Jersey, Halkett Place 2000

Air Quality Monitoring, St Helier, Jersey, February to March 2000.

Brian Stacey Ray Goodwin

Air Quality Monitoring, St Helier, Jersey, February to March 2000.

Brian Stacey Ray Goodwin

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Air Quality Monitoring, St Helier, Jersey, February to March 2000. States of Jersey, Public Health Services

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AEA Technology Culham Science Centre Culham

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Brian Stacey Ray Goodwin

Brian Stacey Ken Stevenson

Executive Summary

AEA Technology's National Environmental Technology Centre (NETCEN) has been contracted by the Public Health Services and the Department of Planning and Building Services of the States of Jersey to undertake a study of air quality. This is a follow on programme of monitoring, which has been compared agai nst a similar study carried out during 1997. The monitoring assessed concentrations of vehicle related pollution at a kerbside site in St Helier. This report presents the data obtained from this monitoring survey.

In order to produce results comparable to the 1997 study the monitoring station was located in the same position as the 1997 study. The location was in Halkett Place, St Helier, next to the Indoor Market goods entrance. The immediate environment around the monitoring station

was a narrow canyon street, approximately 10 metres wide with a single lane of traffic travelling south past the site. The sampling height for the analysers was approximately 3 metres, comparable in height to similar monitoring stations in operation in the UK.

The purpose built NETCEN mobile laboratory was used for the survey, and took place from

24th February to 30th March 2000. The pollutants monitored were nitrogen dioxide and nitric oxide (NO and NO together described as NOx), carbon monoxide (CO), sulphur dioxide

(SO2) and fi2ne particulate matter (PM10). All data from the analysers were stored on datalogging equipment and subsequently retrieved at the end of the survey. Staff from the Public Health

Services of the States of Jersey visited the site on a daily basis to ensure the continued satisfactory operation of the analysers.

In general, vehicle related pollutant concentrations (NOx, CO and PM10) were found to be directly related to traffic density; highest during rush hour periods and lowest during the night. Concentrations of SO2, which is not emitted from vehicles in large quantities, were found to be very low.

Average pollutant concentrations during the monitoring period in Halkett Place were: NO 26ppb (parts per billion), NO2 21ppb, CO 1.6ppm (parts per million), SO2 5ppb and PM10 27g/m 3 (microgrammes per cubic metre). These results were found to be broadly comparable or slightly lower than those recorded during the 1997 survey.

The data from the St Helier kerbside site have also been compared to data from a number of representative sites in the UK Automatic Urban Monitoring Network, and to current UK and

EC air quality standards and guidelines. Generally, these results are comparable to roadside sites and urban background sites in London, but higher than rural and suburban sites.

Contents

1 Introduction 1 2 Site Location, Pollutants Monitored and Methodologies 1

1. SITE LOCATION 1
2. POLLUTANTS MONITORED 2
   1. Nitric Oxide and Nitrogen Dioxide, NO and NO2 2
   2. Carbon Monoxide, CO 2
   3. Sulphur Dioxide, SO2 3
   4. Particulate Matter, PM10 3
3. METHODOLOGIES 3

3 Air Quality Standards and Guidelines 4 4 Results and Discussion 5

1. PRESENTATION OF THE RESULTS 5
2. COMPARISION WITH UK MONITORING STATIONS 7
3. COMPARISON WITH STANDARDS AND GUIDELINES 10
4. PERIODS OF ELEVATED POLLUTANT CONCENTRATIONS 11

1. Sunday 27th February 2000 11
2. Friday 3rd March 2000 11
3. Saturday 4th March 2000 12

5 Conclusions 12 Appendices

1  Introduction

AEA Technology's National Environmental Technology Centre (NETCEN) has been contracted by Public Health Services and the Department of Planning and Building Services of the States of Jersey to undertake an extensive study of air quality in Jersey during 2000. Two monitoring surveys are being conducted;

• An ongoing study of nitrogen dioxide, sulphur dioxide and hydrocarbon concentrations using diffusion tube samplers and

• A month long period of measurements of vehicle related pollution at a kerbside site in St Helier.

This report presents the results of the kerbside monitoring, which took place from 24th February to 30th March 2000. This survey repeats the monitoring undertaken in Halkett Place in winter 1997. The monitoring was undertaken to investigate if changes to the traffic flow in the town, coupled with improvements in fuel technology and cleaner cars, has had any appreciable effect on air pollution levels. As with the previous study, this monitoring period was chosen for measuring kerbside concentrations, rather than the busier summer periods, because vehicle related pollution episodes are more likely to occur in the winter, during foggy or cold, calm weather. Summer pollution episodes can be dispersed more effectively by more favourable weather conditions.

