Nitrogen Dioxide 2006

Air Quality Monitoring in Jersey; Diffusion Tube Surveys, 2006

Report to Public Health Services, States of Jersey

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Issue 1

Jul 2007

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Title  Air Quality Monitoring in Jersey; Diffusion Tube Surveys, 2006

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Executive Summary

AEA Energy & Environment is undertaking an ongoing programme of air quality monitoring on Jersey, on behalf of the Public Health Services Department of the States of Jersey. This report presents the results of the tenth consecutive year of monitoring, calendar year 2006 – covered by the monitoring period 3rd January 2006 to 3rd January 2007.

Diffusion tube samplers were used to monitor nitrogen dioxide (NO2) at 23 sites, and hydrocarbons at six sites. Monitoring sites were selected to measure traffic emissions and include areas likely to be affected by specific emission sources (such as petrol stations or the waste incinerator), as well as general background locations.

NO2 and hydrocarbon diffusion tubes were exposed for periods approximating to calendar months. The tubes were supplied and analysed by Harwell Scientifics Ltd, and changed by Technical Officers of Jersey's Environmental Health Section.

Annual mean NO2 concentrations at three kerbside and roadside sites in built-up areas (Weighbridge, Georgetown and La Pouquelaye) were greater than the Limit Value of 40µg m-3, set by Directive

1999/30/EEC (to be achieved by 2010), and as an Objective by the UK Air Quality Strategy, to be achieved by 31st December 2005. However, application of an adjustment factor for known diffusion

tube bias reduced the annual means at all sites to below 40µg m-3. The highest annual mean of 36 µg m-3 (after bias adjustment) was measured at the Weighbridge site.

Annual mean concentrations at urban and residential background sites were all well below 40µg m-3 in 2006.

Ambient NO2 concentrations at most of the sites in Jersey were similar to those measured in the previous year (2005); some fluctuation from year to year is to be expected, due to meteorological and other factors. Two sites (Georgetown and Weighbridge) showed slightly larger increases in 2006, and should be monitored closely to establish whether this continues.

Ambient concentrations of NO2 at some sites are showing a small but steady year on year downward trend in NO2 concentrations. However, this is not the case for all sites. The implication of this is that some kerbside sites that are currently close to the AQS Objective may remain so, unless action is taken.

The highest annual mean benzene concentration of 3.3µg m-3 was measured at Springfield Garage, where the tube is located at a petrol station. At all other sites the annual mean benzene concentration

was below 2.0µg m-3. All sites therefore met the UK Air Quality Strategy Objective of 16.25 µg m-3 for the running annual mean. All sites also met the EC 2nd Daughter Directive annual mean Limit Value of 5 µg m-3 (which is to be achieved by 2010).

Annual mean concentrations of the hydrocarbon species monitored in this study are showing a small decrease, year on year.

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Table of contents

1  Introduction  1

1. Background  1
2. Objectives  1

2  Details of Monitoring Programme  2

1. Pollutants Monitored  2
2. Hydrocarbons  2
3. Air Quality Limit Values and Objectives  3
4. Methodologies  4
5. Monitoring Sites  5
6. Calendar of Exposure Periods  8

3  Results and Discussion  9

1. Nitrogen Dioxide  9
2. Hydrocarbons  18

4  Conclusions  29 5  Recommendations  30 6  Acknowledgements  31 7  References  32

Appendices

Appendix 1  Air Quality Limit Values and Objectives Appendix 2  Monthly Mean Hydrocarbon Results

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1 Introduction

1. Background

The States of Jersey are committed to achieving standards of ambient air quality as good as, or better than, those applying in the European Union. This includes meeting EU Limit Values for a range of air pollutants, within the next 3 years. In addition, the States of Jersey have international obligations under the Climate Change Convention to reduce emissions of greenhouse gases.

AEA Energy & Environment, on behalf of the States of Jersey Public Health Services, has undertaken a further programme of air quality monitoring on the island of Jersey in 2006. This is the tenth in a series of extensive annual monitoring programmes that began in 1997.

The pollutants measured were nitrogen dioxide (NO2), and a range of hydrocarbon species (benzene, toluene, ethyl benzene and three xylene compounds), collectively termed BTEX. Average ambient concentrations were measured using passive diffusion tube samplers. NO2 was measured at 23 sites on the island, and BTEX at six sites.

This report presents the results obtained in the 2006 survey, and compares the data from Jersey with relevant air quality Limit Values, Objectives and guidelines, data from selected UK monitoring stations and previous years' monitoring programmes.

2. Objectives

This survey follows on from those in the years 1997 to 20051,2,3,4,5,6,7,8,9. The objective, as in previous surveys, was to monitor at sites where pollutant concentrations were expected to be high, and

compare these with background locations. The monitoring sites consisted of a mixture of urban and rural background sites, together with some locations where higher pollutant concentrations might be expected, such as roadside and kerbside sites, and some close to specific emission sources.

