2011 Air Quality Detailed Assessment Report Epping Forest District Council

Transcription

1 2011 Air Quality Detailed Assessment Report Epping Forest District Council In fulfillment of Part IV of the Environment Act 1995 Local Air Quality Management August, 2011

2 Local Authority Officer: Fay Rushby Department: Address: Environment & Street Scene Epping Forest District Council Civic Offices High Street Epping CM16 4BZ Telephone: Report Ref: WK/ Date: August, 2011 As part of the: Essex Air Quality Consortium Monitoring Network. ii 2011 Detailed Assessment Report

3 Executive Summary The Epping Forest 2011 Air Quality Progress Report identified that measured levels of nitrogen dioxide were at or above the air quality objective for certain high street monitoring locations in Epping and Loughton. The data from the 2011 Progress Report was used in this detailed assessment to determine the extent of the exceedence area, using tools available from the defra air quality web pages. The initial results of the detailed assessment confirmed that just over 60 premises may be affected in Loughton and around 20 premises in Epping, and that two new town centre AQMA s were likely. July 2011 however brought in a revised bias adjustment factor for the diffusion tubes used by Epping Forest District Council. The revised bias adjustment factor radically altered the initial results of the detailed assessment, such that no areas of Epping High Street were at or above the air quality objective level for nitrogen dioxide, and that the number of premises affected in Loughton may be reduced to 20. The detailed assessment also determined that monitoring at elevated height equivalent to receptor height also had an impact on the levels of nitrogen dioxide reported, and that ground floor concentrations may substantially over-estimate first and second floor receptor exposure. Given the significant change in bias adjustment factor and the apparent over-estimation of first and second floor receptor exposure using data gathered from ground floor level, it is considered that the data is too uncertain to declare any further AQMA s (particularly borderline town centre ones) at this time. The following actions are however proposed: 1. To increase the height of monitoring tubes above ground level (done June/July 2011). 2. To continue monitoring at increased height above ground level for the remainder of To review 2011 data and complete a further DA (with modelling if resources allow). 4. To declare an AQMA for either location when data is reliable enough to do so. 5. To deploy further diffusion tube (re-use tubes from other monitoring locations) if further actual monitoring data is required (from January Detailed Assessment Report iii

4 Table of contents 1 Introduction Backround Purpose of the Detailed Assessment Report Air Quality Objective 7 2 Detailed Assessment Site Descriptions Epping High Street Loughton High Road Monitoring Methods and Monitoring Locations Monitoring Methods Epping High Street Monitoring Locations Loughton High Road Monitoring Locations Monitoring Data Review Epping High Street Loughton High Road Receptor Assessment Epping High Street Loughton High Road 19 3 Conclusions and Proposed Actions Conlusions Proposed Actions 23 4 References 24 iv 2011 Detailed Assessment Report

5 Appendices Appendix A Appendix B Appendix C Raw diffusion tuba data QA:QC Diffusion tubes Diffusion Tube Bias Adjustment Factor List of Tables Table 1 Nitrogen Dioxide Air Quality Objective for the purpose of Local Air Quality Management in England. Table 2 Traffic count data by vehicle type for the A121, Loughton High Road ( Table 3 Details of Non- Automatic Monitoring Sites in Epping High Street Table 4 Details of Non- Automatic Monitoring Sites in Loughton High Road Table 5 Annual Mean Concentrations of Nitrogen Dioxide for Epping High Street Table 6 Annual Mean Concentrations of Nitrogen Dioxide for Loughton High Road Table 7 Assessment of the drop-off in Nitrogen Dioxide Concentration with Distance from the Kerb for Sensitive Receptors in Epping High Street using 2010(A) data. Table 8 Assessment of the drop-off in Nitrogen Dioxide Concentration with Distance from the Kerb for Sensitive Receptors in Loughton High Road using 2010(A) data. Table 9 Assessment of the drop-off in Nitrogen Dioxide Concentration with Distance from the Kerb for Sensitive Receptors in Loughton High Road using 2010(B) data. List of Figures Figure 1 Epping High Street Diffusion Tube Monitoring Locations. Figure 2 Loughton High Road Diffusion Tube Monitoring Locations. Figure 3 National Diffusion Tube Bias Adjustment Factor Spreadsheet (04/11 release). Figure 4 National Diffusion Tube Bias Adjustment Factor Spreadsheet (06/11 release). Figure 5 Sensitive Receptors in Epping High Street (in yellow). Figure 6 Sensitive Receptors in Epping High Street (in red) with the Potential to Exceed the Air Quality Objective using 2010(A) data. Figure 7 Sensitive Receptors in Loughton High Road (in yellow). Figure 8 Receptors in Loughton High Road (in red) with the potential to be at or above the nitrogen dioxide air quality Objective using 2010(A) data. Figure 9 Receptors in Loughton High Road (in red) with the potential to be at or above the nitrogen dioxide air quality Objective using 2010(B) data Detailed Assessment Report v