Pollutants monitored were nitrogen dioxide and nitric oxide (NO2 and NO together described as NOx), carbon monoxide (CO), sulphur dioxide (SO2) and fine particulate matter (PM10). All data from the analysers were stored on data-logging equipment and subsequently retrieved at the end of the survey. Staff from the Public Health Services of the States of Jersey visited the site on a daily basis to ensure the continued reliable operation of the equiment.

Data from the survey have been ratified in accordance with the quality assurance and control procedures used in the UK Department of the Environment, Transport and the Regions Automatic Urban Monitoring Network, and are directly comparable in quality to those data. This report presents the results obtained from this survey and compares the results with a selection of UK monitoring stations and relevant air quality monitoring standards and guidelines.

2  Site Location, Pollutants

Monitored and Methodologies

1. SITE LOCATION

The monitoring station was located in Halkett Place, St Helier, next to the Indoor Market

goods entrance. This road was chosen as it is a busy thoroughfare and an area where pedestrians spend a significant amount of time. For two weeks of the monitoring period, the traffic flow past the monitoring site was assessed, and found to be in the region of 6-7000 vehicles per day. During peak times, queues of traffic may well build up past the site. It is expected that monitoring data at this location should represent the worst levels of pollution a pedestrian would encounter in the town.

The immediate environment around the monitoring station was a narrow canyon street, approximately 10 metres wide with a single lane of traffic travelling south past the site. The sampling height for the analysers was approximately 3 metres, comparable in height to similar monitoring stations in operation in the UK. The location of the monitoring station is presented in figure 1.

2. POLLUTANTS MONITORED

1. Nitric Oxide and Nitrogen Dioxide, NO and NO2

Oxides of Nitrogen, of which NO and NO are the major components, are products of combustion. NO (and small quantities of N2O2) is formed during the burning of fossil fuels in

motor vehicles, domestic heating, power generation and a wide number of other processes. NO 2 is mainly formed by subsequent reactions of NO with other compounds in the atmosphere.

Nitrogen dioxide is a respiratory irritant, and is toxic at high concentrations. It is also a major precursor in the formation of acid rain and photochemical smog. Nitric oxide is not thought to be harmful to human health at ambient concentrations, and no standards or guidelines have been set for this pollutant.

A UK government Air Quality Strategy Objective and a European Community Directive regulates concentrations of NO2 in the UK. The UK Department of the Environment,

Transport and the Regions (DETR) has defined air quality bands, which are used to describe air quality to the general public. A detailed breakdown of the guidelines and Directive are presented in Appendix 1.

2. Carbon Monoxide, CO

Carbon monoxide is formed during the inefficient burning of fuels, most notably from vehicles or poorly functioning domestic heating.

CO has a strong affinity for haemoglobin, the oxygen carrying substance in blood. Prolonged exposure to high concentrations of CO is fatal; while reduced levels of exposure can cause a number of other oxygen starvation-related health ailments.

A UK government Air Quality Strategy Objective regulates concentrations of CO in the UK. The DETR has defined air quality bands, which are used to describe air quality to the general public. These guidelines are presented in Appendix 1.

3. Sulphur Dioxide, SO2

Sulphur dioxide is formed during the combustion of fossil fuels, which have a high sulphur content, e.g. wood, coal and certain mineral oils including diesel. In recent years, emissions of SO2 have decreased in the UK with the establishment of smokeless zones and the use of cleaner fuels, to the extent that the most likely major sources of SO2 on the island will be industrial processes such as power generation and incineration.

SO2 is a respiratory irritant, which is toxic at high concentrations. It is also a major precursor in the formation of acid rain.

 A UK government Air Quality Strategy Objective and a European Community Directive regulates concentrations of SO2 in the UK. The DETR has defined air quality bands, which are used to describe air quality to the general public. A detailed breakdown of the guidelines and Directive are presented in Appendix 1.

4. Particulate Matter, PM10

Particulates in the atmosphere originate from a wide variety of sources. They take the form of dust; smoke of very small liquid or solid particles called aerosols. Particles may be either emitted directly into the atmosphere or formed subsequently by chemical reactions. PM10 particles are defined as having an average particle size of 10 microns in diameter (10 millionths of a metre), and have well documented respiratory effects on human health. There is a wide range of

human activities that produce particulate emissions, including; motor vehicles (mainly diesel), solid fuel burning, industrial processes, power stations, incinerators and construction activity.