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2 Details of Monitoring Programme

1. Pollutants Monitored

2.1.1  NO2

A mixture of nitrogen dioxide (NO2) and nitric oxide (NO) is emitted by combustion processes. This mixture of oxides of nitrogen is termed NO . NO is subsequently oxidised to NO2 in the atmosphere.

NO2 is an irritant to the respiratory system,Xand can affect human health. Ambient concentrations of NO2 are likely to be highest in the most built-up areas, especially where traffic is congested, or

buildings either side of the street create a "canyon" effect, impeding the dispersion of vehicle emissions. The units used for NO2 concentration in this report are microgrammes per cubic metre

(µg m-3). Some earlier reports in this series have used parts per billion (ppb): to convert to ppb to if required, the following relationship should be used:

1 µg m-3 = 0.523 ppb for nitrogen dioxide at 293K (20C) and 1013mb.

2. Hydrocarbons

There are many sources of hydrocarbon emissions. Methane, for example, is a naturally occurring gas, while xylene compounds are synthetic and used in many applications, for example as a solvent in paint. A range of hydrocarbons is found in vehicle fuel, and occur in vehicle emissions. In most urban areas, vehicle emissions would constitute the major source of hydrocarbons, in particular benzene. Also, there is the potential that they may be released to the air from facilities where fuels are stored or handled (such as petrol stations).

A wide range of hydrocarbons is emitted from both fuel storage and handling, and from fuel combustion in vehicles. It is not easy to measure all of these hydrocarbon species (particularly the most volatile) without expensive continuous monitoring systems. However, there are four moderately volatile species, all of which may be associated with fuels and vehicle emissions, which are easy to monitor using passive samplers. These are benzene, toluene, ethyl benzene and xylene. They are not the largest constituents of petrol emissions, but due to their moderate volatility they can be monitored by diffusion tubes. Diffusion tubes are available for monitoring this group of organic compounds, and are known as "BTEX" tubes.

1. Benzene

Of the organic compounds measured in this study, benzene is the one of most concern, as it is a known human carcinogen; long-term exposure can cause leukaemia. Benzene is well known as one of the harmful compounds found in cigarette smoke, but it is also found in petrol and other liquid fuels, in small concentrations. In urban areas, the major source of benzene in ambient air is vehicle emissions.

Benzene concentrations in ambient air are generally between 1 and 15 µg m-3. In this report, concentrations of benzene are expressed in microgrammes per cubic metre (µg m-3). Some earlier

reports in the series used parts per billion (ppb): to convert to ppb to if necessary, the following relationship should be used:

1 µg m-3 = 0.307 ppb for benzene at 293K (20C) and 1013mb. (only applicable to benzene).

2. Toluene

Toluene is also found in petrol in small concentrations. Its primary use is as a solvent in paints and inks; it is also a constituent of tobacco smoke. It has been found to adversely affect human health.

Typical ambient concentrations range from trace to 3.8 µg m-3 in rural areas, up to 204 µg m-3 in

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urban areas, and higher near industrial sources. There are no recommended limits for ambient toluene concentrations, although there are occupational limits for workplace exposure10. The best estimate for

the odour threshold of toluene has been reported10 as 0.16ppm (613µg m-3). In this report, concentrations are expressed in microgrammes per cubic metre (µg m-3). Some earlier reports in the

series used parts per billion (ppb): to convert to ppb to if necessary, the following relationship should be used:

1 µg m-3 = 0.261 ppb for toluene at 293K (20C) and 1013mb. (only applicable to toluene).

(iii)ethyl benzene

Again, there are no limits for ambient concentration of ethyl benzene, and although there are occupational limits relating to workplace exposure10, as discussed in previous reports in this series,

they are several orders of magnitude higher than typical outdoor ambient concentrations.

(iv)xylene

Xylene exists in ortho (o), para (p) and meta (m) isomers. There are no limits for ambient concentration of xylenes, although (as in the case of toluene and ethyl benzene) there are occupational limits relating to workplace exposure. Xylene, like toluene, can cause odour nuisance near processes (such as vehicle paint spraying), which emit it. Its odour threshold varies according to the isomer, but the best estimate for the odour threshold of mixed xylenes is 0.016ppm (16 ppb or 70

µg m-3)11.

In this report, concentrations of ethylbenzene and xylenes are expressed in microgrammes per cubic metre (µg m-3). Some earlier reports in this series used parts per billion (ppb): to convert to ppb to if

required, the following relationship should be used:

1 µg m-3 = 0.226 ppb for ethyl benzene or xylenes at 293K (20C) and 1013mb. (applicable to ethylbenzene, m-, p- and o-xylene).

