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The Air Quality Limit Values (Scotland) Regulations 2001

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Regulations 2, 3, 8(2), 9(1), 11(5)

SCHEDULE 1LIMIT VALUES, MARGINS OF TOLERANCE ETC.

PART ISULPHUR DIOXIDE

Limit values for sulphur dioxide

Averaging PeriodLimit valueMargin of Tolerance(1)Date by which limit value is to be met

1.  Hourly limit value for the protection of human health

1 hour350 μg/m3, not to be exceeded more than 24 times a calendar year470 μg/m3 on 19th July 2001 reducing on 1st January of each following year by 30 μg/m3 to reach 350 μg/m3 by 1st January 20051st January 2005

2.  Daily limit value for the protection of human health

24 hours125 μg/m3, not to be exceeded more than 3 times a calendar yearNone1st January 2005

3.  Limit value for the protection of ecosystems

Calendar year and winter (1st October to 31st March)20 μg/m3None19th July 2001

Alert threshold for sulphur dioxide

1.2  500 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.

Minimum Details to be made available to the public when the alert threshold for sulphur dioxide is exceeded

1.3  Details to be made available to the public should include at least:

  • the date, hour and place of the occurrence and the reasons for the occurrence, where known;

  • any forecasts of:

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

    • the geographical area concerned,

    • the duration of the occurrence,

    • the type of population potentially sensitive to the occurrence,

    • the precautions to be taken by the sensitive population concerned.

PART IINITROGEN DIOXIDE (NO2) AND OXIDES OF NITROGEN (NOx)

Limit values for nitrogen dioxide and oxides of nitrogen

Averaging PeriodLimit valueMargin of toleranceDate by which limit value is to be met

1.  Hourly limit value for the protection of human health

1 hour200μg/m3 NO2 not to be exceeded more than 18 times a calendar year290μg/m3 on 19th July 2001, reducing on 1st January of each following year by 10μg/m3 to reach 200μg/m3 by 1st January 20101st January 2010

2.  Annual limit value for the protection of human health

Calendar year40μg/m3 NO258μg/m3 on 19th July 2001 reducing on 1st January of each following year by 2μg/m3 to reach 40μg/m3 by 1st January 20101st January 2010

3.  Annual limit value for the protection of vegetation

Calendar year30 μg/m3 NOxNone19th July 2001

Alert threshold for nitrogen dioxide

2.2  400 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.

Minimum Details to be made available to the public when the alert threshold for nitrogen dioxide is exceeded

2.3  Details to be made available to the public should include at least:

  • the date, hour and place of the occurrence and the reasons for the occurrence, where known;

  • any forecasts of:

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

    • the geographical area concerned,

    • the duration of the occurrence,

  • the type of population potentially sensitive to the occurrence,

  • the precautions to be taken by the sensitive population concerned.

PART IIIPARTICULATE MATTER (PM10)

Averaging PeriodLimit valueMargin of toleranceDate by which limit value is to be met

1.  24-hour limit value for the protection of human health

24 hours50μg/m3 PM10 not to be exceeded more than 35 times a calendar year70μg/m3 on 19th July 2001, reducing on 1st January of each following year by 5μg/m3 to reach 50μg/m3 by 1st January 20051st January 2005

2.  Annual limit value for the protection of human health

Calendar year40 μg/m3 PM1046.4μg/m3 on 19th July 2001, reducing on 1st January of each following year by 1.6μg/m3 to reach 40μg/m3 by 1st January 20051st January 2005

PART IVLEAD

Averaging PeriodLimit valueMargin of toleranceDate by which limit value is to be met
Annual limit value for the protection of human healthCalendar year0.5 μg/m30.9μg/m3 on 19th July 2001, reducing on 1st January of each following year by 0.1μg/m3 to reach 0.5μg/m3 by 1st January 20051st January 2005

Regulations 5(5) and 6

SCHEDULE 2UPPER AND LOWER ASSESSMENT THRESHOLDS AND EXCEEDANCES

PART IUPPER AND LOWER ASSESSMENT THRESHOLDS

The following upper and lower assessment thresholds will apply:

(a)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 year)60% 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 year)40% of winter limit value (8 μg/m3)

(b)NITROGEN DIOXIDE AND OXIDES OF NITROGEN

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 year)80% 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 year)65% of limit value (26 μg/m3)65% of limit value (19.5 μg/m3)

(c)PARTICULATE MATTER(2)

24-hour averageAnnual average
Upper assessment threshold60% of limit (30 μg/m3, not to be exceeded more than seven times in any calendar year)70% of limit value (14 μg/m3)
Lower assessment threshold40% of limit value (20 μg/m3, not to be exceeded more than seven times in any calendar year)50% of limit value (10 μg/m3)

(d)LEAD

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

PART IIDETERMINATION OF EXCEEDANCES OF UPPER AND LOWER ASSESSMENT THRESHOLDS

Exceedances of upper and lower assessment thresholds must be determined on the basis of concentrations during the previous five years where sufficient data are available. An assessment threshold will be deemed to have been exceeded if during those five years the total number of exceedances of the numerical concentration of the threshold is more than three times the number of exceedances allowed each year.

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 pollution levels may be combined with results obtained from information from emission inventories and modelling to determine exceedances of the upper and lower assessment thresholds.

Regulation 7(3)

SCHEDULE 3LOCATION OF SAMPLING POINTS FOR THE MEASUREMENT OF SULPHURDIOXIDE, NITROGEN DIOXIDE AND OXIDES OF NITROGEN, PARTICULATE MATTER AND LEAD IN AMBIENT AIR.

The following considerations will apply to fixed measurement.

PART IMACROSCALE SITING

Protection of human health

(a)Sampling points directed at the protection of human health should be sited:

(i)to provide data on the areas within zones and agglomerations 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 limit value(s);

(ii)to provide data on levels in other areas within the zones and agglomerations which are representative of the exposure of the general population.

Sampling points should in general be sited to avoid measuring very small micro-environments in their immediate vicinity. As a guideline, a sampling point should be sited 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.

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

Account should 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

(b)Sampling points targeted at the protection of ecosystems or vegetation should be sited more than 20 km from agglomerations or more than 5 km from other built-up areas, industrial installations or motorways. As a guideline, a sampling point should be sited to be representative of air quality in a surrounding area of at least 1 000 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 should be taken of the need to assess air quality on islands.

PART IIMICROSCALE SITING

The following guidelines should be met as far as practicable:

  • the flow around the inlet sampling probe should be unrestricted without any obstructions affecting the airflow in the vicinity of the sampler (normally 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);

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

  • the inlet probe should not be positioned in the immediate vicinity of sources in order to avoid the direct intake of emissions unmixed with ambient air;

  • the sampler’s exhaust outlet should be positioned so that recirculation of exhaust air to the sampler inlet is avoided;

  • location of traffic-oriented samplers:

    • for all pollutants, such sampling points should be at least 25 m from the edge of major junctions and at least 4 m from the centre of the nearest traffic lane,

    • for nitrogen dioxide, inlets should be no more than 5 m from the kerbside,

    • for particulate matter and lead, inlets should be sited so as to be representative of air quality near to the building line.

The following factors may also be taken into account:

  • interfering sources;

  • security;

  • access;

  • availability of electrical power and telephone communications;

  • visibility of the site in relation to its surroundings;

  • safety of public and operators;

  • the desirability of co-locating sampling points for different pollutants;

  • planning requirements.