A UK government Air Quality Strategy Objective and a European Community Directive regulates concentrations of PM10 in the UK. The DETR has defined air quality bands, which are used to describe air quality to the general public. A detailed breakdown of the guidelines and Directive are presented in Appendix 1.

3. METHODOLOGIES

The monitoring survey was carried out using Advanced Pollution Instruments (API) NOx and SO2 instruments, a Monitor Labs analyser was used for the measurements of CO, and PM10 was measured with an R&P TEOM particulate analyser. These analysers are typical of those used within the UK Automatic Urban Network. All the instruments output a voltage, which can be directly related to concentrations of the pollutant in the atmosphere.

Output voltages from the analysers were scanned every 10 seconds by a datalogger, which used these values to calculate and store 15-minute averages. The data was retrieved at the end of the survey. It was not possible to establish a telemetry link to the site, because the system used by NETCEN utilised an analogue mobile telephone. As the service for this network was disconnected on the island in 1999, it was not posssible to obtain a signal on the phone. As a result, staff from the Public Health Services of the States of Jersey visited the site on a daily basis to ensure that the analysers were functioning correctly, and reported any faults back to

NETCEN for action.

The NOx, CO and SO 2 instruments were calibrated at the beginning and end of the monitoring period. Chemical scrubbers were used to provide a clean air sample, and standard gas cylinders to provide span gas. Data from the instruments were scaled according to the instrument responses from these two point calibrations. The cylinders used were calibrated at the NETCEN Gas Standards Calibration Laboratory (GSCL). NETCEN's GSCL holds UKAS accreditation (Lab. no. 0401) for the calibration of NO, NO , SO2 and CO gas mixtures, and

for the calibration of NOx, SO2 and CO air pollution analyse2 rs on site. Using these cylinders and procedures to calibrate the analysers in Jersey ensures that the survey data are traceable to

national metrology standards.

Data from the study are accurate to within 8% for CO, 10% for SO2, and 11% for NOx. While it is not possible to reliably determine the accuracy of the particulate analyser, the precision of the instrument is within 4g/m 3.

3  Air Quality Standards and

Guidelines

In January 2000, the UK Government published a new Air Quality Strategy containing air quality objectives for four of the five pollutants measured in Halkett Place (NO2, CO, SO 2 and PM10). The objectives are based on the first EC Daughter Directive and / or the recommendations made by the Expert Panel on Air Quality Standards (EPAQS). The objectives provide policy targets by outlining what the Government considers current measures should deliver.

In the UK, EC Directives also regulate concentrations of PM10, NO 2 and SO2. The Directives set limit values, which are mandatory, and guide values, which are intended to provide increased protection to human health and the environment. The Directives require monitoring to be conducted over a whole year; limit and guide values are based on a full year of measurements. Because pollution levels vary dramatically throughout the year, it is not wholly appropriate to compare data from this program against Directives. However, for information, the limit and guide values of the Directives are summarised in Appendix 1.

The UK DETR also uses air quality bands for a number of pollutants, to describe air pollution levels (LOW, MODERATE, HIGH or VERY HIGH), on daily bulletins to the general public. These bands are summarised in Appendix 1.

4  Results and Discussion

1. PRESENTATION OF THE RESULTS

Table 1 presents a range of statistics for the pollutants measured at Halkett Place for the period 24th February to 30th March 2000. Hourly average time series graphs of these data are shown in figure 2.

For information, the units of measurement used in the report are;

NO ppb, parts per billion (109)

NO ppb, parts per billion

SO22 ppb, parts per billion

CO ppm, parts per million

PM10g/m 3, microgrammes per cubic metre

The location of the monitoring site in Halkett Place was chosen to represent the worst case scenario for any vehicle related pollution levels likely to occur on the island. Halkett Place is a narrow canyon street; because of this any pollution caused by passing vehicles is unlikely to disperse quickly,when compared to a larger road in an open environment. For areas on the island where the roads are more open or have fewer cars, air quality should be much better than at Halkett Place.

An automatic traffic count was carried out by Public Services Department during the monitoring period, to assess the flow of vehicles along Halkett Place. The results are presented in Appendix 2. The traffic count showed that average of 6900 vehicles per weekday travel past the monitoring station with a daily average, over the sampling period, of around 6600 vehicles per day.

