very good at 92.5%. The site is located within the existing Devizes AQMA.

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Table 2.7 Results of automatic monitoring of PM10: comparison with Annual Mean Objective

Valid data Confirm Annual mean concentration (µg/m3) Valid data Within capture for gravimetric Site ID Site type capture c c c c c AQMA? monitoring b equivalent (Y 2010* 2011* 2012* 2013* 2014 a 2014 % period % or N/A) AM1 Roadside Y 92 NA 19 20 16 13 14 AM3 Roadside Y 89 NA - 19 17 15 17 AM2 Roadside Y NA - - - 28 30 3 In bold, exceedence of the PM10 annual mean AQS objective of 40µg/m a i.e. data capture for the monitoring period, in cases where monitoring was only carried out for part of the year b i.e. data capture for the full calendar year (e.g. if monitoring was carried out for six months the maximum data capture for the full calendar year would be 50%) c Means should be “annualised” as in Box 3.2 of TG(09) (http://laqm.defra.gov.uk/technical-guidance/index.html?d=page=38), if valid data capture is less than 75%

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Table 2.8 Results of automatic monitoring for PM10: Comparison with 24-hour mean Objective Number of exceedences of 24-hour Mean (50 µg/m3) Valid data Valid capture for data Confirm Site Within monitoring capture gravimetric ID Site type AQMA? Period %a 2014 %b equivalent 2010* c 2011* c 2012* c 2013* c 2014 c AM1 Roadside Y 92 Y 3 4 8 6 1 AM3 Roadside Y 89 Y 3 1 4 3 AM2 Roadside Y 94 51 Y 11 14 a i.e. data capture for the monitoring period, in cases where monitoring was only carried out for part of the year. b i.e. data capture for the full calendar year (e.g. if monitoring was carried out for six months the maximum data capture for the full calendar year would be 50%). c if data capture is less than 90%, include the 90th percentile of 24-hour means in brackets * Optional

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2.5 Trends in annual mean PM10 concentrations

Trend charts for annual mean PM10 results for the automatic monitoring sites where Wiltshire Council have monitored for at least the last 5 years are presented and discussed below.

Figure - 30 Trends for annual mean PM10 concentrations from automatic monitoring at Exeter St (AM1), Salisbury

The general 5 year tend for the automatic monitoring of annual mean concentration of PM10 particulates located in Exeter Street, Salisbury (AM1) is down although the 2014 annual mean level reported is slightly up on the 2013 reported mean. Levels are well below the objective.

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2.2.3 Sulphur dioxide (SO2)

Wiltshire Council does not undertake any SO2 monitoring. Air quality reporting by the former District Council’s did not identify any issues for this pollutant in any of the former district areas

2.2.4 Benzene

Wiltshire Council does not carry out any Benzene monitoring. Air Quality reporting by the former District Council’s did not identify any issues for this pollutant in any of the former district areas.

2.2.5 Other pollutants monitored

Wiltshire Council does not undertake monitoring for any other pollutants.

2.2.6 Summary of Compliance with AQS Objectives

Wiltshire Council has examined the results from all monitoring in the County. With the exception of two diffusion tube sites, concentrations outside of the AQMA are all below the objectives at relevant locations.

Both of the sites showing an exceedence of the annual mean objective for nitrogen dioxide have already been subject to assessment at the levels reported for 2014 and neither has been shown to exceed the relevant objective at the façade of the nearest relevant exposure.

Therefore there is no need to proceed to a Detailed Assessment although both sites will be relocated to the façade of the nearest relevant exposure to ensure all ambiguity is removed.

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3 Road Traffic Sources

3.1 Narrow congested streets with residential properties close to the kerb

Consideration has been given to locations where traffic is slow moving, with stop/start driving, and where buildings on either side reduce dispersion. This element of the Updating & Screening Assessment only considers NO2. Further information on the detailed criteria followed can be found in Section A1, Box 5.3 of LAQM.TG(09)

Wiltshire Council confirms that there are no new/newly identified congested streets with a flow above 5,000 vehicles per day and residential properties close to the kerb, that have not been adequately considered in previous rounds of Review and Assessment.

