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The Air Quality Standards (Scotland) Regulations 2007

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Regulation 6

SCHEDULE 1Air quality standards

PART 1Limit values for Group A pollutants

Benzene

Averaging periodLimit valueAttainment date
Limit value for the protection of human healthCalendar year5 μg/m31st January 2010

Carbon monoxide

For the purposes of this table, the maximum daily 8-hour mean concentration shall be selected by examining 8-hour running averages, calculated from hourly data and updated each hour. Each 8 hour average so calculated shall be assigned to the day on which it ends, i.e. the first calculation period for any one day shall be the period from 17:00 on the previous day to 01:00 on that day; the last calculation period for any one day shall be the period from 16:00 to 24:00 on that day.

Averaging periodLimit value
Limit value for the protection of human healthMaximum daily 8-hour mean10 mg/m3

Lead

Averaging periodLimit value
Annual limit value for the protection of human healthCalendar year0.5 μg/m3

Nitrogen dioxide (NO2) and oxides of nitrogen (NOx)

Averaging periodLimit valueAttainment date
Hourly limit value for the protection of human health1 hour200 μg/m3 NO2, not to be exceeded more than 18 times a calendar year1st January 2010
Annual limit value for the protection of human healthCalendar year40 μg/m3 NO21st January 2010
Annual limit value for the protection of vegetationCalendar year30 μg/m3 NOx

PM10

Averaging periodLimit value
24-hour limit value for the protection of human health24 hours50 μg/m3 PM10, not to be exceeded more than 35 times a calendar year
Annual limit value for the protection of human healthCalendar year40 μg/m3 PM10

Sulphur dioxide

Averaging periodLimit value
Hourly limit value for the protection of human health1 hour350 μg/m3, not to be exceeded more than 24 times a calendar year
Daily limit value for the protection of human health24 hours125 μg/m3, not to be exceeded more than 3 times a calendar year
Limit value for the protection of ecosystemsCalendar year and winter (1st October to 31st March)20 μg/m3

PART 2Margins of tolerance for benzene and nitrogen dioxide

Start of period during which the margin appliesEnd of period during which the margin appliesBenzeneNitrogen dioxide (hourly limit value for the protection of human health)Nitrogen dioxide (annual limit value for the protection of human health)
Coming into force of these Regulations31st December 20073 μg/m330 μg/m36 μg/m3
1st January 200831st December 20082 μg/m320 μg/m34 μg/m3
1st January 200931st December 20091 μg/m310 μg/m32 μg/m3

PART 3Target values for Group B pollutants

1.  The target values in the table at paragraph 2 in each case relate to the total content of the relevant pollutant in the PM10 fraction averaged over one calendar year.

2.  The attainment date for each of these target values is 31st December 2012.

PollutantTarget value
Arsenic6 ng/m3
Benzo(a)pyrene1 ng/m3
Cadmium5 ng/m3
Nickel20 ng/m3

PART 4Target values and long-term objectives for ozone

3.  In this Part–

(a)all values shall be expressed in μg/m3;

(b)the volume shall be standardised at the following conditions of temperature and pressure: 293K and 101.3kPa;

(c)the time shall be specified in Central European Time;

(d)“AOT40” (expressed in (μg/m3).hours) means the sum of the difference between hourly concentrations greater than 80 μg/m3 (which equals 40 parts per billion) and 80 μg/m3 over a given period using only the 1 hour values measured between 08:00 and 20:00 Central European Time each day; and

(e)in order to be valid, the annual data on exceedances used to check compliance with the target values and long-term objectives below must meet the criteria set out in Part 2 of Schedule 12.

Target values

The attainment date for the target values set out in the following table is 2010, with compliance assessed over the periods indicated for each target value in the table.

ParameterTarget value and assessment for 2010(1)
(1)

Compliance with target values will be assessed as of this value. That is, 2010 will be the first year the data for which is used in calculating compliance over three or five years, as appropriate.

(2)

The maximum daily 8-hour mean concentration shall be selected by examining 8-hour running averages, calculated from hourly data and updated each hour. Each 8-hour average so calculated shall be assigned to the day on which it ends, that is, the first calculation period for any one day shall be the period from 17:00 on the previous day to 01:00 on that day; the last calculation period for any one day will be the period from 16:00 to 24:00 on the day.

(3)

If the three or five year averages cannot be determined on the basis of a full and consecutive set of annual data, the minimum annual data required for checking compliance with the target values shall be as follows: (i) for the target value for the protection of human health, valid data for one year; and (ii) for the target value for the protection of vegetation, valid data for three years.

Target value for the protection of human healthMaximum daily 8-hour mean(2)120 μg/m3 not to be exceeded on more than 25 days per calendar year averaged over three years(3)
Target value for the protection of vegetationAOT 40, calculated from 1 hour values from May to July18,000 μg/m3.hour averaged over five years(3)

Long-term objectives

ParameterLong-term objective
Long-term objective for the protection of human healthMaximum daily 8-hour mean within a calendar year120 μg/m3
Long-term objective for the protection of vegetationAOT40, calculated from 1 h values from May to July6,000 μg/m3.h

Regulation 8(4)

SCHEDULE 2Information to be included in an Improvement Plan

1.  Localisation of excess pollution–

(a)region;

(b)city (map); and

(c)measuring station (map, geographical co ordinates).

2.  General information–

(a)type of zone (city, industrial or rural area);

(b)estimate of the polluted area (km2) and of the population exposed to the pollution;

(c)useful climatic data;

(d)relevant data on topography; and

(e)sufficient information on the type of targets requiring protection in the zone.