Table 1 Basic Statistics of the Air Quality Data for Halkett Place,

24th February to 30th March 2000

During the monitoring programme, a number of significant data losses occurred. The major data gaps are summarised below:

Nine days of NOx data were rejected as a result of instrument failure. The analyser "froze" during normal operation on 29th February, and ceased to measure ambient pollution. It was not immediately obvious that the analyser was malfunctioning, which is why so much data had to be rejected during ratification. The instument was reset during a routine check by Public Health Services Staff on the 9th March.

Three days of PM10 data were lost as a result of a power failure. The analyser main fuse blew on 14th March at the same time as the power interruption. The power cut was detected at the routine check of the site on the 15th, and the power was restored, but, because of the non- standard nature of the fuse assembly, it could not be replaced by Public Health Services staff. The fuse was replaced by NETCEN on the 17th March.

In the following discussion, the data will be compared with air quality measurements at DETR national air quality monitoring network stations in the south of England. The variation of pollution levels compared to the 1997 results will also be discussed, and the measurements will be compared with current UK and EC air quality standards guidelines. Finally a number of periods of relatively elevated concentrations in Halkett Place will be reviewed.

Table 2 comparison of data obtained from the 1997 study

Comparison of the 1997 data with the 2000 data reveals that for all pollutants, maximum concentrations in 2000 were much lower than those recorded three years earlier. For CO, SO

and PM10, mean concentrations were very similar to the earlier study, while NOx averages wer2 e all lower in 2000.

These results, especially the maximum data, suggest that pollution levels were generally well suppressed, with very few classical episodes during the survey period. With the exception of NOx, the fact that average levels have remained relatively constant suggests that conditions within Halkett Place have remained quite similar in the three years since the original survey.

Weather patterns for the month generally encouraged good dispersion; either a series of low pressure systems moving through Northern Europe, bringing windy conditions to the island, or high pressure systems moving in from the South-West, bringing in relatively clean air. These weather patterns were markedly different to the 1997 survey, when conditions were generally calm and cold for a significant proportion of the monitoring study. As a result, it is difficult to reliably assess any differences in the two datasets, particularly the reduced maximum concentrations in 2000. In order to try to put the results into perspective, it will be necessary to compare the Jersey data with other sites in the UK.

2. COMPARISION WITH UK MONITORING STATIONS

Tables 3 and 4 show how data measured in Halkett Place compare with measurements made at UK national air quality monitoring stations for the corresponding period. A series of stacked timeseries plots, showing data from Halkett Place in relation to these sites, is presented in figures 3 to 6.

The locations and site descriptions of the national sites used are given below:

Lough Navar IH065545 A remote site in a clearing within a forestry

plantation (used for rural PM10 data)

Lullington Heath London A3

Leamington Spa Bristol Centre

Exeter Roadside

TQ538016 A rural site, on a high plateau 5 km from the south

coast. Immediate area is a NCC heathland. TQ193653 Adjacent to the A3 Kingston Bypass (6-lane

carriageway). Traffic flow along the bypass is

approximately 112,000 vehicles per day and is

generally fast and free flowing with little

congestion.

SP319657 An urban background site, located in a quiet cul-

de-sac close to the town centre

ST594732 Pedestrianised walkway (Lower Castle St), 43m

from a busy road (used for PM10 data in SW England).

SX929918 Located 3m from the kerb of Queen St. A canyon

street, close to a road junction. Traffic flow approx. 10,000 vehicles/day.

London Brent TQ200840 An urban background site in the grounds of a

school in North London.

A breakdown of site classifications is provided in Appendix 2.

Table 3.Comparision of Jersey data with national monitoring sites, January-February 1997 and March 2000

Table 4 ratio of average concentrations

Table 5 NO to NO2 ratios

From these data, the following general observations can be made:

1. SO2 concentrations in Jersey, while still very low, were higher than at the UK sites used for the comparison. Peak concentrations at all sites except Exeter were much lower in 2000 than the corresponding 1997 datasets.
2. PM10 concentrations in Jersey were also higher than the comparison sites, but were broadly similar to those found in London and Bristol. Peak concentrations in 2000 were higher than in 1997, for all sites except Jersey.
3. CO concentrations in Jersey were relatively low, but still higher than the comparison sites. The data was closest in values to the canyon roadside site in Exeter. Peak concentrations at all sites were lower in 2000.
4. NO 2 concentrations were lower in Jersey than at the two roadside sites, but higher than the other comparison sites. Peak concentrations were lower in 2000 at all sites except Lullington Heath.
5. Generally, average concentrations of NOx, CO and SO2 at all sites were found to be lower in 2000 than in 1997. Average PM10 concentrations at many sites were found to be slightly lower in 2000, but peak concentrations of this pollutant were generally higher – in contrast with the observations found at Halkett Place.
6. Average concentrations of PM , CO and SO in Jersey were higher than any of the other sites used for the comparison. 1A0 verage concen2 trations of NO2 in Jersey were lower than

two of the five comparison sites.