3.2 Busy streets where people may spend 1 hour or more close to traffic

Consideration has been given to streets with many shops and/or outdoor cafes and bars where people may be expected to regularly spend 1-hour or more. This element of the Updating & Screening Assessment only considers NO2. Further information on the detailed criteria followed can be found in Section A2, Box 5.3 of LAQM.TG(09).

Wiltshire Council confirms that there are no new/newly identified busy streets where people may spend 1 hour or more close to traffic.

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3.3 Roads with a high flow of Buses and/or HGVs.

Consideration has been given to street locations where traffic flows are not necessarily high but there is an unusually high proportion of buses and/or HGVs.

This element of the Updating & Screening Assessment considers both NO2 and

PM10. Further information on the detailed criteria followed can be found in Section A3, Box 5.3 of LAQM.TG(09).

Wiltshire Council confirms that there are no new/newly identified roads with high flows of buses/HDVs.

3.4 Junctions

Consideration has been given to busy junctions as concentrations of pollution may be higher due to the combined impact of traffic emissions on two roads and the impact of stop start driving. This element of the Updating & Screening Assessment considers both NO2 and PM10. Further information on the detailed criteria followed can be found in Section A4, Box 5.3 of LAQM.TG(09).

Wiltshire Council confirms that there are no new/newly identified busy junctions/busy roads.

3.5 New Roads Constructed or Proposed Since the Last Round of Review and Assessment

Wiltshire Council confirms that there are no new/proposed roads.

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3.6 Roads with Significantly Changed Traffic Flows

This section of the Updating & Screening Assessment only considers those roads that have not been assessed in the criteria above. A significant increase can be considered as a 25% increase in traffic flow on any road with more than 10,000 vehicles per day. This element of the Updating & Screening Assessment considers both NO2 objectives and PM10. Further information on the detailed criteria followed can be found in Section A7, Box 5.3 of LAQM.TG(09).

Wiltshire Council confirms that there are no new/newly identified roads with significantly changed traffic flows.

3.7 Bus and Coach Stations

This section considers bus stations that are not enclosed, and where relevant exposure exists. This element of the Updating & Screening Assessment considers both NO2 objectives (annual mean and 1-hour). Further information on the detailed criteria followed can be found in Section A7, Box 5.3 of LAQM.TG(09)

Wiltshire Council confirms that there are no relevant bus stations in the Local Authority area.

A plan to close the Salisbury Bus Station and reroute buses to various locations within the city centre has been enacted. Wiltshire Council has moved two monitoring sites (P14/92 & P14/39) to the vicinity of bus stops which have been allocated extra bus movements and exhibit relevant exposure in the immediate area. Neither site showed an exceedence of the relevant air quality objective during 2014 but monitoring will continue at these sites.

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3.8 Airports

Consideration has been given to airports with >10 million passengers per annum (100,000 tonnes of freight = 1mppa) and with relevant exposure within 1000m of the airport boundary.

Wiltshire Council confirms that there are no airports in the Local Authority area.

3.9 Railways (Diesel and Steam Trains)

3.9.1 Stationary Trains

Consideration has been given to locations where locomotives, diesel or coal fired, are regularly stationary for a period of 15 minutes or more and where relevant exposure exists. This element of the Updating & Screening Assessment considers just SO2. Further information on the detailed criteria followed can be found in Section B2, Box 5.4 of LAQM.TG(09).

Wiltshire Council confirms that there are no locations where diesel or steam trains are regularly stationary for periods of 15 minutes or more, with potential for relevant exposure within 15m.

3.9.2 Moving Trains

Consideration has been given to sections of tracks with large numbers (>300) moving 3 diesel locomotives, with background NO2 concentrations >25 µg/m and relevant exposure within 30m of the edge of the tracks. This element of the Updating &

Screening Assessment considers just NO2. Further information on the detailed criteria can be found in Table 5.1 and Box 5.4 of LAQM.TG(09).

Table 5.1 identifies Rail lines with a heavy traffic of passing diesel trains. The list includes the line running from Paddington to Swansea, which passes through Wiltshire. However, the guidance states that lines only need to be considered 3 where the background annual mean NO2 concentration is above 25µg/m . This is not exceeded in this area and thus no further assessment is required.

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Wiltshire Council confirms that there are no locations with a large number of movements of diesel locomotives, and potential long-term relevant exposure within 30m.

