Meteorological Data

4.1 Data for tables 4.1 to 4.8, maps 4.1 - 4.4 were supplied by the Met Office (Edinburgh) and the Met Office (Bracknell). The height above mean sea level for each climatological station is as follows:

	Height above
	mean sea
	level(m)
Aberdeen (Craibstone)		102
Dundee (Mayfield)		45
Edinburgh (Blackford Hill)		134
Royal Botanical Gardens (from 1992)		26
Glasgow (Abbotsinch)		5
Auchincruive (Strathclyde)		48
Bowhill (Selkirk)		168
Braemar		339
Dumfries		49
Inverness		4
Lerwick		82
Stornoway		15
Wick (automatic)		36

There was a change of site at Glasgow Airport from Renfrew to Abbotsinch in May 1966 and 1951/80 averages have been calculated using the combined data. From 1992 the site in Edinburgh has been the Royal Botanic Gardens.

4.2 The temperature maps 4.1 and 4.2 are based on observations from a large number of weather stations in Scotland averaged over the 30 year period 1961 to 1990. For some stations, data for shorter periods, or incomplete records have been weighted to give estimated values for the full 30 year period. The mean-daily temperature is obtained from the arithmetic mean of the mean daily maximum and mean daily minimum.

Air Quality Standards and Guidelines

4.3 Of the UK automatic urban and rural monitoring network sites, two have commenced operation recently - Glasgow Centre (July 1996) and Glasgow Kerbside (March 1997). Data for 1996 at the Glasgow Centre site are included in tables 4.10 - 4.14). In the UK, air quality for sulphur dioxide, smoke, nitrogen dioxide, ozone and lead is regulated by EC Directives. In addition, the World Health Organisation has issued air quality guidelines for a number of pollutants. In 1991, the Government established the Expert Panel on Air Quality Standards (EPAQS) to provide recommended air quality standards for the UK (the UK National Air Quality Strategy published in March 1997). A summary of these air quality standards, guidelines and objectives are given in tables 4.19 and 4.21. All objectives from the UK National Air Quality Strategy are to be achieved by the year 2005.

In addition, in order to describe air quality on a daily basis, the Government has revised the system of descriptors of air quality. The new system, introduced in November 1997 measures air pollution rather than air quality and aligns the thresholds with standards recommended by EPAQS. There are now specified air pollution bands of LOW, MODERATE, HIGH and VERY HIGH, for nitrogen dioxide, sulphur dioxide, ozone, carbon monoxide and fine particles. Information on air quality, on an hourly basis, is now provided on the air quality information line (0800 556677), on CEEFAX (page 410-417), TELETEXT (page106) and on the Internet
(http://www.environment.detr.gov.uk/airq/aqinfo.htm)

Lead and Other Elements

4.4 Lead is a trace element which is emitted into the environment by the consumption of leaded petrol, by the burning of coal and from metal works. Concentrations can accumulate in the environment and in the body, and can affect health, particularly in children. A range of trace elements, including lead, is monitored at two sites in Scotland - Motherwell and Glasgow. Data for lead, iron, and zinc are given in table 4.9. Concentrations of lead are generally decreasing, as a result of the increased use of unleaded petrol, and concentrations at both sites are well below the EC Directive limit value (2µgm^-3) and the WHO guideline concentration (0.5-1µgm^-3).

Tropospheric Ozone

4.5 Tropospheric ozone should not be confused with the stratospheric ozone layer, which protects the earth against harmful ultra-violet radiation. The troposphere is the lowest layer of the atmosphere, and although some ozone occurs here naturally, concentrations can be increased by reactions between pollutants which arise from human activity, mainly vehicle emissions. In addition to the effects on health, ozone can also reduce crop yield, cause damage to natural vegetation, contribute to acid rain formation, and damage some man made materials such as paints, elastomers and fabrics.

Rural ozone concentrations are monitored at 3 sites in Scotland as part of the national network of ozone monitoring stations in rural areas in the UK. The main objectives of this network are to provide a broad picture of the spatial and temporal variation of ozone concentrations, and to aid the assessment of the impact of this pollutant on sensitive areas. The results from the stations in Scotland are summarised in table 4.10. Urban monitoring of ozone commenced in Edinburgh in October 1992, and in Glasgow in 1996 as part of the UK Automatic Urban Monitoring Network. Ozone measurements at these sites are also presented in table 4.10. Under a continuing programme of quality control checking of data and international intercomparisons of primary standards, some retrospective re-scaling of UK rural ozone data has been necessary. Rural ozone measurements carried out from April 1991 to March 1993 have been re-scaled upwards by approximately 5%. Data presented in this table are derived from the corrected dataset.

Nitrogen Dioxide

4.6 Nitric oxide and nitrogen dioxide are gases formed in combustion processes, both from the nitrogen present in fuel and by the oxidation of nitrogen in air. High concentrations of nitrogen dioxide can affect the respiratory system, reduce plant growth, contribute to acid deposition, and play a part in the formation of tropospheric ozone. Hourly average concentrations of nitrogen oxides are currently monitored at Glasgow (3 sites) and Edinburgh(1 site) as part of the Automatic Urban Monitoring Network. A summary of data from these sites is given in table 4.11. Monitoring of hourly concentrations of oxides of nitrogen at the rural site, Strath Vaich, ceased in March 1997, although monitoring of NO2 with diffusion tubes continues at this site.