3. Air Quality Limit Values and Objectives

1. World Health Organisation

In 2000, the World Health Organisation published revised air quality guidelines12 for pollutants including NO2. These were set using currently available scientific evidence on the effects of air

pollutants on health and vegetation. The WHO guidelines are advisory only, and do not carry any mandatory status. They are summarised in Appendix 1. There are WHO guidelines for ambient NO2 (hourly and annual means) but not benzene.

2. European Community

Throughout Europe, ambient air quality is regulated by EC Directives. These set Limit Values, which are mandatory, and other requirements for the protection of human health and ecosystems. EC

Daughter Directives covering pollutants including NO and benzene 13,14 have been published in recent

2

years. The Limit Values are summarised in Appendix 1.

3. UK Air Quality Strategy

The UK Air Quality Strategy (AQS) contains standards and objectives for a range of pollutants including NO2 and benzene15. These are also summarised in Appendix 1. Only those Objectives

relating to the whole UK (as opposed to England, Wales, etc.) are applicable to Jersey, and the AQS does not at present have mandatory status in the States of Jersey.

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4. Methodologies

The survey was carried out using diffusion tubes for NO2 and BTEX. These are "passive" samplers, i.e. they work by absorbing the pollutants direct from the surrounding air and need no power supply.

Diffusion tubes for NO2 consist of a small plastic tube, approximately 7 cm long (Figure 1). During sampling, one end is open and the other closed. The closed end contains an absorbent for the gaseous species to be monitored, in this case NO2. The tube is mounted vertically with the open end at the bottom. Ambient NO2 diffuses up the tube during exposure, and is absorbed as nitrite. The average ambient pollutant concentration for the exposure period is calculated from the amount of pollutant absorbed.

BTEX diffusion tubes (also shown in Figure 1) are different in appearance to NO2 tubes. They are longer, thinner, and made of metal rather than plastic. These tubes are fitted at both ends with brass Swagelok fittings. A separate "diffusion cap" is supplied. Immediately before exposure, the Swagelok end fitting is replaced with the diffusion cap. The cap is removed after exposure, and is replaced with the Swagelok fitting. BTEX diffusion tubes are very sensitive to interference by solvents.

Diffusion tubes were prepared by Harwell Scientifics Ltd for AEA Energy & Environment, and supplied to local Technical Officers of Jersey's Public Health Services, who carried out the tube changing. The tubes were supplied in sealed condition prior to exposure. The tubes were exposed at the sites for a period of time. After exposure, the tubes were again sealed and returned to Harwell Scientifics for analysis. The year was divided into twelve exposure periods approximating to calendar months. The duration of the exposure periods varied between three and five weeks.

The diffusion tube methodologies provide data that are accurate to + 25% for NO2 and + 20% for BTEX. The limits of detection vary from month to month, but are typically 0.4 µg m-3 for NO2 and 0.2

µg m-3 for BTEX. It should be noted that tube results that are less than 10 x the limit of detection will have a higher level of uncertainty associated with them.

The Local Air Quality Management Technical Guidance LAQM.TG(03)16 states that when using diffusion tubes for indicative NO2 monitoring, correction should be made where applicable for any

systematic bias (i.e. over-read or under-read compared to the automatic chemiluminescent technique, which is the reference method for NO2). Harwell Scientifics state that their diffusion tubes typically exhibit a positive bias, and have provided a "bias adjustment factor" for 2006 of 0.75. (This applies only to NO2 diffusion tubes, not BTEX tubes, as the latter are not affected by the same sources of interference). The NO2 diffusion tube results in this report are uncorrected except where clearly specified.

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Figure 1: Diffusion Tubes for Various Pollutants

from left to right: SO2 tube (not used in this study), BTEX tube (centre), and NO2 tube.

5. Monitoring Sites

At the beginning of 2006, monitoring of NO2 was being carried out at 21 sites, the majority of which had been in use since 2000. At the end of May / beginning of June 2006, two of the urban background sites (Robin Place and L'Avenue et Dolmen) were replaced by two roadside sites at Havre des Pas and Commercial Buildings. Havre des Pas and Commercial Buildings were added to assist Traffic and Transport Services (TTS) by providing screening data for the Health Impact Assessment associated with an Energy from Waste plant proposed for La Collette. Thus, the total number of sites in operation for part or all of 2006 was 23. The total number of NO2 sites in operation at the end of 2006 remains at 21. The number of sites, and their locations, are to be reviewed for 2008.

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Table 1. NO2 Monitoring Sites in Jersey

*The Parade site was moved to its current roadside location at the end of 2000.

Kerbside: less than 1m from kerb of a busy road. Roadside: 1-5m from kerb of a busy road. Background: > 50m from the kerb of any major road.