3.  Responsible authorities (names and addresses of persons responsible for the development and implementation of improvement plans).

4.  Nature and assessment of pollution–

(a)concentrations observed over previous years (before the implementation of the improvement measures);

(b)concentrations measured since the beginning of the project; and

(c)techniques used for the assessment.

5.  Origin of pollution–

(a)list of the main emission sources responsible for pollution (map);

(b)total quantity of emissions from these sources (tonnes/year); and

(c)information on pollution imported from other regions.

6.  Analysis of the situation–

(a)details of those factors responsible for the excess (transport, including cross-border transport, formation); and

(b)details of possible measures for improvement of air quality.

7.  Details of those measures or projects for improvements which existed prior to 21st November 1996–

(a)local, regional, national, international measures; and

(b)observed effects of these measures.

8.  Details of those measures or projects adopted with a view to reducing pollution following 21st November 1996–

(a)listing and description of all the measures set out in the project;

(b)timetable for implementation; and

(c)estimate of the improvement of air quality planned and of the expected time required to attain these objectives.

9.  Details of the measures or projects planned or being researched for the long term.

10.  List of the publications, documents, and work used to supplement information required by this Schedule.

Regulation 11(7)

SCHEDULE 3Alert and information thresholds

PART 1Alert thresholds for nitrogen dioxide and sulphur dioxide

Nitrogen dioxide400 μg/m3 measured over three consecutive hours at locations representative of air quality over at least 100 km2 or an entire zone or agglomeration, whichever is the smaller
Sulphur dioxide500 μg/m3 measured over three consecutive hours at locations representative of air quality over at least 100 km2 or an entire zone or agglomeration, whichever is the smaller

PART 2Alert and information thresholds for ozone

ParameterThreshold
(1)

For the purposes of regulation 11 (action plans), exceedance of the 1 hour average in respect of the alert threshold is to be measured or predicted for three consecutive hours.

Alert threshold1 hour average(1)240 μg/m3
Information threshold1 hour average180 μg/m3

Regulation 2(1) Regulation 13(6)

SCHEDULE 4Assessment thresholds

PART 1Assessment thresholds for Group A pollutants

Benzene

Annual average
Upper assessment threshold70% of limit value (3.5 μg/m3)
Lower assessment threshold40% of limit value (2 μg/m3)

Carbon monoxide

Eight-hour average
Upper assessment threshold70% of limit value (7 mg/m3)
Lower assessment threshold50% of limit value (5 mg/m3)

Lead

Annual average
Upper assessment threshold70% of limit value (0.35 μg/m3)
Lower assessment threshold50% of limit value (0.25 μg/m3)

Nitrogen dioxide (NO2) and oxides of nitrogen (NOx)

Hourly limit value for the protection of human health (NO2 )Annual limit value for the protection of human health (NO2)Annual limit value for the protection of vegetation (NOx)
Upper assessment threshold70% of limit value (140 μg/m3), not to be exceeded more than 18 times in any calendar year80% of limit value (32 μg/m3)80% of limit value (24 μg/m3)
Lower assessment threshold50% of limit value (100 μg/m3), not to be exceeded more than 18 times in any calendar year65% of limit value (26 μg/m3)65% of limit value (19.5 μg/m3)

PM10

24-hour averageAnnual average
Upper assessment threshold60% of limit value (30 μg/m3), not to be exceeded more than 7 times in any calendar year70% of limit value (14 μg/m3)
Lower assessment threshold40% of limit value (20 μg/m3), not to be exceeded more than 7 times in any calendar year50% of limit value (10 μg/m3)

Sulphur dioxide

Health protectionEcosystem protection
Upper assessment threshold60% of 24-hour limit value (75 μg/m3), not to be exceeded more than 3 times in any calendar year60% of winter limit value (12 μg/m3)
Lower assessment threshold40% of 24-hour limit value (50 μg/m3), not to be exceeded more than 3 times in any calendar year40% of winter limit value (8 μg/m3)

PART 2Assessment thresholds for Group B pollutants

Arsenic

Upper assessment threshold60% of target value (3.6 ng/m3)
Lower assessment threshold40% of target value (2.4 ng/m3)

Benzo(a)pyrene

Upper assessment threshold60% of target value (0.6 ng/m3)
Lower assessment threshold40% of target value (0.4 ng/m3)

Cadmium

Upper assessment threshold60% of target value (3 ng/m3)
Lower assessment threshold40% of target value (2 ng/m3)

Nickel

Upper assessment threshold70% of target value (14 ng/m3)
Lower assessment threshold50% of target value (10 ng/m3)

PART 3Determination of representative concentrations

1.  The representative concentration of the relevant pollutant shall be determined on the basis of concentrations during the previous five years where sufficient data are available. The upper assessment threshold will be deemed to have been exceeded if it has been exceeded during at least three separate years out of the previous five years. The lower assessment threshold will be deemed to have been equalled or exceeded if it has been equalled or exceeded during at least three separate years out of the previous five years.

2.  Where fewer than five years' data are available, measurement campaigns of short duration during the period of the year and at locations likely to be typical of the highest concentrations may be combined with results obtained from emission inventories and modelling to determine exceedances of the upper and lower assessment thresholds.

Regulation 15(1), (4), (5) and (7)

SCHEDULE 5Minimum number of sampling points

PART 1Group A pollutants: human health based limit values and alert thresholds

1.  This Part sets out the minimum number of sampling points for fixed measurement of Group A pollutants to assess compliance with limit values for the protection of human health and alert thresholds in zones where fixed measurement is the sole source of information.