6 1 Introduction 1.1 Background Epping Forest District is an attractive, predominantly commuter area on the north eastern edge of London. The district has a population of around 121,000, of which nearly three quarters live in the suburban towns of Loughton, Buckhurst Hill, Chigwell, Epping and Waltham Abbey. The remaining quarter live in the surrounding rural areas including large villages such as Roydon, Nazeing, North Weald and Theydon Bois. The main source of air pollution in the borough is road traffic. There are two large motorways in the district; the M25 and the M11 however the air quality issues are located in the urban areas monitoring data and the 2009 Updating and Screening Assessment started to indicate that there was a risk of exceeding the annual air quality objective for nitrogen dioxide in the town centre locations of Epping High Street and Loughton High Road. The 2009 monitoring data and 2010 progress report confirmed that the position was not improving, but because relevant exposure is at first floor level above the shops, diffusion tubes should be located higher up the building façade to better represent actual exposure. This was undertaken at the start of 2010 for Ladbrokes, Epping, (a site having good access) as a pilot site to see if the move to an elevated level had an appreciable impact on the data reported. Data was also gathered throughout 2010 for receptor and non-receptor locations in Epping and Loughton. The data gathered specifically for these locations is reviewed an assessed in more detail in this report. 1.2 Purpose of the Detailed Assessment Report The purpose of the detailed assessment is to focus on locations where members of the public are likely to be exposed to nitrogen dioxide in excess of the air quality objective over the averaging period of the air quality objective (in this case, the annual nitrogen dioxide objective). In particular, this report aims to: Review historical nitrogen dioxide data for Epping High Street and Loughton High Road, and; Confirm the presence of sensitive receptors at floor level above shops in Epping High Street and Loughton High Road, and; Determine the residential receptors likely to be subject to nitrogen dioxide concentrations in excess of the air quality objective, and; Consider the data gathered during the 2010 monitoring campaign and its suitability for the determination of any Air Quality Management Area, and; Determine whether an Air Quality Management Area (or areas) should be declared. In this detailed assessment, the Council has not engaged the services of a third party consultant for dispersion modelling due to the absence of resources. This report uses tools available from the defra web site in its assessment of likely nitrogen dioxide concentration at receptor façade where actual monitoring is not undertaken or where the receptor is set nearer to or further back from the kerb than the monitoring location Detailed Assessment Report

7 1.3 Air Quality Objective The air quality objectives applicable to Local Air Quality Management (LAQM) in England are set out in the Air Quality (England) Regulations 2000 (SI 928), and the Air Quality (England) (Amendment) Regulations 2002 (SI 3043). They are shown in Table 1.1. This table shows the objectives in units of microgrammes per cubic metre µg/m 3. Table 1 includes the number of permitted exceedences in any given year (where applicable). Table 1: Nitrogen Dioxide Air Quality Objective for the purpose of Local Air Quality Management in England. Pollutant Concentration Measured as Date to be achieved by Nitrogen dioxide 200 µg/m 3 not to be exceeded more than 18 times a year 1-hour mean µg/m 3 Annual mean Detailed Assessment Report 7