3.10 Ports (Shipping)

Consideration is given to ports where large ships generally burn oils with high sulphur content in their main engines (bunker oils). This element of the Updating & Screening

Assessment considers just SO2. Further information on the detailed criteria followed can be found in Section B3, Box 5.4 of LAQM.TG(09).

Wiltshire Council confirms that there are no ports or shipping that meets the specified criteria within the Local Authority area.

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4 Industrial Sources 4.1 Industrial Installations

Industrial sources are controlled by the Environment Agency (EA) and by Local Authorities under the Pollution Prevention and Control Regulations and through the Clean Air Act. Many of these sources have been previously assessed in detail in previous reports; therefore focus in this Updating & Screening Assessment is primarily on new installations and those with significantly changed emissions. This section considers all of the regulated pollutants although those most at risk include

SO2, NO2, PM10 and Benzene.

4.1.1 New or Proposed Installations for which an Air Quality Assessment has been carried out

Consideration has been given to new or proposed industrial installations for which an Air Quality Assessment has been carried out. Further information on the detailed criteria followed can be found in Section C1, Approach 1, Box 5.5 of LAQM.TG(09)

Wiltshire Council confirms that there are no new or proposed industrial installations for which planning approval has been granted within its area or nearby in a neighbouring authority.

4.1.2 Existing Installations where Emissions have increased substantially or New Relevant Exposure has been introduced

Consideration has been given to existing industrial installations where emissions have increased substantially or new exposure introduced. Further information on the detailed criteria followed can be found in Section C1, Approach 2, Box 5.5 of LAQM.TG(09)

Wiltshire Council confirms that there are no industrial installations with substantially increased emissions or new relevant exposure in their vicinity within its area or nearby in a neighbouring authority.

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4.1.3 New or Significantly Changed Installations with No Previous Air Quality Assessment

Consideration has been given to new or significantly altered industrial installations for which no Air Quality Assessment has been produced. Further information on the detailed criteria followed can be found in Section C1, Approach 3, Box 5.5 of LAQM.TG(09).

Wiltshire Council confirms that there are no new or proposed industrial installations for which planning approval has been granted within its area or nearby in a neighbouring authority.

4.2 Major fuel (petrol) storage depots

There is the potential for major fuel depots (petrol) to emit benzene and risk exceeding the 2010 objective. This element of the Updating & Screening Assessment considers Benzene only. Further information on the detailed criteria followed can be found in Section C2, Box 5.5 of LAQM.TG(09)

There are no major fuel (petrol) storage depots within the Local Authority area.

4.1 Petrol stations

Petrol stations combined with nearby busy roads may potentially emit sufficient benzene to risk exceeding the 2010 objective. Consideration has been given to all petrol stations with an annual throughput of more than 2000m3 of petrol, with busy roads close by and relevant exposure within 10m of the petrol station pumps. This element of the Updating & Screening Assessment considers Benzene only. Further information on the detailed criteria followed can be found in Section C3, Box 5.5 of LAQM.TG(09).

Wiltshire Council confirms that there are no petrol stations meeting the specified criteria.

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4.2 Poultry farms

Consideration has been given to any poultry farms (defined as chickens (laying hens and broilers), turkeys, ducks and guinea fowl) housing in excess of 400,000 birds (mechanically ventilated), 200,000 birds (naturally ventilated) or 100,000 turkeys (any ventilation) where relevant exposure exists within 100m. This element of the

Updating & Screening Assessment considers PM10 only. Further information on the detailed criteria followed can be found in Section C4, Box 5.5 of LAQm.TG(09).

Below is a table of poultry farms on the Integrated Pollution and Prevention public register (Permitted by the Environment Agency) in Wiltshire.

Table 4.2 Poultry farms permitted by the Environment Agency in Wiltshire

Operator Name & Permitted Type of Relevant Any need to address No. Of ventilation exposure proceed to a birds within Detailed 100m? Assessment? Faccenda Adamsmere 176999 Forced No No Group Ltd Farm, Farley, ventilation, Salisbury side mounted fans, roof outlets Faccenda Marlborough 171249 Forced No No Group Lts Farm, ventilation, Lockeridge, half side Marlborough mounted fans, roof outlets Oaklands Southgrove 634800 Natural No No Farm Eggs Farm, ventilation, Ltd Burbage, Manor Marlborough Farm, tunnel vents Faccenda Langley 437,818 Forced Yes – one YES Group Ltd Burrell, ventilation, residence Sutton Lane, side occupied Sutton mounted by Benger.SN15 fans, roof manager 4LW outlets and family.

