The Council Directive 2008/50/EC on Ambient Air Quality and Cleaner Air for Europe requires member states to assess ambient air for levels of a number of defined pollutants. The directive sets out limit values which member states are required to meet. The limit values specify both the level the pollutants must be kept below, and the time over which data should be averaged. Limit values with averaging times of less than or equal to 24 hours, and which have been or are being exceeded in London are detailed below:
NO2 hourly mean of 200 ug/m3 (not to be exceeded more than 18 times per year)
24 hour mean (PM10 of 50 ug/m3, (not be exceeded more than 35 times per year).
The following table indicates for monitoring sites in London the number of days per year where an exceedance of either of the above detailed limit values has occurred, for all years between 2005 and 2008 inclusive.
Site Code Site Name Year Days Exceedence of EU Limit Values A30 London A3 Roadside 2005 2 CD1 Camden Kerbside 2005 6 HS5 Brentford Roadside 2005 7 KC2 London Cromwell Road 2 2005 2 MY1 London Marylebone Road 2005 156 Total 2005 173 MY1 London Marylebone Road 2006 150 Total 2006 150 CD1 Camden Kerbside 2007 21 HG1 Haringey Roadside 2007 1 HK4 London Hackney 2007 3 HS5 Brentford Roadside 2007 5 MY1 London Marylebone Road 2007 123 total 2007 153 CD1 Camden Kerbside 2008 27 HS5 Brentford Roadside 2008 23 MY1 London Marylebone Road 2008 174 Total 2008 224
The following should be noted in conjunction with the table.
The numbers presented represent a combination of both the above limit values.
If a single day occurred where there was an exceedance of both the above limit values, it has only been counted once, i.e. the total number of days per year exceeding at each site cannot exceed 365.
For the hourly mean N02 limit value, the number presented represents a single hour in the day above 200 microgrammes/m3 (where the total number of hourly means in excess of 200 microgrammes/m3 at that site was greater than 18 in the year). This counts as one day where an exceedance occurred, even though there may have been several hours above this concentration in the 24 hour period. Only hours in excess of the 18 allowed per year have been counted as contributing to the exceedance.
For the daily mean PM10 limit value, the total number of days represents the number of days where 24 hour mean concentrations were in excess of 50 microgrammes/m3, with the first 35 allowed occurrences subtracted.
Therefore the days counted include only those which are above the 35 days per year allowed, or 18 hours per year allowed, as defined by the limit values.
Data have only been reported for sites with more than 90 per cent. data capture.
Under EU legislation, the UK is required to assess ambient air for levels of nitrogen dioxide (NO2), and to report to the European Commission on an annual basis. Detailed reports on the assessments are available from the Air Quality Archive (www.airquality.co.uk). Nitrogen dioxide monitoring is undertaken in London at a number of sites for this purpose in accordance with the criteria in the Council Directive 2008/50/EC on Ambient Air Quality and Cleaner Air for Europe.
Annual mean NO2 monitoring data are displayed in the table for sites within London for years since 2005. Data are only displayed for sites where data capture for that year was greater than 90 per cent.
Site code Site name Year Annual mean NO2 ( microgrammes/m-3) A30 London A3 Roadside 2005 61 BL0 London Bloomsbury 2005 57 BX1 London Bexley 2005 36 BY7 Bromley Roadside 2005 49 HG1 Haringey Roadside 2005 42 HG2 London Haringey 2005 34 HI0 London Hillingdon 2005 45 HK4 London Hackney 2005 49 HS5 Brentford Roadside 2005 49 KC1 London N. Kensington 2005 40 KC2 London Cromwell Road 2 2005 79 LH0 London Harlington 2005 38 LW1 London Lewisham 2005 51 MY1 London Marylebone Road 2005 112 SK1 London Southwark 2005 49 SK2 Southwark Roadside 2005 60 TD0 London Teddington 2005 25 TH2 Tower Hamlets Roadside 2005 61 WA2 London Wandsworth 2005 54 A30 London A3 Roadside 2006 59 BL0 London Bloomsbury 2006 57 BT1 London Brent 2006 30 BX1 London Bexley 2006 36 CD1 Camden Kerbside 2006 71 GR4 London Eltham 2006 30 HG2 London Haringey 2006 33 HI0 London Hillingdon 2006 49 KC1 London N. Kensington 2006 38 KC2 London Cromwell Road 2 2006 83 LH0 London Harlington 2006 37 LW1 London Lewisham 2006 54 MY1 London Marylebone Road 2006 110 TD0 London Teddington 2006 23 TH2 Tower Hamlets Roadside 2006 60 WA2 London Wandsworth 2006 51 WM0 London Westminster 2006 50 BT1 London Brent 2007 32 BX1 London Bexley 2007 34 BY7 Bromley Roadside 2007 47 CD1 Camden Kerbside 2007 77 GR4 London Eltham 2007 30 HG1 Haringey Roadside 2007 42 HG2 London Haringey 2007 32 HI0 London Hillingdon 2007 45 HK4 London Hackney 2007 49 HS5 Brentford Roadside 2007 63 KC1 London N. Kensington 2007 39 KC2 London Cromwell Road 2 2007 71 LH0 London Harlington 2007 37 LW1 London Lewisham 2007 53 MY1 London Marylebone Road 2007 102 SK1 London Southwark 2007 44 TD0 London Teddington 2007 28 BL0 London Bloomsbury 2008 55 BT1 London Brent 2008 33 BX1 London Bexley 2008 33 BY7 Bromley Roadside 2008 45 CD1 Camden Kerbside 2008 76 GR4 London Eltham 2008 26 HG1 Haringey Roadside 2008 37 HG2 London Haringey 2008 32 HK4 London Hackney 2008 51 HS5 Brentford Roadside 2008 58 KC1 London N. Kensington 2008 33 LH0 London Harlington 2008 35 LW1 London Lewisham 2008 52 MY1 London Marylebone Road 2008 115 SK1 London Southwark 2008 47 TD0 London Teddington 2008 25 TH2 Tower Hamlets Roadside 2008 63 WM0 London Westminster 2008 40
All combustion processes in air produce oxides of nitrogen (NOx). Nitrogen dioxide (NO2) and nitric acid (NO) are both oxides of nitrogen and are referred to as NOx. Road transport is the main source. At high levels NO2 causes inflammation of the airways. Long-term exposure may affect lung function and respiratory symptoms.
London is currently exceeding the EU Limit Value of 40 microgrammes/m3 and is not likely to meet this value by the attainment date of 2010. The Council Directive 2008/50/EC on Ambient Air Quality and Cleaner Air for Europe provides for member states to submit plans to the European Commission to postpone the compliance deadline for meeting the limit value for nitrogen dioxide from 2010 to 2015. The UK Government expect to submit such a plan to the Commission in 2010 following consultation early next year.