8 2 Detailed Assessment 2.1 Site Descriptions Epping High Street Epping lies 17 miles (27.4 km) north-east of the centre of London, and lies north-east of junction 26 of the M25 motorway and south-west of junction 7 of the M11 motorway. Nitrogen dioxide emissions are solely from road traffic sources. Epping High Street is the B1393 running south west to north east through the centre of the market town of Epping. No detailed breakdown of traffic data is available for this road. AADF traffic data is in the order of 14,500. At approximately 590m in length, the centre of Epping High Street from Crows Road in the south west to the civic offices in the north east is a typical, fairly wide, market town street with relatively high buildings flanking a congested road. Three pedestrian traffic crossings (two signal controlled, one zebra crossing) also contribute to the stop-start nature of the traffic flow. Kerbside parking is also provided. Any flow problem or closure on the M25 or M11 motorways can also lead to the High Street being used as an alternative route between junction 26 of the M25 and junction 7 of the M Loughton High Road Loughton lies south of the M25 and west of the M11 motorway. Nitrogen dioxide emissions are solely from road traffic sources. Loughton High Road is the A121 running south west to north east through the centre of Loughton town. The High Road has an AADF of 13,199 for all motor vehicles. A detailed breakdown of traffic data is available for this road, and is detailed in table 2. Table 2: Traffic count data by vehicle type for the A121, Loughton High Road ( LName Road PC 2WMV CAR BUS LGV HGV All_MV Essex County Council A The count data shows that cars account for 85% of the road traffic, with busses and HGV at 1.1 and 1.9% respectively. At approximately 820m in length, the centre of Loughton High Road from Old Station Road in the south west to Church Hill in the north east is a typical, fairly wide, market town street with relatively high buildings flanking a congested road. Four pedestrian traffic crossings (three signal controlled, one zebra crossing) and a signal controlled junction also contribute to the stop-start nature of the traffic flow. Kerbside parking is also provided. Any flow problem or closure on the M25 or M11 motorways can also lead to the High Road being used as an alternative route to the M25 and M11 Motorways. The A121 is also a direct route out of London, flowing from the A Detailed Assessment Report

9 2.2 Monitoring Methods and Monitoring Locations Monitoring Methods Non-automatic monitoring undertaken in the district is exclusively via NO 2 diffusion tubes. The diffusion tubes are supplied by Environmental Scientific Groups (ESG) in accordance with the procedures set out in the Practical Guidance document. They are of the 50% Triethanolamine (TEA) in acetone Preparation Epping High Street monitoring locations 9 diffusion tubes are installed at 3 monitoring locations in Epping High Street. A map showing the monitoring locations is shown as figure 1. Site details are given in table 3 Figure 1: Epping High Street Diffusion Tube Monitoring Locations Detailed Assessment Report 9

10 Table 3 Details of Non- Automatic Monitoring Sites in Epping High Street Map ref Site ref Site name Within AQMA? /20/21 (triplicate) 2/10/35 (triplicate) 1/8/44 (triplicate) 15 High Street, Epping No Outside Superdrug, 202 High Street, Epping Ladbrokes, High Street, Epping 15 High Street, Epping is a residential house set back from the road. Diffusion tubes are mounted approximately 1.75m above ground level. The road is free from significant road features at this point (i.e. no junctions or crossings). Superdrug, 202 High Street, Epping is a high street location whose shop façade is directly on the pavement. Diffusion tubes were mounted approximately 2.0m above ground level throughout The monitoring location is close to a traffic light controlled pedestrian crossing and kerbside parking. Ladbrokes, High Street, Epping is a high street location whose shop façade is directly on the pavement. Diffusion tubes are mounted approximately 3.0m above ground level. The monitoring location is close to a traffic light controlled pedestrian crossing. No No Loughton High Road monitoring locations 9 diffusion tubes are installed at 4 monitoring locations in Loughton High Road. A map showing the monitoring locations is shown as figure 2. Site details are given in table 4. Table 4: Details of Non- Automatic Monitoring Sites in Loughton High Road Site ref Site ref Site name Within AQMA? /28 (duplicate) 17/18 (duplicate) 4/25 (duplicate) 14/23/27 (triplicate) 72 Church Hill, Loughton No Zizzi, 2 Church Hill, Loughton Pink, 252 High Road, Loughton Timpson, 249 High Road Loughton No No No Detailed Assessment Report