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The Faccenda Group site identified at Langley Burrell meets the criteria set out in Section C4, Box 5.5 of LAQM.TG(09) and a detailed assessment will be necessary.

Wiltshire Council has identified a poultry farm meeting the specified criteria, and will need to proceed to a Detailed Assessment for PM10 at this location.

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5 Commercial and Domestic Sources 5.1 Biomass Combustion – Individual Installations

Consideration has been given to large individual installations (50kW to 20 MW in size) burning biomass. This element of the Updating & Screening Assessment considers PM10 and NO2. Further information on the detailed criteria followed can be found in Section D1a, Box 5.8 of LAQM.TG(09).

Wiltshire Council confirms that there are no large biomass combustion plants in the Local Authority area.

5.2 Biomass combustion – combined impacts

Numerous small biomass combustion units, while acceptable individually, may have a cumulative impact on PM10 concentrations. This element of the Updating &

Screening Assessment considers PM10 only. Further information on the detailed criteria followed can be found in Section D1b, Box 5.8 of LAQM.TG(09).

Wiltshire Council confirms that there is no significant concentration of biomass combustion plants in the Local Authority area.

5.3 Domestic solid-fuel burning

Consideration has been given to locations where domestic solid fuel burning (coal) may give rise to exceedences of the SO2 objectives. This element of the Updating and Screening Assessment considers SO2 only. Further information on the detailed criteria followed can be found in Section D2 of LAQM.TG(09).

Wiltshire Council confirms that there are no areas of significant domestic fuel use in the Local Authority area.

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6 Fugitive or uncontrolled sources

Fugitive or uncontrolled sources may give rise to emissions of PM10. This section considers numerous sources such as quarries, landfill sites, stockyards, construction work and waste management sites. Consideration is given to elements such as: • The passage of vehicles over unpaved roads; • Handling of dusty materials; • Process dust e.g. concrete cutting; and • Windblown dust from stockpiles and dusty surfaces.

This element of the Updating & Screening Assessment considers PM10 only. Further information on the detailed criteria followed can be found in section E1, Box 5.10 of LAQM.TG(09).

Wiltshire Council confirms that there are no potential sources of fugitive particulate matter emissions in the Local Authority area.

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7 Conclusions and proposed actions

7.1 Conclusions from new monitoring data

The Air Quality Monitoring undertaken by Wiltshire Council during 2014 confirms that all declared Air Quality Management Areas are still valid and should remain. No extra assessment of monitoring outside of the established or proposed AQMA’s is required.

Exceedences were identified within existing or proposed AQMAs at the following locations:

Salisbury P14/30 – 74 London Road P14/38 – 123 South Western Road P14/46 – 17 Wilton Road P14/88 – 225 Wilton Road* P14/47 – 31 Devizes Road P14/49 – 91 Exeter Street

Bradford on Avon P14/0 – 9 Masons Lane P14/76 – 12 Market Street

Devizes P14/14 – 5 The Nursery P14/13 – Shanes Castle P14/12 – Opposite Wadworths, 41 Northgate Street P14/15 – 105 St James Place

Marlborough P14/22 – 6 Herd Street P14/25 – 27 Herd Street

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P14/26 – 6 Barn Street P14/27 – 13 Salisbury Road P14/29 – 115 London Road

Calne P14/3 – 18 Curzon Street P14/5 – King George, 74 New Road

Westbury P14/0 – 71 Warminster Road

* Within a proposed AQMA

7.2 Conclusions from assessment of sources

This Updating and Screening Assessment has concluded the following:

• This assessment has indicated that there are no road transport sources of concern in the Wiltshire area that have been identified since the last Updating and Screening Assessment in 2012, and therefore a Detailed Assessment is not required.

• This assessment has indicated that there are no other transport sources of concern in the Wiltshire area that have been identified since the last Updating and Screening Assessment in 2012, and therefore a Detailed Assessment is not required.