Most of these observations can be explained in terms of the differences between the environments the measurements were made in.

As has been well documented before, Halkett Place is a narrow canyon street, and as such, any pollution generated in the street is likely to disperse poorly. In contrast, the roadside site in London is much more open, allowing pollutants to disperse more easily. To confirm this, the London A3 site, despite having traffic flows 20 times higher than Halkett Place, has an average NO 2 concentration just 50% higher than the Jersey site, while average CO concentrations in London were actually lower than at Halkett Place. It would appear that, based on the results presented above, emissions of CO have not changed significantly since the 1997 survey.

Particulate concentrations at Halkett Place were found to be similar to those found at the 1997 survey, while the averages at the comparison sites had all dropped slightly since 1997. This observation may arise for a number of reasons:

1. Additional nearby sources (eg domestic fuel burning, docks, power station)
2. Differences in fuel composition (eg ultra low sulphur fuels)
3. Higher average vehicle speeds on the mainland (as vehicles are less efficient at low speeds)
4. Possibility of a higher proportion of poorly maintained vehicles on the island (as there are no formal annual MoT-type tests undertaken).

Average and peak SO2 concentrations on the island continue to be slightly higher than on the mainland. As found in 1997, there were a number of periods during the survey when SO2

levels became quite elevated, while other pollutants (excepting occasional PM10 correlation) remained largely unaffected. This result suggests that there may be a number of sources of SO2 on the island which are influencing measurements. From the evidence collected to date, the impact of these sources does not appear to have changed significantly since the initial survey in 1997.

In summary, it would appear that typical air pollution levels in Halkett Place are broadly what could be expected at a roadside location in the UK. It appears that while concentrations of CO, SO2 and PM10 were relatively low throughout the monitoring period, they were noticably higher than the UK comparison site. This could have been due to differences in meteorology, but without an extensive, long term comparison, it will not be possible to confirm this.

3. COMPARISON WITH STANDARDS AND GUIDELINES

In January 2000, the UK Government published a new Air Quality Strategy containing air quality objectives for four of the five pollutants measured in Halkett Place (NO2, CO, SO 2 and PM10). The objectives are based on the first EC Daughter Directive and / or the recommendations made by EPAQS. The objectives provide policy targets by outlining what the Government considers current measures should deliver.

In the UK, EC directives regulate ambient air quality concentrations for particulate matter, nitrogen dioxide and sulphur dioxide. In addition the DETR has defined air quality standards for PM10, NO2, SO2 and CO. NO is not thought to be harmful to health at concentrations experienced in the ambient environment and therefore there are no air quality standards or guidelines for this pollutant.

As the States of Jersey are not part of the EC, and are not governed under UK mainland law, the air quality standards and guidelines are not legally enforceable at present. However a comparison with the current guidelines provides a useful indication of the air quality on the island, providing a useful input into future air quality and traffic management strategies. A summary of these various standards and guidelines is provided in Appendix 1.

During the monitoring period the hourly mean standard for NO2 was not exceeded, although the average value of 21ppb is the same as both the DETR and EC standard value. Both the UK Strategy and EC Directives require monitoring to be undertaken over a full calendar year to reliably determine compliance. However, on the basis of these results it is unlikely that any of the limit values would be exceeded at this site. According to the DETR air quality bandings the NO2 levels for the entire monitoring period were in the LOW band.

The SO2 UK strategy and EC Directive limit and guide values were not exceeded at this site although, as with NO , a full year of monitoring is required to determine compliance. It is

unlikely that any of th2e SO2 standards or guidelines would be breached at this site.

For CO, the UK strategy concentration was not exceeded during the monitoring period.

The UK 24-hour running average information standard for PM10 was exceeded on 17 occasions during the monitoring period. The standard is widely exceeded at national monitoring sites in the UK; for example during the monitoring period the guideline was exceeded 14 times at London Brent and 17 times at Bristol Centre. This standard is used for forecasting and bulletins to the general public.