11 Figure 2: Loughton High Road Diffusion Tube Monitoring Locations. 72 Church Hill, Loughton is a residential house set back from the road. Diffusion tubes are mounted approximately 1.75m above ground level. Zizzi, 2 Church Hill, Loughton is a high street location whose shop façade is directly on the pavement. Zizzi s is an Italian restaurant, and it was previously considered that there was residential accommodation above the restaurant. This has been confirmed as not being the case, so there are no sensitive receptors at the Zizzi s monitoring location. Diffusion tubes were mounted approximately 2.0m above ground level throughout Pink, 252 High Road, Loughton is a high street location whose shop façade is directly on the pavement. Diffusion tubes were mounted approximately 2.0m above ground level throughout The monitoring location is close to a traffic light controlled pedestrian crossing and is immediately adjacent to a bus stop. Timpson, 249 High Road Loughton is a high street location whose shop façade is directly on the pavement. Diffusion tubes were mounted approximately 2.0m above ground level throughout The monitoring location is close to a traffic light controlled pedestrian crossing and kerbside parking Detailed Assessment Report 11

12 2.3 Monitoring Data Review Diffusion tube monitoring data has been gathered over at least three years for both the Epping High Street and Loughton High Road monitoring locations. Non-automatic monitoring undertaken in the district is exclusively via NO 2 diffusion tubes. The diffusion tubes are supplied by Environmental Scientific Groups (ESG) in accordance with the procedures set out in the Practical Guidance document. They are of the 50% Triethanolamine (TEA) in acetone Preparation. ESG are classified as achieving Good performance in the Workplace Analysis Scheme for Proficiency (WASP) Report for rounds Further details on WASP performance can be found in Appendix B & C In the absence of a local bias correction factor, the default bias correction factor for ESG analysis using the 50% TEA in acetone method has been used. This factor, calculated as 0.83 for 2010 based on 3 studies has been obtained from the defra air quality website (April 2011 release): See figure 3. Figure 3: National Diffusion Tube Bias Adjustment Factor Spreadsheet (04/11 release). A bias adjustment factor of 0.83 was applied to the average of the raw diffusion tube data for the 2010 calendar year as part of the 2011 progress report data assessment which led to the need for this detailed assessment Detailed Assessment Report

13 Since the progress report, a revised spreadsheet has been issued which substantially changed the bias adjustment factor for tubes are supplied by ESG to 0.75 See figure 4. Figure 4: National Diffusion Tube Bias Adjustment Factor Spreadsheet (06/11 release). Whilst a legitimate bias adjustment factor, it is noted that this may be a temporary variation based on the quantity and quality of the data gathered for the study, therefore both bias adjustment factors have been used in this detailed assessment Detailed Assessment Report 13