Diffuse sources

Population of zone (thousands)If concentrations exceed the upper assessment threshold(1)If maximum concentrations are between the upper and lower assessment thresholdsFor nitrogen dioxide and sulphur dioxide in agglomerations where maximum concentrations are below the lower assessment thresholds
(1)

For NO2 and PM10 to include at least one urban-background station and one traffic-orientated station; this requirement shall also apply to benzene and carbon monoxide provided that it does not increase the number of sampling points.

0–24911not applicable
250–499211
500–749211
750–999311
1,000–1,499421
1,500–1,999521
2,000–2,749632
2,750–3,749732
3,750–4,749842
4,750–5,999942
6,000 or more1053

Point sources

2.  For the assessment of pollution in the vicinity of point sources, the number of sampling points for fixed measurement shall be calculated taking into account emission densities, the likely distribution patterns of ambient-air pollution and the potential exposure of the population.

PART 2Group A pollutants: limit values for the protection of ecosystems or vegetation

3.  The following table sets out the minimum number of sampling points for fixed measurements to assess compliance with limit values for the protection of ecosystems or vegetation in zones other than agglomerations.

If maximum concentrations exceed the upper assessment thresholdIf maximum concentrations are between the upper and lower assessment thresholds
1 station every 20,000 km21 station every 40,000 km2

4.  In island zones the number of sampling points for fixed measurement shall be calculated taking into account the likely distribution patterns of ambient-air pollution and the potential exposure of ecosystems or vegetation.

PART 3Group B pollutants

5.  This Part sets out the minimum number of sampling points for fixed measurement of Group B pollutants to assess compliance with target values for the protection of human health in zones where fixed measurement is the sole source of information.

Diffuse sources

Population of zone (thousands)If maximum concentrations exceed the upper assessment threshold(1)If maximum concentrations are between the upper and lower assessment thresholds
Arsenic, Cadmium, NickelBenzo(a)pyreneArsenic, Cadmium, NickelBenzo(a)pyrene
(1)

To include at least one urban-background station and for benzo(a)pyrene also one traffic-oriented station provided this does not increase the number of sampling points.

0–7491111
750–19992211
2000–37492311
3750–47493422
4750–59994522
≥60005522

Point sources

6.  For the assessment of pollution in the vicinity of point sources, the number of sampling points for fixed measurement shall be determined taking into account emission densities, the likely distribution patterns of ambient air pollution and potential exposure of the population. The sampling points should shall be sited such that the application of the measures referred to at regulation 7(2)(b) can be monitored.

PART 4Ozone

7.  Except in so far as otherwise provided by regulation 15(5) or (6), the minimum number of sampling points for fixed continuous measurement to assess air quality in view of compliance with the target values, long-term objectives and information and alert thresholds where continuous measurement is the sole source of information is set out in the following table below.

Population of zone (thousands)Agglomerations (urban and suburban)(1)Other zones (suburban and rural)(1)Rural background
(1)

At least 1 station in suburban areas, where the highest exposure of the population is likely to occur. In agglomerations at least 50% of the stations should shall be located in suburban areas.

(2)

1 station per 25,000 km2 for complex terrain is recommended.

0–249111 station/50,000 km2 as an average density over all zones in Scotland(2)
250–49912
500–99922
1,000–1,49933
1,500–1,99934
2,000–2,74945
2,750–3,74956
3,750 or more1 additional station per 2 million inhabitants1 additional station per 2 million inhabitants

PART 5Ozone: minimum number of sampling points for fixed measurements for zones attaining the long-term objectives

8.  In cases where zones attain the long-term objectives, the number of sampling points for ozone shall, in combination with other means of supplementary assessment such as air quality modelling and co-located nitrogen dioxide measurements, be sufficient to examine the trend of ozone pollution and check compliance with the long-term objectives.

9.  The number of stations located in agglomerations and other zones may be reduced to one third of the number specified in the Table in Part 4 of this schedule. Where information from fixed measurement stations is the sole source of information, at least one monitoring station shall be kept. If, in zones where there is supplementary assessment, the result of this is that a zone has no remaining station, co-ordination with the number of stations in neighbouring zones must ensure adequate assessment of ozone concentrations against long-term objectives.

10.  The number of rural background stations should shall be 1 per 100,000 km2.

Regulation 15(3) and (8) Regulation 17(2)(b)(ii) Regulation 19(2)(b) Regulation 20(3)(b)

SCHEDULE 6Location of sampling points

PART 1Macroscale siting for Group A pollutants

Sampling points for the protection of human health

1.  Sampling points directed at the protection of human health shall be sited to provide data on:–

(a)areas within zones where the highest concentrations occur to which the population is likely to be directly or indirectly exposed for a period which is significant in relation to the averaging period of the relevant limit value; and

(b)concentrations in other areas within the zones which are representative of the exposure of the general population.

2.  Sampling points shall in general be sited to avoid measuring very small micro-environments in their immediate vicinity. Where possible, the Scottish Ministers shall locate sampling points so as to be representative of air quality in a surrounding area of no less than 200 m2 at traffic-orientated sites and of several square kilometres at urban-background sites.

3.  Sampling points shall also, where possible, be representative of similar locations not in their immediate vicinity.

4.  Account shall be taken of the need to locate sampling points on islands, where that is necessary for the protection of human health.

Protection of ecosystems and vegetation

5.  Sampling points targeted at the protection of ecosystems or vegetation shall be sited more than 20 km from agglomerations or more than 5 km from other built-up areas, industrial installations or motorways. Where possible, the Scottish Ministers shall locate sampling points so as to be representative of air quality in a surrounding area of at least 1000 km2. A sampling point may be sited at a lesser distance or to be representative of air quality in a less extended area, taking account of geographical conditions. Account shall be taken of the need to assess air quality on islands.