Note: all grid references are from OS 1:25000 Leisure Map of Jersey and are given to the nearest 100m.

Figures 2a and 2b show the locations of the above sites. Figure 2b also shows the location of a new automatic monitoring site in Halkett Place, St Helier, started up at the start of 2007.

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Figure 2a. Site Locations Outside St Helier

Figure 2b. Sites in St Helier town

Key:  (both maps)  

1  Le Bas Centre  NO2, BTEX  2  Mont Felard  NO2  

3  Les Quennevais  NO2  

4  Rue Des Raisies  NO2  

5  First Tower  NO2  

6  Weighbridge  NO2  

7  Langley Park  NO2  

8  Georgetown  NO2  

9  Clos St Andre  NO2, BTEX  10  Union Street  NO2  

11  New Street  NO2  

12  Beaumont  NO2  

13  The Parade  NO2  

14  Maufant  NO2  

15  Jane Sandeman  NO2  

16  Saville Street  NO2  

17  Broad Street  NO2  

18  Beresford Street  NO2, BTEX  19  Le Pouquelaye  NO2  

20  Havre Des Pas  NO2  

21  Commercial Buildings  NO2  

22  Springfield Garage  BTEX  

23  Airport  BTEX  

24  Hansford Lane  BTEX  

25  Halkett Place  NO2, Auto  26  Robin Place  NO2  

27  L'Avenue et Dolmen  NO2  

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BTEX hydrocarbons were monitored at six sites during 2006. These are shown in Table 2. The aim was to investigate sites likely to be affected by different emission sources, and compare these with background sites. The sites at Beresford Street and Le Bas Centre are intended to monitor hydrocarbon concentrations at an urban roadside and urban background location respectively.

The Handsford Lane site was close to a paint spraying process – a potential source of hydrocarbon emissions, especially toluene and xylenes. This site replaced a similar site in Elizabeth Lane, which ceased operation when the process closed down in October 2003.

The Springfield Garage site is located by a fuel filling station, a potential sources of hydrocarbon emissions including benzene. During 2006, a vapour recovery system was fitted, which should prevent discharge of fuel vapour when their tanks are filled: however, there will still be some releases of VOCs when customers fill their cars with fuel.

The Clos St Andre site is located near the Bellozanne Valley waste incinerator, and the Airport site is located at Jersey Airport, overlooking the airfield.

Table 2. BTEX Monitoring sites

6. Calendar of Exposure Periods

The calendar of exposure periods used for the NO2 and BTEX diffusion tubes is shown below. They were intended to approximate to calendar months.

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3 Results and Discussion

1. Nitrogen Dioxide

1. Summary of NO2 Results

NO2 diffusion tube results are presented in Table 3, and Figure 3 (kerbside and roadside sites), Figure 4 (background sites), and Figure 5 (residential and rural sites). Individual monthly mean NO2 results

ranged from 2.6 µg m-3 (in October at the residential background Les Quennevais site), to 54.3 µg m-3 (in April at the kerbside Weighbridge site).

There were two occasions when no valid value was obtained: no tube was returned from Beresford Street in August, and Langley Park in September.

Two unusually low values were recorded: at Les Quennevais, the monthly mean for October was 2.6 µg m-3, unusually low compared to typical results for the site. However, in the absence of any evidence

to suggest that it is spurious, the value has not been rejected. Also, the September result from Clos St Andre was below the detection limit (<0.04µg m-3). This is suspiciously low and the result has been

disregarded as most likely a faulty tube.

Annual mean NO concentrations ranged from 6.3 µg m-3 (at the rural Rue des Raisies site ) to 48.2 µg m-3 at the Weig[2]hbridge site. The latter is a location in the centre of St Helier which is used as a central stopping point for buses.

2. Comparison with NO2 Guidelines, Limit Values, and Objectives

Limit Values, AQS Objectives and WHO guidelines for NO2 are shown in Appendix 1. These are based on the hourly and annual means. Because of the long sampling period of diffusion tubes, it is only possible to compare the results from this study against limits relating to the annual mean.

The WHO non-mandatory guideline12 for NO2 is that the annual mean should not exceed 40 µg m-3. The EC 1st Daughter Directive13  contains Limit Values for NO as follows:

2

200 µg m-3 as an hourly mean, not to be exceeded more than 18 times per calendar year. To be

achieved by 1 January 2010.

40 µg m-3 as an annual mean, for protection of human health. To be achieved by 1 January 2010. There is also a limit for annual mean total oxides of nitrogen (NO ), of 30 µg m-3, for protection of

vegetation (relevant in rural areas).  X

The UK Air Quality Strategy contains Objectives for NO2, which are very similar to the EC Daughter Directive limits above: the only differences being the more stringent dates by which they must be attained (31 December 2005).