PART IIIDOCUMENTATION AND REVIEW OF SITE SELECTION

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

Regulation 7(4)

SCHEDULE 4CRITERIA FOR DETERMINING MINIMUM NUMBERS OF SAMPLING POINTS FOR FIXED MEASUREMENT OF CONCENTRATIONS OF RELEVANT POLLUTANTS IN AMBIENT AIR

PART IMINIMUM NUMBER OF SAMPLING POINTS FOR FIXED MEASUREMENT TO ASSESS COMPLIANCE WITH LIMIT VALUES FOR THE PROTECTION OF HUMAN HEALTH AND ALERT THRESHOLDS IN ZONES AND AGGLOMERATIONS WHERE FIXED MEASUREMENT IS THE SOLE SOURCE OF INFORMATION

Diffuse sources

Population of agglomeration or zone (thousands)If concentrations exceed the upper assessment thresholdIf maximum concentrations are between the upper and lower assessment thresholdsFor SO2 and NO2 in agglomerations where maximum concentrations are below the lower assessment threshold
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 0001053
For NO2 and particulate matter: to include at least one urban-background station and one traffic-orientated station

Point sources

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

PART IIMINIMUM 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
In island zones the number of sampling points for fixed measurement should be calculated taking into account the likely distribution patterns of ambient air pollution and the potential exposure of ecosystems or vegetation.
1 station every 20 000 km21 station every 40 000 km2

Regulation 7(5), (8)

SCHEDULE 5DATA-QUALITY OBJECTIVES AND COMPILATION OF RESULTS OF AIR QUALITY ASSESSMENT

PART IDATA-QUALITY OBJECTIVES

The following data-quality objectives for the required accuracy 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 nitrogenParticulate matter and lead
Continuous measurement
Accuracy15%25%
Minimum data capture90%90%
Indicative measurement
Accuracy25%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
Accuracy:
Hourly averages50%–60%
Daily averages50%
Annual averages30%50%
Objective estimation
Accuracy:75%100%

The accuracy of the measurement is defined as laid down in the “Guide to the Expression of Uncertainty of Measurements” (ISO 1993)(3) or in ISO 5725-1 “Accuracy (trueness and precision) of measurement methods and results” (ISO 1994)(4). The percentages in the table 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 accuracy for continuous measurements should be interpreted as being applicable in the region of the appropriate limit value.

The accuracy 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.

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.

The Scottish Ministers may allow for random measurements to be made instead of continuous measurements for particulate matter and lead by methods for which accuracy within the 95% confidence interval with respect to continuous monitoring has been demonstrated to be within 10%. Random sampling must be spread evenly over the year.

PART IIRESULTS OF AIR QUALITY ASSESSMENT

The following information should be compiled for zones or agglomerations within which sources other than measurement are employed to supplement information from measurement or as the sole means of air quality assessment:

  • a description of assessment activities carried out;

  • the specific methods used, with references to descriptions of the method;

  • the sources of data and information;

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

  • 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.

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

Regulation 7(6)

SCHEDULE 6REFERENCE METHODS FOR ASSESSMENT OF CONCENTRATIONS OF SULPHUR DIOXIDE, NITROGEN DIOXIDE AND OXIDES OF NITROGEN, PARTICULATE MATTER (PM10 AND PM2.5) AND LEAD

PART IREFERENCE METHOD FOR THE ANALYSIS OF SULPHUR DIOXIDE:

ISO/FDIS 10498 (Standard in draft) Ambient air – determination of sulphur dioxide – ultraviolet fluorescence method(5).

PART IIREFERENCE METHOD FOR THE ANALYSIS OF NITROGEN DIOXIDE AND OXIDES OF NITROGEN:

ISO 7996: 1985 Ambient air – determination of the mass concentrations of nitrogen oxides – chemiluminescence method(6).

PART IIIAREFERENCE METHOD FOR THE SAMPLING OF LEAD:

The reference method for the sampling of lead will be that described in the Annex to Directive 82/884/EEC(7) until such time as the limit value in Schedule 1 to these Regulations is to be met, when the reference method will be that for PM10 as laid down in Part IV of this Schedule.

PART IIIBREFERENCE METHOD FOR THE ANALYSIS OF LEAD:

ISO 9855: 1993 Ambient air – Determination of the particulate lead content of aerosols collected in filters. Atomic absorption spectroscopy method(8).

PART IVREFERENCE METHOD FOR THE SAMPLING AND MEASUREMENT OF PM10

The reference method for the sampling and measurement of PM10 will be that described in EN 12341 “Air Quality – Field Test Procedure to Demonstrate Reference Equivalence of Sampling Methods for the PM10 fraction of particulate matter”(9). The measurement principle is based on the collection on a filter of the PM10 fraction of ambient particulate matter and the gravimetric mass determination.