14 2.3.1 Epping High Street The last three years, bias adjusted, monitoring data for Epping High Street is detailed in table 5. The full unadjusted annual average data for the year is in Appendix A. Table 5: Annual Mean Concentrations of Nitrogen Dioxide for Epping High Street Map ref Site name Relevant public exposure? Foot notes: Annual mean concentrations (mg/m 3 ) at monitoring location (A) (B) 4 4 Ladbrokes, High Street, Epping Yes, at 1 st floor level only Superdrug, 202 High Street, Epping Yes, at 1 st floor level only High Street, Epping Yes, at monitoring location Gradko 50% TEA in Acetone, 2008 bias adjustment factor: 0.93 Gradko 50% TEA in Acetone, 2009 bias adjustment factor: 0.99 Environmental Scientifics Group 50% TEA in Acetone, 2010 bias adjustment factor: 0.83 Environmental Scientifics Group 50% TEA in Acetone, 2010 bias adjustment factor: (A) data for Epping High Street in table 5 was derived using the April 2011 revision to the bias adjustment factor spreadsheet. 2010(A) data for Epping High Street indicates a 2 to 3µg/m 3 improvement in the concentrations of nitrogen dioxide from 2009 to 2010 at the 202 and 15 High Street monitoring locations respectively, meaning that 2010 annual mean concentrations were more in line with 2008 annual means for the same locations. This is likely to be attributable to general improvements in air quality through the general upgrade of the national vehicle fleet, and the completion of the M25 tunnel works meaning that less traffic was displaced to local roads. No current traffic data is however available to substantiate this. The 2010(A) monitoring data also indicates a more substantial 6µg/m 3 improvement in the concentration of nitrogen dioxide at the Ladbrokes monitoring location from 43µg/m 3 in 2009 to 37µg/m 3 in Indeed 2010(A) data now indicates that nitrogen dioxide concentrations do not exceed the annual average nitrogen dioxide air quality objective at this location. In addition to the improvements in air quality detailed above, the improvement at this site may also be attributed to increasing the height of the diffusion tubes to at least 3 metres above ground level to better represent exposure at first floor level in the flats above the shops. Whilst concentrations of nitrogen dioxide remain above the objective level for the Superdrug monitoring location at 42µg/m 3, the annual average represents ground floor concentrations, rather than first floor concentrations where the receptors are located. Given the difference in concentration noted at 2m above ground level compared to 3 metres above ground level at the Ladbrokes monitoring location, it is considered that the 2010(A) data for the Superdrug monitoring location is likely to over-estimate actual exposure at first floor level in the flats above the shops Detailed Assessment Report

15 2010(B) data for Epping High Street in table 5 was derived using the June 2011 revision to the bias adjustment factor spreadsheet. 2010(B) data for Epping High Street indicates that nitrogen dioxide concentrations are all below 40µg/m 3 and do not exceed the annual average nitrogen dioxide air quality objective at any monitoring location along Epping High Street Loughton High Road The last three years, bias adjusted, monitoring data for Loughton High Road is detailed in table 6. The full unadjusted annual average data for the year is in Appendix A. Table 6: Annual Mean Concentrations of Nitrogen Dioxide for Loughton High Road Map ref Site name Relevant public exposure? Annual mean concentrations (mg/m 3 ) at monitoring location Church Hill, Loughton Yes, at monitoring location Zizzi, 2 Church Hill, Loughton No Pink, 252 High Road, Loughton Yes, at 1 st floor level only Timpson, 249 High Road Loughton Yes, at 1 st floor level only Foot notes: Gradko 50% TEA in Acetone, 2008 bias adjustment factor: 0.93 Gradko 50% TEA in Acetone, 2009 bias adjustment factor: 0.99 Environmental Scientifics Group 50% TEA in Acetone, 2010 bias adjustment factor: 0.83 Environmental Scientifics Group 50% TEA in Acetone, 2010 bias adjustment factor: (A) data for Loughton High Road in table 6 was derived using the April 2011 revision to the bias adjustment factor spreadsheet. 2010(A) data for Loughton High Road indicates a 1 to 3µg/m 3 improvement in the concentrations of nitrogen dioxide from 2009 to 2010 at the 252 and 249 High Street monitoring locations respectively, however 2010 annual mean concentrations are still above 2008 annual means for the same locations. Given the difference in concentration noted a 2m above ground level compared to 3 metres above ground level at the Ladbrokes monitoring location in Epping, it is considered that the 2010(A) data for the Zizzi, Pink and Timpson monitoring locations are likely to over-estimate actual exposure at first floor level in the flats above the shops. Concentrations of nitrogen dioxide have remained fairly static below the air quality objective at 32µg/m 3 at 72 Church Hill, which is set back from the road Detailed Assessment Report 15

