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Sulphur Dioxide Concentrations: 1993-2007
Annual mean concentrations (µg/m 3)
Site 9 | 1993 | 1995 | 2000 | 2005 | 2006 | 2007 |
|---|
Number of 15-min means exceeding 266µg/m 3 |
|---|
Glasgow Centre | - | - | 0 | 0 | 0 | 0 |
|---|
Edinburgh 2 | 46 | 18 | 0 | 0 | 0 | 1 |
|---|
Grangemouth | - | - | - | 4 | 13 | 1 |
|---|
Annual mean concentration (µg/m 3) |
|---|
Glasgow Centre | - | - | 10 | 1 | 2 | 2 |
|---|
Edinburgh 2 | 22 | 20 | 6 | 3 | 3 | 3 |
|---|
Grangemouth | - | - | - | 7 | 7 | 7 |
|---|
The predominant source of atmospheric sulphur dioxide (SO 2) is the combustion of sulphur-containing fossil fuels, mainly coal and heavy oils. Annual urban SO 2 levels have fallen by around 75% since the 1956 Clean Air Act was introduced to combat smog.
High SO 2 levels over a short period of time are important as such incidents may cause respiratory difficulties. The Air Quality Strategy 4 objective for SO 2 stipulates that a 15-minute mean of 266µg/m 3 should not be exceeded more than 35 times a year (to be met by the end of 2005). This was achieved at all three sites in 2005, 2006 and 2007. However there is currently in place an Air Quality Management Area ( AQMA) at Grangemouth for the 15 minute objective, based on 2004 exceedences.
There are two further objectives, which are identical to the EU Air Quality Limit Values - a one hour mean of 350mg/m 3 not to be exceeded more than 24 times a year, and a 24 hour mean of 125mg/m 3 not to be exceeded more than 3 times a year. These have been achieved at all three sites.
Source: UK National Air Quality Archive
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