An extensive survey of NO² concentration measurements, with diffusion tube samplers, has been established in the UK in a collaborative programme between the central government and local authorities. The main aims of the survey are to identify areas of the UK which may require additional monitoring to ensure compliance with the EC Directive on NO² concentrations and to determine trends in NO² concentrations throughout the UK from a long running survey with a consistent siting and operational methodology. Results for 1995 at sites in Scotland located at the kerbsides of busy roads are shown in map 4.11 and corresponding results for sites in intermediate and urban background areas are shown in map 4.12. At intermediate and urban background sites in Scotland the maximum annual average concentration during 1995 was 25ppb, recorded in Glasgow. The overall average concentration for urban areas in Scotland was 13ppb. At kerbside locations, the overall average for Scotland was 23ppb and the maximum average concentration of 39ppb was also recorded in Glasgow.

Sulphur Dioxide

4.7 Sulphur dioxide is released by the combustion of sulphur containing fuels such as coal, smokeless fuel, and oil. Sulphur dioxide, particularly in combination with smoke, can cause temporary breathing problems for some people. This pollutant is also one of the principal contributors to acid rain. Hourly average concentrations are currently measured at 2 sites in Scotland : Glasgow and Edinburgh. Monitoring of hourly average SO₂ concentrations at the rural Strath Vaich site ceased in March 1997, though monitoring of SO₂ on a daily basis continues at this site as part of the UK Rural SO₂ Monitoring Network. A summary of the data from these sites is given in table 4.12. In addition, daily smoke and sulphur dioxide measurements are made at 40 sites in Scotland, to determine compliance with the EC Directive for these pollutants. Map 4.5 shows the annual average SO₂ concentration in air, in ppb, averaged over 20-20km grid squares containing one or more monitoring sites, for the period April 1995 to March 1996. Map 4.8 shows the corresponding data for smoke.

With improvements in emission inventory methodology and air monitoring techniques over the last few years, maps showing estimated pollutant concentrations at very fine resolution can now be produced. For example, map 4.5 shows, at a 1x1 km scale, estimated SO₂ concentrations in Scotland. The highest concentrations are found in urban areas - particularly around the Firth of Forth.

Carbon Monoxide

4.8 Carbon monoxide is primarily formed as a result of incomplete combustion of petrol in motor vehicles. It is toxic at high concentrations and affects physical co-ordination, vision and judgement. Hourly average carbon monoxide concentrations are measured in both Glasgow and Edinburgh, and the results are summarised in table 4.13.

Fine Particles

4.9 Particles in the size range which can penetrate the human thorax are generally called the thoracic fraction (generally referred to as PM10 because the size fraction is defined in relation to particles of aerodynamic diameter 10 mm). Recent studies have identified this particle size as significant in relation to effects on human health. Automatic hourly measurements of the thoracic particle size fraction are undertaken in both Edinburgh and Glasgow, and the data are presented in table 4.14.

Smoke Control Orders and Clean Air Grants

4.10 Under the Clean Air Act 1993, local authorities are empowered to make smoke control orders prohibiting the emission of smoke from buildings, including dwellings, in any part of their district. They can also give grants to householders to help them pay for new boilers and fires in newly-declared smoke control areas. Details of orders and grants made in 1995/96 are shown in table 4.15. Central Government funding for these grants ended on 31 March 1996.

Contraventions of Air Pollution Acts and Noise Complaints

4.11 Tables 4.16 - 4.18 are derived from the Annual Report on Environmental Health in Scotland for 1996-1997, published by the Royal Environmental Health Institute of Scotland. The information summarises the situation in 27 of the 32 councils, comprising 84 per cent of the population of Scotland.

Precipitation Composition Monitoring Network

4.12 The Government funds a national precipitation composition monitoring programme, co-ordinated by the National Environmental Technology Centre. The mean concentrations of the major ions in precipitation observed in 1995 are listed in table 4.20.

Wet Deposited Acidity

4.13 The annual mean non-marine sulphate concentration in 1995 is shown in map 4.7. The mean concentrations are larger in southern and eastern Scotland than in north western Scotland because precipitation in the north-west is mainly associated with airflow from the Atlantic and does not contain high levels of pollutants from the UK or Europe. The distribution of wet deposition, however, is determined largely by the variation in total rainfall and is largest in the south-west Highlands.

4.14 Additional information on acid deposition can be found in the report of the Review Group on Acid Rain, Acid Deposition in the United Kingdom, 1992-94 available from the Department of the Environment, Transport and The Regions, Publication Sales Department. Results from the monitoring network are published annually by the National Environmental Technology Centre, Culham, Oxfordshire (e.g Acid Deposition Monitoring in the UK: The First Ten Years, Report AEA - 1825/20017001/Issue 1.

Critical Load for Soils