16 2010(B) data for Loughton High Road in table 6 was derived using the June 2011 revision to the bias adjustment factor spreadsheet. 2010(B) data for Loughton High Road indicates that (with the exception of the Pink monitoring location) nitrogen dioxide concentrations are all below 40µg/m 3 and do not exceed the annual average nitrogen dioxide air quality objective. 2010(B) data for the Pink monitoring location at 252 High Road indicates that the annual average nitrogen dioxide concentration is 42µg/m 3, but given the difference in concentration noted at 2m above ground level compared to 3 metres above ground level at the Ladbrokes monitoring location, it is considered that the 2010(B) data for the Pink monitoring location is likely to over-estimate actual exposure at first floor level in the flats above the shops. Diffusion tube monitoring results for 2010 for both Epping High Street and Loughton High Road do not therefore provide a clear basis for making a reliable decision regarding the declaration of any further Air Quality Management Areas for the Epping Forest District. The principal influencing factor being the bias adjustment factor and secondly, the height of the monitoring location above ground level. The June 2011 revision of the bias adjustment factor spreadsheet changed the bias adjustment factor of 0.83 to Whilst a legitimate bias adjustment factor, it is noted that this may be a temporary variation based on the quantity and quality of the data gathered for the study. In June 2011, the Superdrug, Timpson, Zizzi and Pink monitoring locations with relevant exposure at first floor level were increased in height to 3m above ground level (or as near as possible) to better represent actual exposure on first and second floors Detailed Assessment Report

17 2.4 Receptor Assessment The 2010 monitoring data has indicated that there is potential for the nitrogen dioxide air quality objective to be exceeded in both Epping High Street and Loughton High Road, however changes to the bias adjustment factor means that there is doubt over air quality objective exceedence locations, the extent of any zone of exceedence, and the estimated population exposed to concentrations of nitrogen dioxide at or above the annual air quality objective. The actual locations of sensitive receptors at first floor level in both Epping High Street and Loughton High Road have however been determined for the purposes of planning the boundaries of any potential AQMA, should any new bias adjustment factor be less favourable than that in the June 2011 revision of the spreadsheet. This in turn will help to estimate the population exposed to concentrations of nitrogen dioxide at or above the annual air quality objective (if any) Epping High Street Sensitive receptors in Epping High Street are all at or above first floor level. Some receptors are set further back from the kerb than others, which will also have an effect on nitrogen dioxide concentrations. Sensitive receptors (all residential) in Epping High Street are shown in figure 5. Figure 5: Sensitive Receptors in Epping High Street (in yellow) Ladbrokes Superdrug Pedestrian crossing 2011 Detailed Assessment Report 17

18 In a simple assessment of the drop-off in nitrogen dioxide concentration with distance from the kerb (using the defra excel tool: some the receptors shown in figure 5 are unlikely to exceed the air quality objective using the 2010(A) data. The annual average of 42µg/m 3 from the Superdrug monitoring location was used in this assessment. The results of that assessment are shown in table 7 and figure 6. Table 7: Assessment of the drop-off in Nitrogen Dioxide Concentration with Distance from the Kerb for Sensitive Receptors in Epping High Street using 2010(A) data. Figure 4 ref Location Monitoring distance from kerb (m) Receptor distance from kerb (m) Local annual mean background concentration (mg/m 3 ) Measured mean concentration (mg/m 3 ) Predicted annual mean concentration at receptor(mg/m 3 ) 1 Crows Road Flats High Street High Street High Street High Street High Street High Street High Street Figure 6: Sensitive Receptors in Epping High Street (in red) with the Potential to Exceed the Air Quality Objective using 2010(A) data Detailed Assessment Report

19 The population exposure using the properties identified in figure 6 as likely to exceed the nitrogen dioxide air quality objective is conservatively estimated to be in the order of individuals, assuming that every property identified as being residential was actually occupied. No exceedences are reported using the 2010(B) monitoring data, consequently there will be no population exposure to concentrations of nitrogen dioxide above the annual average air quality objective for Epping High Street Loughton High Road Sensitive receptors in Loughton High Road are all at or above first floor level. Some receptors are set further back from the kerb than others, which will also have an effect on nitrogen dioxide concentrations. Sensitive receptors (all residential) in Loughton High Road are shown in figure 7. Figure 7: Sensitive Receptors in Loughton High Road (in yellow) Zizzi Pink Pedestrian crossing Timpson 2011 Detailed Assessment Report 19