Annual mean NO2 at three sites exceeded 40µg m-3; these were Weighbridge, Georgetown and La Pouquelaye. All three are urban kerbside sites that have recorded relatively high annual mean NO2 concentrations in previous years of this survey.

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Applying this factor reduces the annual means at all sites to below the AQS Objective of 40µg m-3. The highest annual mean (at Weighbridge) is reduced from 48.2 µg m-3 (unadjusted) to 36.2 µg m-3

(adjusted). Application of the bias adjustment factor reduced the annual mean NO2 concentrations at the 12 background sites to well below 40 µg m-3. All Jersey sites met the AQS Objective for annual

mean NO2.

The 30µg m-3 limit for protection of vegetation is only applicable at the one rural background site, Rue des Raisies; the annual mean NO2 concentration at this site was well within the limit.

Table 3. NO2 Diffusion Tube Results 2006, Jersey. Concentrations in µg m-3 .

K = Kerbside, R = Roadside, UB = Urban Background, Res B = Residential Background, Rur B = Rural Background. TM = tube missing, bdl = below detection limit. Annual mean concentrations greater than 40µg m-3 highlighted in bold.

Figure 3. Monthly Mean Nitrogen Dioxide Concentrations at Roadside and Kerbside Sites, 2006

60

50

40

First Tower Weighbridge Georgetown Beaumont

30

The Parade

Broad Street

La Pouquelaye Havre des Pas Commercial Buildings

20

10

0

Exposure period

Figure 4. Monthly Mean Nitrogen Dioxide Concentrations at Urban Background Sites, 2006

Le Bas Centre L'Avenue et Dolmen Robin Place

Jane Sandeman Saville Street Beresford Street

Exposure period

 Figure 5. Monthly Mean Nitrogen Dioxide Concentrations at Residential and Rural Background Sites, 2006

35 30 25 20 15 10

Mont Felard

Les Quennevais Langley Park Clos St.Andre Maufant

Rue Des Raisies

5 0

Exposure period

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3. Comparison with UK NO2 data

Table 4 shows annual mean NO2 concentrations measured at a selection of UK air quality monitoring stations using automatic (chemiluminescent) NO2 analysers. The automatic data have been fully ratified. The sites used for comparison are as follows:

Exeter Roadside – a roadside site in the centre of Exeter, Devon.

Brighton Roadside – a roadside site in the coastal city of Brighton, Sussex.

Brighton Preston Park – an urban background site in Brighton.

Southend on Sea – an urban background site in the coastal town of Southend, Essex.

Lullington Heath - a rural site on the South Coast of England near the town of Eastbourne.

Harwell - a rural site in the south of England, within 10km of a power station.

Table 4 - Comparison of NO2 in Jersey with UK Automatic Sites

The bias adjusted annual mean NO concentrations measured at the kerbside and roadside sites in Jersey ranged from 17 to 36µg m-3. 2The annual means at Exeter Roadside and Brighton Roadside

were slightly higher than these. The Jersey urban background sites had (bias adjusted) annual mean NO concentrations ranging from 10 µg m-3 to 26 µg m-3; the urban background sites in Southend and

2

Brighton were therefore within this range. Residential background sites well outside Jersey's larger towns (e.g. Les Quennevais, Clos St Andre, Maufant) had bias-adjusted annual mean NO2 ranging

from 7 µg m-3 to 18 µg m-3, and thus were more comparable with rural sites such as Lullington Heath and Harwell. The bias-adjusted annual mean of 4.7 µg m-3 at the Jersey rural background site, Rue

des Raisies, was considerably lower than that measured at either Harwell or Lullington Heath.

4. Comparison with Previous Years' Nitrogen Dioxide Results

Annual mean NO2 concentrations for 2006, at the majority of sites, were within 2µg m-3 of the previous year's annual mean – some higher and some lower than last year. The exceptions were Weighbridge,

which recorded an increase of 4 µg m-3, and Georgetown, which recorded an increase of 5 µg m-3. Some degree of fluctuation in annual mean concentrations is expected, due to meteorology.

Long-term trends were also investigated. The majority of the NO2 monitoring sites in this survey have been in operation since 2000. However, the survey includes three longer-running sites, which were part of the former UK Nitrogen Dioxide Network and have been in operation since 1993. These are Beaumont (kerbside), Jane Sandeman Road (urban residential) and Maufant (residential background, rural location).

Table 5 and Figure 6 show annual mean NO2 concentrations for all sites in the kerbside and roadside, urban background and residential background categories. Also shown are annual means from 1993 onwards for the three long-running sites. These data are not adjusted for diffusion tube bias; prior to 2002 there was no reliable information on which to carry out bias adjustment, so for consistency, uncorrected data are used in this section.