The UK and EC fixed 24-hour standard for PM10 was exceeded on 2 occasions over the monitoring period. In order for compliance to be achieved, the standard cannot be exceeded more than 35 times per year. This standard is based on gravimetric collection methods, which the TEOM analyser can underestimate by up to 30%, depending upon the enviroment being monitored. The result quoted above uses rescaled TEOM data from Jersey, to estimate the number of exceedences of this standard. As with the running 24 hour standard, it is regularly exceeded in the UK. For the same period, it was exceeded once in Bristol, twice in Brent and 5 times at A3 Roadside. A full year of monitoring is required to ensure compliance with this standard.

4. PERIODS OF ELEVATED POLLUTANT CONCENTRATIONS

1. Sunday 27th February 2000

The highest concentrations of SO2 (49ppb) were noticed during this period. Winds throughout the day were generally brisk (10 knots in the morning, reaching 30 knots by the end of the day) and south to south westerly, suggesting that the source may hae been in the region of the harbour/power station.

2. Friday 3rd March 2000

An interesting period of elevated PM10 concentrations was in the early hours of Friday March 3rd . The peak hourly averaged PM concentration was recorded at hour beginning 0700 GMT

10

at 115 g/m 3 whilst levels of other pollutants remained at background levels. Initial investigations suggested that the dust could be linked with the eruption of the Icelandic volcano Hekla the previous weekend, but subsequent modelling has also indicated that the source could have been Saharan dust storms.

3. Saturday 4th March 2000

During the evening, elevated concentrations of SO2 (28ppb), CO (5ppm) and PM10 (139

g/m 3 ) were noted. Winds were generally light (5-10 knots), northerly in origin. It is not

clear why this elevated period occurred; there is no traffic data available for this period, and winds were from a direction not usually associated with elevated pollution levels. It is possible that these elevated levels arise as a result of local activities (heating, vehicles etc.), but it is worth noting that a number of the UK monitoring locations showed similar trends in the NO2 and

CO data. It is therefore possible that these data are part of a more widespread episode.

5  Conclusions

1. AEA Technology's National Environmental Technology Centre has undertaken a short study of air pollution levels at the kerbside in Halkett Place, St. Helier , as part of a wider programme of monitoring on the island. Monitoring took place between 24th February and 30th March 2000. Concentrations of NOx, CO, SO and PM particles, were measured

2 10

using continuous automatic analysers, located in a mobile laboratory.

2. The location used in Halkett Place was the same as that used for an earlier study in 1997, and is likely to represent the worst case environment for exposure to traffic related air pollution. Approximately 6-7000 vehicles use this road every day, and because of the canyon-type environment, any pollutants emitted by vehicles are likely to be slow to disperse.
3. Concentrations of vehicle related pollutants (NOx, CO and PM10) were found to be similar to comparable sites of the UK mainland, while levels of SO2 on the island were found to be somewhat higher. Average concentrations for the survey were: NO - 21 ppb, CO - 1.6

ppm, SO - 5 ppb, PM - 27 µg m-3. Concentrations of CO, SO 2and PM were found 2 10 2 10

to be similar to those found at the site in 1997, while NO2 levels in 2000 were approximately 20% lower than in 1997. These trends are broadly reflected in the UK mainland data, where peak and average concentrations for most pollutants were also lower in 2000. Average concentrations of CO, SO2 and PM10 at Halkett Place were higher than any of the comparison sites, while levels of NO2 at the UK roadside were higher than at Halkett Place.

4. The surveys undertaken in 1997 and 2000 show how differences in weather conditions at the time of monitoring have a marked effect on measured air pollution levels. Weather during the 2000 survey generally allowed good dispersion of pollutants, contrasting with the calmer, colder, foggy conditions that were experienced more often during the 1997 survey. In order to get a complete picture of air pollution levels on the island, a long term programme of continuous monitoring should be considered.
5. Comparison of the data against air pollution standards showed that concentrations of CO and SO2 were below recommended maximum levels. Concentrations of PM10 were higher than the standard on 2 occasions, out of a permissible 35 for a year. Average NO2 concentrations for the survey were the same as the annual average standard level.

6. In order to determine full compliance with these standards, and to obtain a fuller picture of air pollution levels on the island, a longer term continuous monitoring programme should be considered, and integrated with the existing diffusion tube surveys.

Appendices

CONTENTS

Appendix 1 Air Quality Standards and Guidelines Appendix 2 Site Classifications

Appendix 3

Appendix 1

Air Quality Standards and Guidelines

CONTENTS

Appendix 2 Site Classifications

CONTENTS