Key Scottish Environment Statistics 2014

Air Quality

Particulate (PM₁₀) Concentrations^[1],[2],[3]: 1993-2013

Annual mean concentration (µg/m³)

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 through the lungs and into the bloodstream. Current targets focus on particles less than 10µm in diameter (PM₁₀), the greatest source of which is combustion. Between 1990 and 2011, Scottish emissions of PM₁₀ fell by 58%.^[4]

The Air Quality Strategy (AQS)^[5] objectives for PM₁₀ come in two stages. Stage 1 sets objectives of: a 24 hour mean of 50μg/m³ not to be exceeded more than 35 times a year, and an annual mean of 40μg/m³ (both were to be achieved by the end of 2004). Stage 2 sets longer term objectives of: a 24 hour mean of 50μg/m³ not to be exceeded more than 7 times a year, and an annual mean of 18μg/m³ (both to be achieved by the end of 2010).

In 2013, the Stage 1 objectives were met at all of the automatic monitoring sites.^[6] The Stage 2 annual mean objective was not met at 15 of 59 automatic monitoring sites in Scotland in 2013. Two sites also failed to meet the Scottish daily mean objective. Edinburgh Salamander Street has not met the stage two Scottish annual mean objective since 2010.

Through analysis of modelled background PM_2.5 concentrations (particles less than 2.5 µm in diameter) it is estimated that the effects on annual mortality in 2010 in Scotland were over 2000 deaths and over 22,000 associated life-years lost.^[7]

Currently there are 31 Air Quality Management Areas (AQMAs)^[8] in Scotland. Nine of these have been declared solely for PM₁₀ and a further 11 for both PM₁₀ and nitrogen dioxide (NO₂). Ten of the remaining AQMAs are for NO₂ only, one is for sulphur dioxide (SO₂). All except the SO₂ AQMA have been declared on the basis of emissions from transport sources.

Source: Scottish Air Quality Database / Metadata

Nitrogen Dioxide Concentrations^[1],[9],[10]: 1992-2013

Annual mean concentrations (µg/m³)

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

Between 1990 and 2011, Scottish emissions of nitrogen oxides fell by 65%.^[4] Road transport was responsible for 29% of the emissions of nitrogen oxides in 2011.

The UK Air Quality Strategy^[5] objectives for NO₂ (to be met by the end of 2005) are an annual mean of 40µg/m³ and an hourly mean of 200µg/m³ not to be exceeded more than 18 times a year. In 2013, the first objective was not met at 14 of the 70 automatic monitoring sites^[11] in Scotland. Those sites recording the highest annual mean concentrations were found next to busy roads, such as Edinburgh Queensferry Road and Glasgow Kerbside. The second objective was met at all but 4 automatic monitoring sites; Dundee Lochee Road and Edinburgh St John's Road were among those that failed.

Of the 31 Air Quality Management Areas^[8] in Scotland, 10 have been declared solely for NO₂ and a further 11 for both NO₂ and PM_10.

Source: Scottish Air Quality Database / Metadata

Ground Level Ozone Concentrations^[1]: 1990-2013

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

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 affects vegetation by damaging leaves and reducing yields.

Ozone is formed by a slow, complicated series of reactions 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 tend to be lower in urban areas where it is converted to nitrogen dioxide by reacting with nitrogen oxides.

The Air Quality Strategy^[5] objective for ground level ozone concentration (to be met by 2005) states that the maximum daily concentration (measured as an 8-hour running mean) of 100µg/m³ should not be exceeded more than 10 days per year. In 2013, this objective was met at 5 of the 8 sites with a data capture greater than 75%.^[12] Strath Vaich, Eskdalemuir and Bush Estate all failed to meet the AQS objective in 2013. All 3 sites, which are either rural or remote, regularly exceed the AQS objective.

Source: Scottish Air Quality Database / Metadata

Emissions of Sulphur Dioxide and Nitrogen Oxides from Large Combustion Plants^[13]: 1996-2013

Annual LCP emissions (thousand tonnes)

Sulphur dioxide (SO₂) and oxides of nitrogen (NO_x) affect human health through respiratory damage, and ecosystem health through acidification. SO₂ and NO_x are released into the atmosphere through the combustion of fossil fuels. In 2011, large combustion plants (LCPs) accounted for 71% of the SO₂ emissions and 25% of NO_x emissions in Scotland.^[4] In 2013 there were 54 LCPs in Scotland, down from 57 in 2011.

The Large Combustion Plants Directive (LCPD, which has now been incorporated into the Industrial Emissions Directive (2010/75/EC)^[14]) called for a 60% reduction in LCP SO₂ emissions by 2003 and a 30% reduction in LCP NO_x emissions by 1998, from a 1980 baseline. By 2002, total UK emissions of SO₂ were 79% below 1980 levels, and 91% below 1980 levels in 2012. In 1998, total UK emissions of NO_x were 25% below 1980 levels, and 60% below 1980 levels in 2012.^[15] The Large Combustion Plants Directive has now been superseded by the Industrial Emissions Directive 2010/75/EU, which was transposed into Scottish law by the Pollution Prevention and Control (Scotland) Regulations 2012.

In Scotland, SO₂ emissions from the electricity supply industry fell between 1996 and 1999, but there were rises, particularly in 2000, 2006 and 2010. These rises were due to the cold weather and increased use of coal-fired power stations, at times necessary to offset the reduced capacity of the nuclear sector because of refurbishment work but also affected by the price of coal versus gas. In 2013, SO₂ emissions from large combustion plants decreased by 32% compared with 2012, mainly due to the closure of Cockenzie power station in January 2013.^[16]

NO_x emissions from large combustion plants decreased by 36% between 1996 and 2010. This was followed by a 22% reduction between 2010 and 2011, in part due to a reduction in Cockenzie's emissions. Emissions of NO_x were the lowest on record in 2011 before increasing by 9% in 2012 and subsequently decreasing by 6% in 2013.

Source: Scottish Environment Protection Agency / Metadata

Sensitive Habitats Exceeding Critical Loads for Acidification and Eutrophication^[17]: 1995-1997 to 2010-2012

Percentage exceedance

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.^[18] The pollutants mainly come from industry, transport and agriculture.

Around 60% of Scotland's land area contains habitats sensitive to acid deposition and 55% to eutrophication. The area of sensitive habitats in Scotland exceeding critical loads for acidification fell from 68% in 1995-1997 to 33% in 2010-2012, primarily due to reductions in sulphur emissions. This included a 16% reduction in acidity exceedance between 2004-06 and 2010-12. Following a period of increase between 2001-2003 and 2005-2007, nutrient nitrogen exceedance decreased by 13% between 2005-2007 and 2010-2012. Overall, nutrient nitrogen exceedance fell from 59% to 45% in the period 1995-1997 to 2010-2012.^[19]

The EU National Emissions Ceiling Directive sets limits for emissions of ammonia, nitrogen oxides, sulphur dioxide and volatile organic compounds (VOCs) to be achieved by 2010. According to data released from the European Environment Agency (EEA), the UK is meeting these targets. The Gothenburg Protocol (United Nations Economic Commission for Europe, 1999) also sets ceilings for these emissions. The UK ratified the Protocol in 2005.

Source: Centre for Ecology and Hydrology / Metadata