20 Table 8: Assessment of the drop-off in Nitrogen Dioxide Concentration with Distance from the Kerb for Sensitive Receptors in Loughton High Road using 2010(A) data. Figure 6 ref Location Monitoring distance from kerb (m) Receptor distance from kerb (m) Local annual mean background concentration (mg/m 3 ) Measured mean concentration (mg/m 3 ) Predicted annual mean concentration at receptor(mg/m 3 ) Church Hill Church Hill Kings Green High Road Brooklyn Court High Road /186 High Road High Road * 177 & 183 High Road * Connaught Mews * High Road * 119 & 121 High Road * 2 Lower Park road 117 high Street * High Road * less congestion in these areas, therefore predicted annual mean estimates may be over-estimates Figure 8: Receptors in Loughton High Road (in red) with the potential to be at or above the nitrogen dioxide air quality Objective using 2010(A) data Detailed Assessment Report

21 In a simple assessment of the drop-off in nitrogen dioxide concentration with distance from the kerb (using the defra excel tool: some the receptors shown in figure 7 are unlikely to exceed the air quality objective using the 2010(A) data. The annual average from the closest monitoring location was used in the assessment to assess each discrete section of the road as numbered in figure 7. The results of that assessment are shown in table 8 and figure 8. The population exposure using the properties identified in figure 6 as likely to exceed the nitrogen dioxide air quality objective is conservatively estimated to be in the order of individuals, assuming that every property identified as being residential was actually occupied. In a simple assessment of the drop-off in nitrogen dioxide concentration with distance from the kerb (using the defra excel tool: more of the receptors shown in figure 7 are unlikely to exceed the air quality objective using the 2010(B) data. The annual average from the closest monitoring location was used in the assessment to assess each discrete section of the road as numbered in figure 7. The results of that assessment are shown in table 9 and figure 9. The population exposure using the properties identified in figure 6 as likely to exceed the nitrogen dioxide air quality objective is conservatively estimated to be in the order of individuals, assuming that every property identified as being residential was actually occupied. Table 9: Assessment of the drop-off in Nitrogen Dioxide Concentration with Distance from the Kerb for Sensitive Receptors in Loughton High Road using 2010(B) data. Figure 6 ref Location Monitoring distance from kerb (m) Receptor distance from kerb (m) Local annual mean background concentration (mg/m 3 ) Measured mean concentration (mg/m 3 ) Predicted annual mean concentration at receptor(mg/m 3 ) Church Hill Church Hill Kings Green High Road Brooklyn Court High Road /186 High Road High Road * 177 & 183 High Road * Connaught Mews * High Road * 119 & 121 High Road * 2 Lower Park road 117 high Street * High Road * less congestion in these areas, therefore predicted annual mean estimates may be over-estimates 2011 Detailed Assessment Report 21

22 Figure 9: Receptors in Loughton High Road (in red) with the potential to be at or above the nitrogen dioxide air quality Objective using 2010(B) data Detailed Assessment Report