PART 2Macroscale siting for Group B pollutants and polycyclic aromatic hydrocarbons

6.  The sites of sampling points shall be selected in such a way as to provide data on–

(a)the areas within zones where the population is likely to be directly or indirectly exposed to the highest concentrations averaged over a calendar year;

(b)concentrations in other areas within zones which are representative of the exposure of the general population;

(c)deposition rates representing the indirect exposure of the population through the food chain.

7.  Sampling points shall in general be sited so as to avoid measuring very small micro-environments in their immediate vicinity. Where possible, the Scottish Ministers shall locate sampling points so as to be representative of air quality in surrounding areas of no less than 200 m2 at traffic-orientated sites, at least 250 m × 250 m at industrial sites, where feasible, and several square kilometres at urban-background sites.

8.  Where the objective is to assess background levels the sampling site shall not be influenced by agglomerations or industrial sites in its vicinity, i.e. sites closer than a few kilometres (as the Scottish Ministers may determine in light of the circumstances of each case).

9.  Where contributions from industrial sources are to be assessed, at least one sampling point shall be installed downwind of the source in the nearest residential area. Where the background concentration is not known, an additional sampling point shall be situated within the main wind direction. In particular in cases falling within regulation 9(1)(a), the sampling points shall be sited such that the application of the measures referred to at regulation 7(2)(b) can be monitored.

10.  Sampling points shall also, where possible, be representative of similar locations not in their immediate vicinity. Where appropriate they shall be co-located with sampling points for PM10.

PART 3Macroscale siting for ozone

11.  Sampling points for ozone shall be located in accordance with the considerations set out in the following table–

Type of stationObjective of measurementRepresentativeness(1)Macroscale siting criteria
(1)

Sampling points shall also, where possible, be representative of similar locations not in their immediate vicinity.

UrbanProtection of human health: to assess the exposure of the urban population to ozone, i.e. where the population density and ozone concentration are relatively high and representative of the exposure of the general populationA few km2Away from the influence of local emissions such as traffic, petrol stations etc.; vented locations where well mixed levels can be measured; locations such as residential and commercial areas of cities, parks (away from the trees), big streets or squares with very little or no traffic open areas characteristic of education, sports or recreation facilities
SuburbanProtection of human health and vegetation: to assess the exposure of the population and vegetation located in the outskirts of the agglomeration, where the highest ozone levels, to which the population and vegetation is likely to be directly or indirectly exposed, occurSome tens of km2At a certain distance from the area of maximum emissions, downwind following the main wind direction during conditions favourable to ozone formation; where population, sensitive crops or natural ecosystems located in the outer fringe of an agglomeration are exposed to high ozone levels; where appropriate, some sub urban stations also upwind of the area of maximum emissions, in order to determine the regional background levels of ozone
RuralProtection of human health and vegetation: to assess the exposure of population, crops and natural ecosystems to sub-regional scale ozone concentrationsSub-regional levels (a few km2)Stations can be located in small settlements and/or areas with natural ecosystems, forests or crops; representative for ozone away from the influence of immediate local emissions such as industrial installations and roads; at open area sites, but not on higher mountain-tops
Rural backgroundProtection of vegetation and human health: to assess the exposure of crops and natural ecosystems to regional-scale ozone concentrations as well as exposure of the populationsRegional/national/continental levels (1,000 to 10,000 km2)Station located in areas with lower population density, e.g. with natural ecosystems, forests, far removed from urban and industrial areas and away from local emissions; avoid locations which are subject to locally enhanced formation of near ground inversion conditions, also summits of higher mountains; coastal sites with pronounced diurnal wind cycles of local character are not recommended by Directive 2002/3/EC

12.  For rural and rural background stations, consideration shall be given, where appropriate, to co ordination with the monitoring requirements of Commission Regulation 1091/94(1) concerning protection of the Community’s forests against atmospheric pollution.

PART 4Microscale siting

13.  The following guidelines shall be met as far as practicable–

(a)the flow around the inlet sampling probe shall be unrestricted, (and, for ozone sampling, free in an arc of at least 270°) without any obstructions affecting the airflow in the vicinity of the sampler–

(i)in the case of Group A and Group B pollutants, the inlet sampling probe shall normally be some metres away from buildings, balconies, trees and other obstacles and at least 0.5 m from the nearest building in the case of sampling points representing air quality at the building line; and

(ii)in the case of ozone, the inlet sampling probe shall be away from buildings, balconies, trees and other obstacles by more than twice the height the obstacle protrudes above the sampler;

(b)in general, the inlet sampling point shall be between 1.5 m (the breathing zone) and 4 m above the ground. However, higher positions (up to 8 m) may be necessary in some circumstances and (for ozone sampling) in wooded areas. Higher siting may also be appropriate if the station is representative of a large area;

(c)the inlet probe shall not be positioned in the immediate vicinity of sources in order to avoid the direct intake of emissions unmixed with ambient air;

(d)the sampler’s exhaust outlet shall be positioned so that recirculation of exhaust air to the sampler inlet is avoided;

(e)in relation to the location of traffic orientated samplers for Group A and Group B pollutants:–

(i)sampling points shall be at least 25 m from the edge of major junctions and at least 4 m from the centre of the nearest traffic lane;

(ii)for nitrogen dioxide and carbon monoxide, inlets shall be no more than 5 m from the kerbside; and

(iii)for PM10, lead, benzene and Group B pollutants, inlets shall be sited so as to be representative of air quality near to the building line;

(f)for ozone, the inlet probe shall be positioned well away from such sources as furnaces and incineration flues and more than 10 m from the nearest road, with distance increasing as a function of traffic intensity; and

(g)for deposition measurements in rural background areas as respects Group B pollutants and other pollutants falling within regulations 19 and 20, the European Monitoring and Evaluation of Pollutants guidelines and criteria shall be applied as far as practicable and where not provided for elsewhere in these Regulations.