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Of the three long-running Jersey sites, only the residential background Jane Sandeman road site

shows a small but consistent downward trend. In the case of the Maufant site, NO2 concentrations are

lower than they were in the early 1990s, but there is no clear trend in recent years. Nor is there any

clear trend for the kerbside Beaumont site.

The average NO2 concentration for all roadside and kerbside sites appears to show a small but consistent downward trend since 2000, with a particularly marked reduction since 2003 (which was a notably high year). There is no clear trend in the mean of all urban background sites, or all residential background sites.

Figure 6. Trends in Annual Mean NO2 Concentrations (not corrected for diffusion tube bias).

Maufant (Rural Bkgd.)

Jane Sandeman (Res. Bkgd.)

All Residential Background 50 All Urban Background

45 All Kerbside & Roadside

Beaumont (Kerbside)

40

35

30

25

20

15

10

5 0

Year

Trends were investigated at each individual site. Many of the kerbside and roadside sites showed small but consistent downward trends (two exceptions being Weighbridge and Broad Street). There is some indication of increasing levels at two non-roadside sites, Clos St Andre and L'Avenue et Dolmen). At the many sites at which there is no clear downward trend, sites currently at risk of exceeding AQS objectives or EC limit are likely to remain so.

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Table 5 Annual mean NO2 concentrations, µg m-3 (not bias adjusted)

Site  1993  1994  1995  1996  1997  1998  1999  2000  2001  2002  2003  2004  2005  2006 Beaumont  44  25  24  -  38  40  44  46  42  48  39  42  39

(Kerbside)

Jane Sandeman  21  19  21  21  -  17  17  15  17  17  19  16  15  14

(Res. Bkgd.)

Maufant (Rural  17  15  13  11  -  10  11  10  8  10  11  9  9  10

Bkgd.)

All Kerbside &  -  -  -  -  -  -  -  43  43  43  44  38  37  36

Roadside

All Urban  -  -  -  -  -  -  -  27  27  27  30  25  25  26 Background

All Residential  -  -  -  -  -  -  -  16  16  17  19  15  16  16

Background

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2. Hydrocarbons

1. Summary of Hydrocarbon Results

Results of the hydrocarbon survey for the six sites are shown in Appendix 2, Tables A2.1 to A2.6 respectively. Graphical representations are shown in Figures 7 to 12.

A summary of annual average hydrocarbon concentrations is shown in Table 6. Some measurements, particularly at the Airport site, were below the detection limit. By convention, when calculating annual averages and plotting graphs, such results are assumed to be half the detection limit.

Table 6. Summary of Average Hydrocarbon Concentrations, Jersey, 2006

All sites achieved full data capture, except the following:

1. Beresford Street: the March tube recorded values below the detection limit for all BTEX compounds. This atypically low result was rejected as spurious, being more likely to result from a faulty diffusion tube than genuinely low results at this site.
2. Beresford Street: the September hydrocarbon tube went missing from the site, as did the NO2 tube for the same month.
3. the Airport, where the January tube could not be changed and was left in place fortwo months. The two-month average obtained was rejected as unreliable.

The Springfield Garage monitoring site continues to record the highest annual mean concentrations of all five BTEX compounds, as it typically has in previous years. The Handsford Lane site (near a paint spraying process) has in previous years also measured slightly higher levels of toluene, ethylbenzene and xylenes than most of the other sites. However, in 2006 levels of these compounds were comparable with Beresford Street and Le Bas Centre. Ambient concentrations of toluene decreased

substantially in 2005, and have remained less than 5µgm-3 in 2006. The Airport site, which is in rural surroundings, recorded the lowest annual mean concentrations of most of the BTEX hydrocarbons. However, relatively high levels of ethylbenzene and xylenes were measured in September.

Benzene concentrations at Handsford Lane were no higher than those at Beresford Street or Le Bas; the nearby paint spraying process is not a significant source of benzene.

Figure 7. Monthly mean hydrocarbon concentrations at Beresford Street, 2006

12.0 10.0

8.0 6.0 4.0 2.0 0.0

benzene toluene

ethyl benzene m,p -xylene o-xylene

Start Date of Exposure period

Figure 8. Monthly mean hydrocarbon concentrations at Le Bas Centre, 2006

8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0

benzene toluene

ethyl benzene m,p -xylene o-xylene

0.0

Start Date of Exposure period

Figure 9. Monthly mean hydrocarbon concentrations at Handsford Lane, 2006

9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.0

benzene toluene

ethyl benzene m,p -xylene o-xylene

Start Date of Exposure period

Figure 10. Monthly mean hydrocarbon concentrations at Springfield Garage, 2006

35.0 30.0 25.0 20.0 15.0 10.0

benzene toluene

ethyl benzene m,p -xylene o-xylene

5.0 0.0

Start Date of Exposure period

Figure 11. Monthly mean hydrocarbon concentrations at Clos St Andre, 2006

3.5 3.0 2.5 2.0 1.5

benzene toluene

ethyl benzene m,p -xylene o-xylene

1.0 0.5 0.0

Start Date of Exposure period

Figure 12. Monthly mean hydrocarbon concentrations at the Airport, 2006

4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0

benzene toluene

ethyl benzene m,p -xylene o-xylene

Start Date of Exposure Period

2. Comparison With Limit Values and Objectives

Of the hydrocarbon species monitored, only benzene is the subject of any applicable air quality standards. The UK Air Quality Strategy sets the following objectives for benzene:

16.25µg m-3 (for the running annual mean), to be achieved by 31 December 2003

3.25 µg m-3 (for the calendar year mean), to be achieved by 31 December 2010.

These are applicable to the whole UK. Although they are not at present mandatory in Jersey, the States of Jersey are committed to meeting air quality standards at least as stringent as those applying throughout the EU.

The annual mean benzene concentration (which can be considered a good indicator of the running annual mean) did not exceed 16.25µg m-3 at any of the Jersey sites. The calendar year mean was less

than the 2010 objective of 3.25 µg m-3, at all sites except Springfield Garage.

The EC 2nd Daughter Directive14 sets a limit of 5µg m-3 for annual mean benzene, to be achieved by 2010. All sites met this limit.

3. Comparison with UK Benzene Data

Benzene was measured using pumped-tube samplers at a large UK-wide network of 30 UK sites in 2006. Annual mean concentrations ranged from 0.7 µg m-3 (at Coventry's Memorial Park) to 2.17

µg m-3 (at Birmingham Roadside), but were typically in the range of 1-2 µg m-3 at most urban sites.

Table 7 compares benzene data from the Jersey sites, with that from a selection of UK monitoring stations, located in cities on the south coast of England. The sites used for comparison are:

Bournemouth – an urban background site in a coastal town.

Hove Roadside – a roadside site in the coastal town of Hove, near Brighton, Sussex.

Plymouth – an urban background site in the coastal city of Plymouth, Devon

Portsmouth – an urban background site in Portsmouth , Hampshire

Southampton – a roadside site in the city of Southampton

Southend on Sea – an urban background site in Southend, Essex.

Table 7. Comparison with Benzene Concentrations at Other UK Sites, Calendar Year 2006 (with data capture in brackets).

n/a = not available.

The annual mean benzene concentration at Springfield Garage (where fuels are stored) was higher than any of the other Jersey or UK Network sites, including the roadside sites at Southampton and Hove. In previous years it has been reported that benzene levels at Clos St Andre and the Airport were lower than typical UK urban levels; however, UK urban levels are decreasing and this is no longer the case. However, it should be noted that the UK measurements are made with a different technique (pumped tube samplers) than the BTEX tubes used in the Jersey study, so this observed difference may be due at least in part to the difference in measurement techniques.

(Toluene, ethlybenzene and xylenes are no longer part of the UK monitoring programme).

4. Comparison with Previous Years' Hydrocarbon Results

Table 8 shows annual mean hydrocarbon concentrations for these sites, for years 1997 – 2006. Figures 13 to 17 illustrate how annual mean concentrations of these hydrocarbons have changed over the years of monitoring.

As well as the six sites currently in operation, Table 8 also shows previous years' results from a site at Elizabeth Lane. This site was located close to a paint spraying process: when the process closed down, monitoring was re-located to Handsford Lane, which is close to another similar process.

Annual mean levels of benzene at all sites were very slightly higher in 2006 than in the previous year; this is in contrast to the UK, where annual mean concentrations of this pollutant were typically lower than the previous year.

Annual mean toluene concentrations at all sites except Handsford Lane were slightly lower in 2006 compared to 2005. Annual mean concentrations of ethylbenzene and xylenes were lower compared to 2005 at all sites except the Airport. However, it is important to remember that pollutant concentrations are expected to show considerable year-to-year variation, due to meteorological and other factors. Year-to year changes are therefore of less importance than the observation of long-term trends, which are discussed below.

Table 8. Comparison of Hydrocarbon Concentrations, Jersey, 1997 - 2006. benzene,  toluene,  ethylbenzene m+p  o-xylene,

xylene,

µg m-3 µg m-3 µg m-3 µg m-3 µg m-3

Beresford Street

Le Bas Centre

Elizabeth Lane

1997  6.2  16.9  6.2  7.5  9.7

1998  6.2  19.2  3.1  7.1  3.5

1999  3.3  12.6  2.2  5.3  2.7

2000  2.3  12.6  3.1  8.0  2.7

2001  2.3  15.7  3.1  8.8  3.5

2002  1.6  11.1  2.2  6.2  1.8

2003  2.0  11.9  2.2  6.2  2.2 Springfield Garage

Table 8. Comparison of Hydrocarbon Concentrations, -continued : Jersey, 1997 - 2006.

