Key Scottish Environment Statistics 2015

Air Quality

Background

Air quality can be affected by the emission of pollutants into the atmosphere from a wide range of sources, and has implications for both human health^[42] and the natural environment. The Air Quality Strategy^[43] (AQS) has introduced objectives that aim to improve air quality by reducing concentrations of several different pollutants.

Air Quality Management Areas

Local authorities with Air Quality Management Areas as at 31 July 2015^[44]

While the Air Quality Strategy focusses on improving air quality at a national level, localised areas of poor air quality may remain. To address this, the Local Air Quality Management (LAQM) system was established.

Under the LAQM system, all local authorities are required to regularly review air quality in their areas against several objectives for pollutants of particular concern for human health. If this work shows that any objective is not being achieved, the authority concerned must declare an Air Quality Management Area (AQMA) and produce an action plan outlining how it intends to tackle the issues identified.

As at 31 July 2015, there are 32 AQMAs in Scotland. Eight of these have been declared solely for PM₁₀ and a further 12 for both PM₁₀ and nitrogen dioxide (NO₂). Eleven of the remaining AQMAs are for NO₂ only and one is for sulphur dioxide (SO₂). All except the SO₂ AQMA have been declared on the basis of emissions from transport sources.

Targets and Indicators

Pollutant		AQS Objective	Year to be met
Nitrogen Dioxide (NO2)		1 hour mean of 200 µg/m3, not to be exceeded more than 18 times a year	2005
		Annual mean of 40 µg/m3
Ground level ozone		8-hour running mean of 100 µg/m3, not to be exceeded more than 10 days a year	2005
Particulate matter (PM10)	Stage 2	24 hour mean of 50 µg/m3, not to be exceeded more than 7 times a year	2010
		Annual mean of 18 µg/m3
Sulphur dioxide (SO2)		1 hour mean of 350 µg/m3, not to be exceeded more than 24 times a year	2004
		24 hour mean of 125 µg/m3, not to be exceeded more than 3 times a year
		15 minute mean of 266 µg/m3, not to be exceeded more than 35 times a year	2005

Emissions of Air Pollutants: 1990-2013

Index of air pollutant emissions (1990=100)

Why this measure is important

Air pollutants can negatively affect human and ecosystem health, with some pollutants such as PM₁₀^[45] being of particular concern to human health.

Background

Ricardo-AEA and Aether are contracted to provide estimates of air pollution emissions. These are published on the National Atmospheric Emissions Inventory.

Trend

Over the long term there have been reductions in emissions for all the pollutants in the inventory. Between 1990 and 2013, there have been decreases of 28% for ammonia, 53% per cent for PM₁₀, 66% for NMVOCs^[46], 67% for nitrogen oxides (NOx), 81% for carbon monoxide, 87% for sulphur dioxide and 99% for lead.

Factors affecting trend

Ammonia emissions have reduced through a combination of decreasing animal numbers and a decline in fertiliser use. Sulphur dioxide emissions fell following the move to gas fired power stations, the introduction of flue gas desulphurisation to coal-fired power stations and the closure of Cockenzie power station in 2013. Reductions in emissions of NOx and carbon monoxide are related to the need for new petrol cars to have 3 way catalysts installed and more recently the introduction of "Euro standards" for new cars. The decline in NOx emissions since 2007 is also linked to the power sector, as Boosted Over-Fire Air abatement systems were fitted which reduces NOx emissions formed during coal combustion. Reductions in NMVOCs are mainly the result of minimising fugitive emissions from sources such as oil loading and unloading operations. Historic reductions in lead emissions are due to the removal of lead in petrol.

Source: National Atmospheric Emissions Inventory | Metadata

Emissions of Sulphur Dioxide and Nitrogen Oxides from Large Combustion Plants: 1996-2014^[47]

Annual LCP emissions (thousand tonnes)

Why this measure is important

Sulphur dioxide (SO₂) and oxides of nitrogen (NOx) affect human health through respiratory damage, and ecosystem health through acidification. Oxides of sulphur, including SO₂, and NOx are released into the atmosphere through the combustion of fossil fuels.

Background

Data are obtained from the Large Combustion Plants Directive^[48] (LCPD) report, which is compiled for the United Kingdom LCPD submission to the European Commission.

Trend

In 2014, SO₂ emissions from large combustion plants decreased by 34% compared with 2013, mainly due to the closure of Cockenzie power station in March 2013^[49]. SO₂ emissions decreased by 82% between 1996 and 2014. The closure of Cockenzie reduced Cockenzie's NOx emissions by 80% between 2012 and 2013, but this was made up by increases from other sites and sectors. Overall, NOx emissions from large combustion plants decreased by 52% between 1996 and 2014. The 2014 SO₂ and NOx emissions are the lowest on record.

Factors affecting trend

Previous rises in emissions (for example, in 2006 and 2010) coincided with periods of cold weather which led to increased emissions from the electricity supply sector. This was in part due to increased electricity production at Longannet and the increased use of domestic coal, which has a higher sulphur content. Trends in emissions from Large Combustion Plants can also be affected by the relative prices of coal and gas.