Regulation 9(1), (3), (4)

SCHEDULE 7INFORMATION TO BE INCLUDED IN THE PLAN OR PROGRAMME FOR IMPROVEMENT OF AMBIENT AIR QUALITY

Localization of excess pollution

  • 1.  region

  • city (map)

  • measuring station (map, geographical coordinates).

General information

  • 2.  type of zone (city, industrial or rural area)

  • estimate of the polluted area (km2) and of the populations exposed to the pollution

  • useful climatic data

  • relevant data on topography

  • sufficient information on the type of targets requiring protection in the zone.

Responsible authorities

3.  Names and addresses of persons responsible for the development and implementation of improvement plans.

Nature and assessment of pollution

  • 4.  concentrations observed over previous years (before the implementation of the improvement measures)

  • concentrations measured since the beginning of the project

  • techniques used for the assessment.

Origin of pollution

  • 5.  list of the main emission sources responsible for pollution (map)

  • total quantity of emissions from these sources (tonnes/year)

  • information on pollution imported from other regions.

Analysis of the situation

  • 6.  details of those factors responsible for the excess (transport, including cross-border transport, formation)

  • details of possible measures for improvement of air quality.

Details of those measures or projects for improvement which existed prior to 21st November 1996 i.e.

  • 7.  local, regional, national, international measures

  • observed effects of these measures.

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

  • 8.  listing and description of all the measures set out in the project

  • timetable for implementation

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

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

List of the publications, documents, work etc. used to supplement information requested in this Schedule.

(1)

The figures for Margins of Tolerance for each of the relevant pollutants given in this Schedule are calculated from those given in Annex I of Directive 99/30/EC (O.J. No. L 163, 22.4.99, p.41). This gave a figure above the limit value for each relevant pollutant, reducing by equal percentages from the date of entry into force of that Directive in 1999.

(2)

The upper and lower assessment thresholds for PM10 are based on the following indicative limit values for 1st January 2010, which will be reviewed in the light of further information on health and environmental effects, technical feasibility and experience in the application of the existing “Stage 1” limit values:

Averaging periodLimit valueMargin of toleranceDate by which limit value is to be met

1.  24-hour limit value for the production of human health

24 hours50 μg/m3 PM10 not to be exceeded more than 7 times a calendar yearTo be derived from date and to be equivalent to Stage 1 limit value1st January 2010

2.  Annual limit value for the protection of human health

Calendar year20 μg/m3 PM1050% on 1st January 2005 reducing every 12 months thereafter by equal percentages to reach 0% by 1st January 20101st January 2010
(3)

Copies of these International Standards Organisation publications can be purchased from the British Standards Institution “BSI” sales department either by telephone on 020-8996-9001 or by post from the BSI, Standards House, 389 Chiswick High Road, London W4 4AL.

(4)

Copies of these International Standards Organisation publications can be purchased from the British Standards Institution “BSI” sales department either by telephone on 020-8996-9001 or by post from the BSI, Standards House, 389 Chiswick High Road, London W4 4AL.

(5)

Copies of these International Standards Organisation publications can be purchased from the British Standards Institution “BSI” sales department either by telephone on 020-8996-9001 or by post from the BSI, Standards House, 389 Chiswick High Road, London W4 4AL.

(6)

Copies of these International Standards Organisation publications can be purchased from the British Standards Institution “BSI” sales department either by telephone on 020-8996-9001 or by post from the BSI, Standards House, 389 Chiswick High Road, London W4 4AL.

(7)

O.J. No. L 378, 31.12.82, p.15.

(8)

Copies of these International Standards Organisation publications can be purchased from the British Standards Institution “BSI” sales department either by telephone on 020-8996-9001 or by post from the BSI, Standards House, 389 Chiswick High Road, London W4 4AL.

(9)

European Standards Institute “CEN” publication reference BSEN 12341, obtainable from the British Standards Institute “BSI” as for footnote (a) above

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