14.  The following factors may also be taken into account–

(a)interfering sources;

(b)security;

(c)access;

(d)availability of electrical power and telephone communications;

(e)visibility of the site in relation to its surroundings;

(f)safety of public and operators;

(g)the desirability of co-locating sampling points for different pollutants;

(h)planning requirements.

PART 5Documentation and review of site selection

15.  The site-selection procedures shall be fully documented at the classification stage by such means as compass-point photographs of the surrounding area and a detailed map. Sites shall be reviewed at regular intervals with repeated documentation to ensure that selection criteria remain valid over time.

16.  For ozone, this requires screening and interpretation of the monitoring data in the context of the meteorological and photochemical processes affecting the ozone concentrations measured at the respective site.

Regulation 15(6)(b) Regulation 16(1)

SCHEDULE 7Requirements for assessment methods other than fixed measurement

PART 1Group A pollutants

1.  The following information shall be compiled for zones within which sources other than fixed measurement are employed to supplement information from fixed measurement or as the sole means of air quality assessment–

(a)a description of assessment activities carried out;

(b)the specific methods used, with references to descriptions of the method;

(c)the sources of data and information;

(d)a description of results, including uncertainties and, in particular, the extent of any area or, if relevant, the length of road within the zone over which concentrations exceed the limit value or, as may be, the limit value plus applicable margin of tolerance and of any area within which concentrations exceed the upper assessment threshold or the lower assessment threshold; and

(e)for limit values the object of which is the protection of human health, the population potentially exposed to concentrations in excess of the limit value.

2.  Where possible maps shall be compiled showing concentration distributions within each zone.

PART 2Group B pollutants

Requirements for air quality models

3.  Where an air quality model is used for assessment, references to descriptions of the model and information on the uncertainty shall be compiled. The uncertainty for modelling is defined as the maximum deviation of the measured and calculated concentration levels, over a full year, without taking into account the timing of the events.

Requirements for objective estimation techniques

4.  Where objective estimation techniques are used, the uncertainty shall not exceed 100%.

Standardisation

5.  For substances to be analysed in the PM10 fraction, the sampling volume shall refer to ambient conditions.

PART 3Ozone and ozone precursor substances

6.  The following information shall be compiled for zones within which sources other than fixed measurement are employed to supplement information from measurement–

(a)a description of the assessment activities carried out;

(b)specific methods used, with references to descriptions of the method;

(c)sources of data and information;

(d)a description of results, including uncertainties and, in particular, the extent of any area within the zone over which concentrations exceed long-term objectives or target values; and

(e)for long-term objectives or target values whose object is the protection of human health, the population potentially exposed to concentrations in excess of the threshold.

7.  The Scottish Ministers shall ensure that maps are compiled showing concentration distributions within each zone.

Regulation 16(2) Regulation 17(2)(d) Regulation 19(4) Regulation 20(4)

SCHEDULE 8Data quality objectives

PART 1Group A pollutants and PM2·5

Group A pollutants (other than benzene and carbon monoxide) and PM2·5

1.  The data-quality objectives set out in the following table for the required uncertainty of assessment methods, of minimum time coverage and of data capture of measurement are laid down to guide quality assurance programmes–

Sulphur dioxide, nitrogen dioxide and oxides of nitrogenLead, PM2·5 and PM10
Continuous measurement
Uncertainty15%25%
Minimum data capture90%90%
Indicative measurement
Uncertainty25%50%
Minimum data capture90%90%
Minimum time coverage14% (One measurement a week at random, evenly distributed over the year, or eight weeks evenly distributed over the year)14% (One measurement a week at random, evenly distributed over the year, or eight weeks evenly distributed over the year)
Modelling
Uncertainty
Hourly averages50%–60%
Daily averages50%
Annual averages30%50%
Objective estimation
Uncertainty75%100%

2.  The uncertainty of the measurement is defined as that set out in the “Guide to the Expression of Uncertainty of Measurements” (ISO 1993)(2) or in ISO 5725-1 “Accuracy (trueness and precision) of measurement methods and results” (ISO 1994). The percentages in the table at paragraph 1 are given for individual measurements averaged, over the period considered, by the limit value, for a 95% confidence interval (bias + two times the standard deviation). The uncertainty for continuous measurements shall be interpreted as being applicable in the region of the appropriate limit value.

3.  The uncertainty for modelling and objective estimation is defined as the maximum deviation of the measured and calculated concentration levels, over the period considered by the limit value, without taking account the timing of the events.

4.  The requirements for minimum data capture and time coverage do not include losses of data due to the regular calibration or the normal maintenance of the instrumentation.

5.  The Scottish Ministers may allow for random measurements to be made instead of continuous measurements for lead, PM2·5 and PM10 by methods for which uncertainty within the 95% confidence interval with respect to continuous monitoring has been demonstrated to be within 10%. Random sampling shall be spread evenly over the year.