• This assessment has indicated that apart from one Poultry Farm, there are no industrial sources of concern in the Wiltshire area that have been identified since the last Updating and Screening Assessment in 2012.

• This assessment has indicated that there are no commercial and domestic

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sources of concern in the Wiltshire area that have been identified since the last Updating and Screening Assessment in 2012, and therefore a Detailed Assessment is not required.

• This assessment has indicated that there is no fugitive or uncontrolled sources of concern in the Wiltshire area that have been identified since the last Updating and Screening Assessment in 2012, and therefore a Detailed Assessment is not required.

• That the Faccenda Group Poultry Farm site at Langley Burrell meets the criteria set out in Section C4, Box 5.5 of LAQm.TG(09) and a detailed

assessment for levels of PM10 will be necessary.

7.3 Proposed actions

This Updating and Screening Assessment has identified a need to proceed to a

Detailed Assessment for PM10 at a poultry farm within Wiltshire.

Additionally, It is proposed that the two diffusion tube monitoring sites outside of the

AQMA’s but showing an exceedence of the annual mean objective for NO2 are moved to the façades of relevant exposure in the vicinity of their current locations.

The level of exceedence reported in 2014 has been reported previously and assessed as not exceeding the objective at relevant exposure once the fall off due to distance was taken into account. Moving the sites will allow us to establish the validity of these conclusions.

Diffusion tube monitoring sites have also been established in the town of Royal Wotton Bassett following concern expressed by a local councillor. Results from the 3 new sites will be presented in the 2016 Progress Report.

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Appendix A: QA/QC Data

Factor from Local Co-location Studies (if available)

No correction factor has been calculated for the Wiltshire Council co-located diffusion tubes for 2014.

Diffusion Tube Bias Adjustment Factors

The National Bias Correction Factor calculated by the LAQM helpdesk for diffusion tubes analysed by Gradko, 20% TEA in water is 0.91 and can be seen in the spreadsheet below:

PM 10 monitoring adjustment

Data from Wiltshire Council automatic analysers is handled by Ricardo AEA who have confirmed the following:

Bradford on Avon has a factor of 0.8333 applied to it as it has unheated inlet. Devizes and Salisbury have a factor of 1.3 applied to their data as the inlet is heated.

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QA/QC of automatic monitoring (Salisbury and Devizes continuous analysers)

Data management and reporting is carried out mainly through the Ambient Air Quality Central Software package IDAZRW. The station is polled automatically from a PC of Environmental Services via a GSM modem. The poll occurs three times daily at 00:00 hours, 08:00 hours and 13:00 hours. The PC remains switched on constantly. Features of the software include:

• Automatic calibration every 73 hours • Automatic redial on busy line or after communication failure • Detailed logs of data requests and transmission problems • Remote control of stations for zero test, test gas, measuring range and calibrations • Calculation of scaling factors and application to nearest results following each automatic calibration • Marking of abnormal readings, negative readings or readings taken during • instrument failure or calibration • Deletion of abnormal readings

Manual scaling is, therefore, not required. The auto-scaling feature means that the figures are more frequently scaled than the accepted manual scaling operation on a two-weekly basis. Data is checked manually at least weekly, more normally daily, to ensure that the software is making the correct adjustments. There should, therefore, be no requirement to manually back-correct and abnormal readings are marked.

During the calibration checks a manual note is taken of span and zero and NO2 gas readings, any abnormal conditions or error readings and any actions taken.

Manual calibrations are compared with auto-calibration. At 6 monthly intervals the data is compared with the nearest AURN site. Any abnormal data will be discarded unless it can be traced to a local event. The correction factors are recorded in the calibration report and any local anomalous results are investigated for example local location of a generator for roadworks.

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QA/QC of automatic monitoring (Bradford on Avon and Calne continuous analysers)

Automatic calibration

To ensure that the information obtained from the analysers is as accurate as possible and to quantify any instrument drifts a stringent QA/QC protocol is followed.

The API M200A analyser is subjected to daily automatic calibration. This provides a daily check on the performance of the instrument. It should be noted that these results are not used for instrument scaling.