23 3 Conclusions and proposed actions 3.1 Conclusions This assessment has determined that areas of Epping High Street and Loughton High Road are likely to be at or above the air quality objective for nitrogen dioxide at ground floor level; however receptors are at first floor level or higher. Exposure to concentrations of nitrogen dioxide at or above the air quality objective may occur at receptors at first floor level or higher, resulting in approximately 60 affected properties in Loughton and a maximum estimated population exposure in the order of 150 residents; and approximately 20 affected properties in Epping and a maximum estimated population exposure in the order of 50 residents However changes to national bias adjustment factors radically alter the number of properties that might be affected, resulting in approximately 20 affected properties in Loughton and a maximum estimated population exposure in the order of 50 residents; and no properties in Epping. Changes in the height of monitoring location also significantly impact on the measured concentrations of nitrogen dioxide This report has identified the likely extent of the zones of exceedence given both current and previous bias adjustment factors, but given the variation in bias adjustment factors, it is considered prudent to suspend the decision to declare any further AQMA s at this time, particularly as they are town centre locations. 3.2 Proposed actions The proposed actions in response to this detailed assessment are as follows: 1. To increase the height of monitoring tubes above ground level (done June/July 2011). 2. To continue monitoring at increased height above ground level for the remainder of To review 2011 data and complete a further DA (with modelling if resources allow). 4. To declare an AQMA for either location when data is reliable enough to do so. 5. To deploy further diffusion tube (re-use tubes from other monitoring locations) if further actual monitoring data is required (from January Detailed Assessment Report 23

24 4 References Nitrogen Dioxide Fall off with Distance Nitrogen Dioxide Bias Adjustment Factor Spreadsheet Local Air Quality Management Technical Guidance LAQM.TG(09) Detailed Assessment Report

25 Appendices Appendix A: Raw diffusion tuba data Appendix B: QA:QC Diffusion tubes Appendix C: Diffusion Tube Bias Adjustment Factors 2011 Detailed Assessment Report 25

26 Appendix A: Raw diffusion tuba data Detailed Assessment Report

27 2011 Detailed Assessment Report 27

28 Detailed Assessment Report

29 2011 Detailed Assessment Report 29

30 Detailed Assessment Report

31 2011 Detailed Assessment Report 31

32 Detailed Assessment Report

33 2011 Detailed Assessment Report 33

34 Appendix B: QA:QC Diffusion tubes QA/QC of diffusion tube monitoring The diffusion tubes are supplied via Bureau Veritas, are analysed by Environmental Scientific Group who are a UKAS accredited laboratory. Diffusion tubes are prepared as 50% Triethanolamine (TEA) in acetone and are analysed by UV Spectrophotometry according to a documented inhouse Laboratory Method Environmental Scientific Group are classified as achieving Good performance in the Workplace Analysis Scheme for Proficiency (WASP) Report for rounds as detailed below: WASP Annual Performance Criteria for NO 2 Diffusion Tubes used in Local Air Quality Management (LAQM), 2008 onwards, and Summary of Laboratory Performance in Rounds Prepared by AEA on behalf of Defra and the Devolved Administrations. Laboratories that have demonstrated satisfactory performance in the WASP scheme for analysis of NO2 diffusion tubes, October 2008 October 2009 Laboratory Performance on basis of RPI, OLD CRITERIA, best 4 out of the 5 rounds Performance on basis of RPI, NEW CRITERIA,best 4 out of the 5 rounds Environmental Scientific Group Good Good Detailed Assessment Report

35 Appendix C: Diffusion Tube Bias Adjustment Factor Technical guidance LAQM.TG (09) and Review and Assessment Helpdesk recommends the use of a local bias adjustment factor where available and relevant to diffusion tube sites. Epping Forest District Council does not currently operate any continuous NO 2 monitoring sites; therefore a local bias adjustment factor cannot be calculated. In the absence of a local bias correction factor, the default bias correction factor for Environmental Scientifics Group analysis using the 50% TEA in acetone method has been used. This factor, calculated as 0.83 for 2010 based on 3 studies has been obtained from the defra air quality website (April 2011 release): A bias adjustment factor of 0.83 has been applied to the average of the raw diffusion tube data for the 2010 calendar year Detailed Assessment Report 35

36 In the absence of a local bias correction factor, the default bias correction factor for Environmental Scientifics Group analysis using the 50% TEA in acetone method has been used. This factor, calculated as 0.75 for 2010 based on 4 studies has been obtained from the defra air quality website (June 2011 release): A bias adjustment factor of 0.75 has also been applied to the average of the raw diffusion tube data for the 2010 calendar year Detailed Assessment Report