Benzene and carbon monoxide

6.  The data quality objectives set out in the following table, for allowed uncertainty of assessment methods, of minimum time coverage and of data capture of measurement are provided to guide quality assurance programmes–

BenzeneCarbon monoxide
Fixed measurements
Uncertainty25%15%
Minimum data capture90%90%
Minimum time coverage35% urban background and traffic sites (distributed over the year to be representative of various conditions for climate and traffic); 90% industrial sites
Indicative measurements
Uncertainty30%25%
Minimum data capture90%90%
Minimum time coverage14% (one day’s measurement a week at random, evenly distributed over the year, or eight weeks evenly distributed over the year)14% (one measurement a week at random, evenly distributed over the year, or eight weeks evenly distributed over the year)
Modelling
Uncertainty:
Eight-hour averages50%
Annual averages50%
Objective estimation
Uncertainty100%75%

7.  The uncertainty (on a 95% confidence interval) of the assessment methods shall be evaluated in accordance with the “Guide to the Expression of Uncertainty of Measurements” (ISO 1993) or the methodology of ISO 5725:1994. The percentages for uncertainty in the table in paragraph 6 are given for individual measurements averaged over the period considered by the limit value, for a 95% confidence interval. The uncertainty for the fixed measurements shall be interpreted as being applicable in the region of the appropriate limit value.

8.  The uncertainty for modelling and objective estimation is defined as the maximum deviation of the measured and calculated concentration levels, over the period considered by the limit value, without taking into account the timing of the events.

9.  The requirements for minimum data capture and time coverage do not include losses of data due to the regular calibration or the normal maintenance of the instrumentation.

10.  The Scottish Ministers may allow for random measurements to be made instead of continuous measurements for benzene if the uncertainty, including the uncertainty due to random sampling, meets the quality objective of 25%. Random sampling shall be spread evenly over the year.

PART 2Group B pollutants, polycyclic aromatic hydrocarbons and total gaseous mercury

11.  The data quality objectives set out in the following table are provided to guide quality assurance–

Benzo(a)pyreneArsenic, cadmium and nickelPolycyclic aromatic hydrocarbons and total gaseous mercuryTotal deposition
(1)

Indicative measurement being measurements which are performed at reduced regularity but fulfil the other data quality objectives.

Uncertainty
Fixed and indicative measurements50%40%50%70%
Modelling60%60%60%60%
Minimum data capture90%90%90%90%
Minimum time coverage
Fixed measurements33%50%
Indicative measurements(1)14%14%14%33%

12.  The uncertainty (expressed at a 95% confidence level) of the methods used for the assessment of ambient air concentrations shall be evaluated in accordance with the CEN Guide to the Expression of Uncertainty in Measurement (ENV 13005-1999)(3), the methodology of ISO 5725:1994, and the guidance provided in the CEN Report, “Air quality – Approach to uncertainty estimation for ambient air reference measurement methods” (CR 14377:2002E). The percentages for uncertainty in the table in paragraph 11 are given for individual measurements, which are averaged over typical sampling times, for a 95% confidence interval. The uncertainty of the measurements shall be interpreted as being applicable in the region of the appropriate target value. Fixed and indicative measurements shall be evenly distributed over the year in order to avoid skewing of results.

13.  The requirements for minimum data capture and time coverage do not include losses of data due to regular calibration or normal maintenance of the instrumentation. Twenty-four-hour sampling is required for the measurement of benzo(a)pyrene and polycyclic aromatic hydrocarbons. With care, individual samples taken over a period of up to one month may be combined and analysed as a composite sample, provided the method ensures that the samples are stable for that period. Where the three congeners benzo(b)fluoranthene, benzo(j)fluoranthene, benzo(k)fluoranthene, are difficult to resolve analytically, they may be reported as sum. The Scottish Ministers shall endeavour, in so far as practicable, to undertake twenty-four hour sampling for the measurement of arsenic, cadmium and nickel concentrations. Sampling shall be spread evenly over the weekdays and the year. For the measurement of deposition rates the Scottish Ministers shall endeavour, in so far as practicable, to obtain monthly, or weekly, samples throughout the year.

14.  The Scottish Ministers may allow for use of wet only instead of bulk sampling if it can be demonstrated to their satisfaction that the difference between them is within 10%. Deposition rates shall generally be given as μg/m3 per day.

15.  The Scottish Ministers may apply a minimum time coverage lower than indicated in the table at paragraph 11, but not lower than 14% for fixed measurements and 6% for indicative measurements provided that they are satisfied that it can be demonstrated that the 95% expanded uncertainty for the annual mean, calculated from the data quality objectives in the table at paragraph 11 according to ISO 11222:2002 – “Determination of the uncertainty of the time average of air quality measurements” will be met.

PART 3Ozone and related nitrogen oxide and nitrogen dioxide assessed at ozone sampling points

16.  The data quality objectives set out in the following table, for allowed uncertainty of assessment methods, of minimum time coverage and of data capture of measurement, are provided to guide quality-assurance programmes–

For ozone, NO and NO2 assessed at ozone sampling points
Continuous fixed measurement
Uncertainty of individual measurements15%
Minimum data capture90% during summer; 75% during winter
Indicative measurement
Uncertainty of individual measurements30%
Minimum data capture90%
Minimum time coverage>10% during summer
Modelling
Uncertainty
1 hour averages (daytime)50%
8 hours daily maximum50%
Objective estimation
Uncertainty75%

17.  The uncertainty (on a 95% confidence interval) of the measurement methods shall be evaluated in accordance with the principles laid down in the “Guide to the Expression of Uncertainty of Measurements” (ISO 1993) or the methodology in ISO 5725-1 “Accuracy (trueness and precision) of measurement methods and results” (ISO 1994) or equivalent. The percentages for uncertainty in the table at paragraph 16 are given for individual measurements, averaged over the period for calculating target values and long-term objectives, for a 95% confidence interval. The uncertainty for continuous fixed measurements shall be interpreted as being applicable in the region of the concentration used for the appropriate threshold.