Figure 13. Trends in Benzene Concentration

 Handsford Lane Airport

30.0 Clos St Andre Elizabeth Lane

Le Bas Centre 25.0

Beresford Street

Springfield Garage 20.0

15.0

10.0

5.0

0.0

19971998 1999 2000 2001 2002

2003 2004

2005 2006

Figure 14. Trends in Toluene Concentration

 Handsford Lane 50.0

Airport

45.0

 Clos St Andre

40.0 Elizabeth Lane

35.0 Le Bas Centre

30.0 Beresford Street

25.0 Springfield Garage 20.0

15.0 10.0

5.0 0.0

Year

Figure 15. Trends in Ethylbenzene Concentration

 Handsford Lane Airport

 Clos St Andre

14.0 Beresford Street

12.0 Le Bas Centre Elizabeth Lane

10.0 Springfield Garage 8.0

6.0

4.0

2.0

0.0

Year

Figure 16. Trends in m+p- Xylene Concentration

 Handsford Lane Airport

 Clos St Andre 25.0

Beresford Street Le Bas Centre

20.0 Elizabeth Lane Springfield Garage

15.0

10.0

5.0

0.0

1997 1998 1999 2Y00e0ar2001 2002 2003 2004 2005 2006

Figure 17. Trends in o-Xylene Concentration

 Handsford Lane Airport

10.0

 Clos St Andre

9.0 Beresford Street

8.0 Le Bas Centre

7.0 Elizabeth Lane Springfield Garage

6.0

5.0

4.0

3.0

2.0

1.0

0.0

1997 1998 1999 2000

2001 2002 2003 2004

Year 2005 2006

Most hydrocarbon species appear to have decreased over the ten years of monitoring, being in most cases lower now than in the late 1990s.

Benzene showed a marked drop in 2000: this is due to the maximum permitted benzene

content of petrol sold in the UK being reduced from 2% in unleaded (5% in super unleaded), to 1% as of 1st January 2000. Concentrations have continued to fall slightly year on year.

Toluene concentrations show a small but steady downward trend over the 10 years of the

survey (1997-2006).

Ethylbenzene concentrations have also generally decreased, despite an unexplained increase

in 2004.

Concentrations of m+p xylene, and of o-xylene, are also now generally lower than in the early

years of the survey.

4 Conclusions

AEA Energy & Environment has undertaken a year-long diffusion tube monitoring study in Jersey during 2006, on behalf of the States of Jersey Public Health. This monitoring study has now been undertaken for ten consecutive years.

Diffusion tubes were used to monitor NO2 at 23 sites.

Hydrocarbons (benzene, toluene, ethyl benzene and xylenes, collectively termed BTEX) were measured at 6 sites.

The sites were located at a range of different locations on the island, many of which have been in operation since 2000, and some since 1997.

Two new kerbside sites were set up for monitoring of NO2. These were located at Commercial Buildings and Havre des Pas. They replaced two urban background sites (Robin Place and L'Avenue et Dolmen) which were no longer required.

NO2 results

Annual mean (uncorrected) NO2 concentrations at two kerbside sites (Weighbridge, Georgetown and La Pouqulaye) were above the EC Directive Limit Value and AQS Objective of 40µg m-3.

Applying the analytical laboratory's recommended correction factor for diffusion tube bias to these annual mean results reduced all of them to below 40µg m-3. However, given the uncertainty inherent in

diffusion tube measurements, together with the lack of any clear downward trend in NO2 concentrations on Jersey, it is possible that some kerbside and roadside sites will continue to be close to the limit value in future years.

Annual mean NO2 concentrations at all urban, residential and rural background sites were all below the EC Limit Value – in most cases by a substantial margin.

Annual mean NO2 concentrations at the monitoring sites were in most cases within of 4 µg m-3 of those measured the previous year, the exceptions being Georgetown and Weighbridge which

recorded a larger increase.

Of the three long-running sites, which have operated since 1993 as part of the UK NO2 Network., only one (Jane Sandeman Rd) shows a clear downward trend in NO2 concentration.

There is a small but consistent downward trend in the average annual mean NO2 concentrations for all kerbside and roadside sites, but not for all urban background sites, or all residential sites.

Trends were briefly investigated for all sites: at most sites there was a slight downward trend or no clear trend. However, levels may possibly be increasing at Clos St Andre and L'Avenue et Dolmen.

One implication of the apparent relative stability of NO concentrations, is that sites currently close to the Limit Value and AQS Objective of 40µg m-3 for annu2al mean NO2 concentration may remain so,