The zero air is generated by passing ambient air through purafil charcoal scrubbers before it is passed into the reaction cell. The span gas is generated by an NO2 permeation tube containing pure liquid NO2. The permeation tube is enclosed in an oven, which is maintained at a constant temperature. The zero air is passed across the permeation tube at a constant flow rate. Provided the flow rate and temperature are kept constant, the amount of NO2 permeating from the tube into the air stream will be constant. The gas then produced then passes into the reaction cell and a span calibration response is determined.

The data is collected as 1-hour averages. The data is uploaded from the analyser via modem to the AQA-Ricardo team who check scale and publish the data on the website; . http://www.wiltshireairquality.org.uk/

Manual calibration

Every two weeks manual calibration checks are carried out on the API M2000 analysers. This allows the instrument drifts to be fully qualified and documented using traceable calibration gas standards and the results are used to scale data.

At the time of the instrument calibration checks, instrument pre-calibration checks are made to ensure that the condition of the analyser, before the calibration check, is assessed and any faults attended to. .

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The fortnightly calibration procedure requires a zero check on the analyser. This is achieved by a source of zero air being provided by passing ambient air through the charcoal scrubber before it enters the reaction cell. Once stability has been achieved (this is defined as a variation of less than 0.1ppb over a one minute period for the analyser) three readings are recorded from the instrument display after three ten second intervals. Next the calibration gas bottle is opened at a pressure of 30 psi. The analyser is allowed to stabilise for a minimum of ten minutes. Three consecutive readings are taken from the instrument display, allowing ten seconds between readings. The calibration gas is then isolated.

By considering the previous calibration results and the results obtained from the calibration just performed, the success of the calibration procedure is determined. The zero value should not differ by more than ± 2ppb from the previous calibration. The span calibration should not differ by more than 5% from that obtained during the previous calibration. Additionally, the analyser sample inlet filter is changed when necessary.

Six monthly checks

These checks are carried out by our current contractor, Matts Monitors Limited, at the same time as they service the equipment. They ensure that the measurements from the analyser are representative and inter-comparable. The calibrations act as an independent audit of the system performance. Additionally, any site-specific problems that may have remained undetected will be fully quantified.

QA/QC of diffusion tube monitoring

Laboratory and preparation information

Wiltshire Council utilises diffusion tubes prepared and analysed by Gradko Ltd. The laboratory participates in the Workplace Analysis Scheme for Proficiency (WASP) for nitrogen dioxide tubes. They analyse a solution supplied by Netcen as part of the QA/QC scheme that they run. The laboratory also participates in a field inter- comparison scheme which is controlled by Netcen and organised by the Health and Safety Laboratory.

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Three tubes are co-located with a continuous analyser which provides a reference value. The tubes are prepared by pipetting 30µl of solution of 20% triethanolamine in water onto the metal grids in the end of the cap, then assembling the tube components. A fresh batch of tubes is prepared each month ready to dispatch in time for the required exposure date. Laboratory blanks are retained so that at least one is run alongside each batch of samples. Travel blanks are supplied monthly as required by the UK survey procedure.

Laboratory QA/QC The WASP Scheme is an independent proficiency testing scheme operated by the Health and Safety Laboratory (HSL). Each month a diffusion tube doped with nitrite is distributed to each participating laboratory; participants then analyse the tube and report the results to HSL. The nominal mass of nitrite on the doped tubes is different each month, and is intended to reflect the range encountered in actual monitoring. For the purpose of diffusion tube QA/QC in the context of Local air Quality Management, AEA Energy & Environment carry out an assessment of laboratory performance for each full calendar year. This was based on the following criteria, which were agreed with Defra and HSL:

• Participating laboratories must complete at least 10 of the 12 monthly WASP rounds. • The year’s single worst result is ignored: this makes some limited allowance for one-off problems with analytical equipment etc. • Each laboratory’s monthly standardised results are then combined to give a standard uncertainty for the full year, expressed as a relative standard deviation (%RSD). • The RSD must be within 15%.

Mean Standardised result (actual result / nominal value): 0.98. Mean percentage under/over-estimation of analysis: -1.5%. Comparison with AEA performance criteria for Local Authority Support: RSD of Standardised Results, ignoring worst value: 4.0 % - this is within the performance target of 15%.

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Comments: The laboratory's WASP results met AEA Energy & Environment's performance criteria in 2014.

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