18.  The uncertainty for modelling and objective estimation means the maximum deviation of the measured and calculated concentration levels, over the period for calculating the appropriate threshold, without taking into account the timing of events.

19.  “Time coverage” means the percentage of time considered for settling the threshold value during which the pollutant is measured.

20.  “Data capture” means the ratio of the time for which the instrument produces valid data, to the time for which the statistical parameter or aggregated value is to be calculated.

21.  The requirements for minimum data capture and time coverage do not include losses of data due to the regular calibration or normal maintenance of the instrument.

Regulation 16(3) Regulation 19(4) Regulation 20(4)

SCHEDULE 9Reference methods

PART 1Group A pollutants

Reference method
Sampling and measurement of benzeneEN 14662:2005, Parts 1, 2 and 3 “Ambient air quality – standard method for measurement of benzene concentrations”(4)
Analysis of carbon monoxideEN 14626:2005 “Ambient air quality – Standard method for the measurement of the concentration of carbon monoxide by nondispersive infrared spectroscopy”
Sampling of leadThe same reference method as for PM10
Analysis of leadISO 9855: 1993 Ambient air – Determination of the particulate lead content of aerosols collected in filters. Atomic absorption spectroscopy method
Analysis of nitrogen dioxide and oxides of nitrogenISO 7996: 1985 Ambient air – determination of the mass concentrations of nitrogen oxides – chemiluminescence method
Sampling and measurement of PM10EN 12341:1998 “Air Quality – Field Test Procedure to Demonstrate Reference Equivalence of Sampling Methods for the PM10 fraction of particulate matter”. The measurement principle is based on the collection on a filter of the PM10 fraction of ambient particulate matter and the gravimetric mass determination
Analysis of sulphur dioxideISO/FDIS 10498 (Standard in draft) Ambient air – determination of sulphur dioxide – ultraviolet fluorescence method

PART 2Group B pollutants in ambient air

Reference method
Sampling of Group B pollutants other than benzo(a)pyreneThe same method as for sampling and measurement of PM10
Analysis of Group B pollutants other than benzo(a)pyreneEN 14902:2005 “Ambient air quality – standard method for the measurement of Pb, Cd, As and NI in the PM10 fraction of suspended particulate matter”
Benzo(a)pyrene concentrationsA method based on manual PM10 sampling equivalent to EN 12341

PART 3Ozone

Reference method
Measurement of ozoneEN 14625:2005 “Ambient air quality – standard method for the measurement of the concentration of ozone by ultraviolet photometry”

PART 4Other reference methods

Reference method
Sampling and analysis of polycyclic aromatic hydrocarbons in ambient airA method based on manual PM10 sampling equivalent to EN 12341
Sampling and analysis of mercury in ambient airAn automated method based on Atomic Absorption Spectrometry or Atomic Fluorescence Spectrometry
Sampling and analysis of the deposition of Group B pollutants, mercury, and polycyclic aromatic hydrocarbonsA method based on the exposition of cylindrical deposit gauges with standardised dimensions

Regulation 18

SCHEDULE 10Ozone precursor substances

Objectives

1.  The main objectives of measurements of ozone precursor substances are to analyse any trend in ozone precursors, to check the efficiency of emission reduction strategies, to check the consistency of emission inventories and to help attribute emission sources to pollution concentration.

2.  An additional aim is to support the understanding of ozone formation and precursor dispersion processes, as well as the application of photochemical models.

Substances

3.  Measurements of ozone precursor substances shall include at least nitrogen oxides, and appropriate volatile organic compounds. For the purposes of this Schedule, “volatile organic compounds” means all organic compounds from anthropogenic and biogenic sources, other than methane, that are capable of producing photochemical oxidants by reaction with nitrogen oxides in the presence of sunlight.

4.  The Scottish Ministers shall, in particular, consider measuring the following volatile organic compounds–

Ethane1-ButeneIsopreneEthyl benzene
Ethylenetrans-2-Butenen-Hexanem+p-Xylene
Acetylenecis-2-Butenei-Hexaneo-Xylene
Propane1.3-Butadienen-Heptane1,2,4-Trimeth. benzene
Propenen-Pentanen-Octane1,2,3-Trimeth. benzene
n-Butanei-Pentanei-Octane1,3,5-Trimeth. benzene
i-Butane1-PenteneBenzeneFormaldehyde
2-PenteneTolueneTotal non-methane hydrocarbons

Reference methods

5.  The reference method for the analysis of oxides of nitrogen shall be ISO 7996:1985, Ambient air – determination of the mass concentrations of nitrogen oxides – chemiluminescence method.

Monitoring sites

6.  Measurements shall be taken in particular in urban and suburban areas at any monitoring site considered appropriate with regard to the objectives set out in this Schedule.

Regulation 24(1)

SCHEDULE 11Public information where alert or information thresholds are exceeded

PART 1Alert thresholds for nitrogen dioxide and sulphur dioxide

1.  In cases where the alert thresholds for nitrogen dioxide or sulphur dioxide are exceeded, the information to be made available to the public shall include at least–

(a)the date, hour and place of the occurrence and the reasons for the occurrence, where known;

(b)any forecasts of–

(i)changes in concentration (improvement, stabilisation, or deterioration), together with the reasons for those changes;

(ii)the geographical area concerned; and

(iii)the duration of the occurrence;

(c)the type of population potentially sensitive to the occurrence; and

(d)the precautions to be taken by the sensitive population concerned.