Source: Scottish Environment Protection Agency | Metadata

Particulate (PM₁₀) Concentrations: 1997-2014^{[50],[51],[52]}

Annual mean concentration (µg/m³)

Why this measure is important

Particulate pollution can harm the human respiratory and cardiovascular systems, and is linked to asthma and mortality. Smaller particles are the most damaging as they can enter the bloodstream through the lungs. Current targets focus on particles less than 10µm in diameter (PM₁₀), the greatest source of which is combustion. Between 1990 and 2013, Scottish emissions of PM₁₀ fell by 53%^[53].

Background

Data are obtained from automatic air quality monitoring sites, which measure the concentrations of a range of pollutants at various sites across Scotland.

Trend

The Stage 2 annual mean objective was not met at 10 of 58 automatic monitoring sites with a data capture rate of greater than 75% in Scotland in 2014^[54], compared to 15 of 59 sites in 2013. One site in Aberdeen also failed to meet the Scottish daily mean objective. Edinburgh Salamander Street has not met the stage two Scottish annual mean objective since 2010.^[55]

Factors affecting trend

Changes in PM₁₀ concentrations depend on the levels of emissions from several different sources including domestic combustion and power generation. Recent reductions in PM₁₀ concentrations can be attributed to a reduction in the emissions from power generation, largely due to a switch from coal-fired energy generation to gas, which produces negligible PM₁₀ emissions.

Source: Scottish Air Quality Database | Metadata

Nitrogen Dioxide Concentrations: 1992-2014^{[56],[57],[58]}

Annual mean concentrations (µg/m³)

Why this measure is important

High concentrations of nitrogen dioxide (NO₂) can affect human health, particularly by causing inflammation of the airways. Ecosystem health is also damaged by NO₂ through its contribution to acid deposition, eutrophication (accelerated plant growth in water bodies caused by excess nutrients) and promotion of the formation of ground level ozone.

Background

Data are obtained from automatic air quality monitoring sites, which measure the concentrations of a range of pollutants at various sites across Scotland.

Trend

In 2014, the annual mean objective was not met at 10 of the 68 automatic monitoring sites with a data capture rate of greater than 75%^[59] in Scotland, compared to 14 of 70 sites in 2013. Those sites recording the highest annual mean concentrations were found next to busy roads, such as Glasgow Kerbside and Edinburgh St John's Road^[60]. The hourly mean objective was met at all automatic monitoring sites in Scotland in 2014.

Factors affecting trend

The main sources of nitrogen oxides (that are not produced naturally) are road transport, especially in urban areas, power generation and industry. Between 1990 and 2013, Scottish emissions of NOx are estimated to have decreased by 67%, due in part to the installation of catalytic converters in vehicles^[61].

Source: Scottish Air Quality Database | Metadata

Ground Level Ozone Concentrations: 1990-2014^[62],[63]

Number of days exceeding 100µg/m³ (maximum 8hr running mean)

Why this measure is important

Ozone in the stratosphere forms a layer that protects the Earth against harmful ultra-violet radiation, but tropospheric (ground level) ozone is a damaging oxidant. Exposure to high ozone concentrations can cause respiratory damage, and can affect vegetation by damaging leaves and reducing yields.

Background

Data are obtained from automatic air quality monitoring sites, which measure the concentrations of a range of pollutants at various sites across Scotland.

Trend

In 2014, the AQS objective was met at 8 of the 9 sites with a data capture greater than 75%^[64], compared to 5 of 8 sites in 2013. Strath Vaich failed to meet the AQS objective in 2014. Annual average ozone concentrations fluctuate from year-to-year and, as such, it is difficult to say if there is any overall trend.

Factors affecting trend

Ozone is formed from other pollutants that may be blown over from Europe. The most important man-made precursors are nitrogen oxides and volatile organic compounds produced by road transport, industrial processes and solvent use. Ozone concentrations also tend to be lower in urban areas where it is converted to nitrogen dioxide by reacting with nitrogen oxides.

Source: Scottish Air Quality Database | Metadata

Sensitive Habitats Exceeding Critical Loads for Acidification and Eutrophication: 1995-1997 to 2011-2013^[65],[66]

Percentage exceedance

Why this measure is important

Critical loads are thresholds above which the deposition of pollutants causing acidification (sulphur dioxide, nitrogen oxides and ammonia) and eutrophication (nitrogen oxides and ammonia) cause significant harm to the environment^[67]. Around 60% of Scotland's land area contains habitats sensitive to acid deposition and 55% to eutrophication.

Background

Critical loads for acidity and nutrient nitrogen are calculated using internationally agreed methods. These are then compared with deposition values to calculate critical load exceedances.

Trend

The area of sensitive habitats in Scotland exceeding critical loads for acidification fell from 68% in 1995-97 to 31% in 2011-13. While there was a period of increase between 2001-03 and 2005-07; overall, nutrient nitrogen exceedance fell from 59% to 41% between 1995-97 and 2011-13^[68].

Factors affecting trend

Changes in the area of sensitive habitats exceeding critical loads largely depend on changing emissions of pollutants; for instance, the reduction in acidity exceedance has been largely driven by a reduction in sulphur emissions. Changes were also made to the methodology for calculating depositions in 2001-03 and 2002-04, which means that depositions for earlier years may be underestimated.

Source: Centre for Ecology and Hydrology | Metadata