PART 2Alert and information thresholds for ozone

2.  In cases where either the information threshold or the alert threshold for ozone–

(a)is exceeded; or

(b)is predicted to be exceeded,

the details set out in paragraphs 3 to 6 shall, as a minimum, be made available to the public on a sufficiently large scale.

3.  Information on any observed exceedance–

(a)the location or area of the exceedance;

(b)the type of threshold exceeded (information threshold or alert threshold);

(c)the time at which the exceedance began and its duration; and

(d)the highest 1-hour and 8-hour mean concentration.

4.  Forecast for the following afternoon, day or days–

(a)the geographical area of expected exceedances of an information threshold or alert threshold; and

(b)the expected change in pollution, that is, improvement, stabilisation or deterioration.

5.  Information on the type of population concerned, possible health effects and recommended conduct, in particular–

(a)information on population groups at risk;

(b)description of likely symptoms;

(c)recommended precautions to be taken by the population concerned; and

(d)where to find further information.

6.  Information provided under this Schedule shall also include–

(a)information on preventive action to reduce pollution and/or exposure to it;

(b)an indication of main source sectors; and

(c)recommendations for action to reduce emissions.

Regulations 26(2)(a) & 29

SCHEDULE 12Collation of information and criteria for aggregating data and calculating statistical parameters

PART 1Information to be submitted to the Commission

1.  The following information on ozone concentrations shall be obtained and collated–

Type of stationLevelAveraging/accumulation timeProvisional data for each month from April to SeptemberReport for each year
(1)

Maximum daily 8-hour mean.

(2)

In this table, “AOT40” has the same meaning as in paragraph 3(d) of Part 4 of Schedule 1.

Information thresholdAny180μg/m31 hourFor each day with any exceedance: date, total hours of, exceedance, maximum 1 hour ozone and related NO2 values when required and monthly 1 hour maximum ozoneFor each day with any exceedance: date, total hours of exceedance, maximum 1 hour ozone and related NO2 values, when required
Alert thresholdAny240μg/m31 hourFor each day with any exceedance: date, total hours of exceedance, maximum 1 hour ozone and related NO2 values, when requiredFor each day with any exceedance: date, total hours of exceedance, maximum 1 hour ozone and related NO2 values, when required
Health protectionAny120μg/m38 hoursFor each day with any exceedance: date, 8 hours maximum(1)For each day with any exceedance: date, 8 hours maximum(1)
Vegetation protectionSuburban, rural, rural backgroundAOT40(2) = 6,000 μg/m3.h1 hour, accumulated from May to JuneValue
Forest protectionSuburban, rural, rural backgroundAOT40(2) = 20,000μg/m3.h1 hour, accumulated from April to SeptemberValue
MaterialsAny40 μg/m31 yearValue

2.  The Scottish Ministers shall also ensure that the following information is collated–

(a)for ozone, nitrogen dioxide, oxides of nitrogen and the sums of ozone and nitrogen dioxide (added as parts per billion and expressed in μg/m3 ozone) the maximum, 99.9th, 98th and 50th percentiles and annual average and number of valid data from hourly series; and

(b)the maximum, 98th and 50th percentile and annual average from a series of daily 8-hour ozone maxima.

3.  Data collated in monthly reports shall be considered provisional and shall be updated where necessary in subsequent submissions.

PART 2Criteria for aggregating data and calculating statistical parameters

4.  In this Part, percentiles are to be calculated using the method specified in Council Decision 97/101/EC(5) establishing a reciprocal exchange of information and data from networks and individual stations measuring ambient air pollution within member States.

5.  The following criteria are to be used for checking validity when aggregating data and calculating statistical parameters–

ParameterRequired proportion of valid data
(1)

In this table “AOT40” has the same meaning as in paragraph 3(d) of Part 4 of Schedule 1.

(2)

In cases where all possible measured data are not available, the following factor shall be used to calculate AOT40 values: AOT40 (estimate) = AOT40 measured x (total possible number of hours ÷ number of measured hourly values). The reference in this formula to the total possible number of hours is to the hours within the time period of AOT40 definition (that is, 08:00 to 20:00 Central European Time from 1st May to 31st July each year, for vegetation protection and from 1st April to 30th September each year for forest protection).

1 hour values75% (45 minutes)
8 hour values75% of values (6 hours)
Maximum daily 8 hours mean from hourly running 8 hours averages75% of the hourly running 8 hour averages (18 8 hours averages per day)
AOT40(1)90% of the 1 hour values over the time period defined for calculating the AOT40 value(2)
Annual mean75% of the 1 hour values over summer (April to September) and winter (January to March, October to December) seasons separately
Number of exceedances and maximum values per month

90% of the daily maximum 8 hours mean value (27 available daily values per month)

90% of the 1 hour values between 08:00 and 20:00 Central European Time

Number of exceedances and maximum values per yearFive out of six summer months over the summer season (April to September)
(1)

O.J. No L 125, 18.05.94, p.1.

(2)

Copies of International Standards Organisation publications referred to in this Schedule or in Schedule 9 may be purchased from the British Standards Institution (“BSI”) Sales Department either by telephone (0208 996 9001) or by post from the BSI, Standards House, 389 Chiswick High Road, London W4 4AL, http://www.bsi-global.com.

(3)

European Committee for Standardisation (CEN) publication; (copies may be obtained from CEN at 36, Rue de Stassart, B 1050, Brussels, Belgium, http://www.cenorm.be).

(4)

This standard is issued by the European Committee for Standardisation (CEN); (copies may be obtained from CEN at 36, Rue Stassart B-1050, Brussels, Belgium, http://www.cenorm.be).

(5)

O.J. L 35, 05.02.97, p.14.

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