UK Air Quality Indicators Janet Dixon Air and Environment Quality Division, Department of Environment, food and Rural Affairs, UK

Air quality monitoring network

UK Air Pollution Index Used for providing a public summary of current and forecast air pollution 1-10 scale in 4 bands for 5 pollutants - ozone, PM 10, SO 2, NO 2, CO Produced for all 16 UK zones and largest 16 of the 28 UK agglomerations Levels reported = highest for any single pollutant Has health advice associated with each band Mainly driven by PM 10 and O 3 Further information:

UK Air Pollution Index O3O3 NO 2 PM 10 SO 2 CO µg m -3 (mg m -3 for CO) 8hr running mean or hourly mean Hourly mean24 hour running mean 15 minute mean 8 hour running mean Low (1-3) 0 – – 490 – 2650 – 11.5 Moderate (4-6) 100 – – – – – 17.3 High (7-9) 180 – – – – – 23.1 Very high (10) > 360> 764> 100> 1063> 23.2

UK Air Quality Headline Indicator UK Sustainable Development Strategy One of 15 headline indicators Developed in 1998, reviewed in 2002 Captures ‘acute’ air quality issues Counts number of days of moderate or higher (from AP Index) pollution for 5 ‘acute’ pollutants – ozone, PM 10, SO 2, NO 2, CO Does not correspond directly to UK Air Quality Strategy objectives

Headline indicator Maximum number of sites used is fixed Pre-1998 – up to 34 urban and 14 rural/remote 1998 – 34 urban and 14 rural/remote 2002 – 49 urban and 16 rural/remote To be included sites need minimum range of pollutants and data capture (>75%) Rural – at least O 3 Roadside/kerbside – at least PM 10 Other urban – at least O 3, PM 10 and SO 2 Fairly robust to changes in network Urban sites cover 26 of the 28 UK agglomerations

Urban sites Rural sites Final 2003 indicator

Causes of air pollution at urban sites total urban

particles sulphur dioxide Causes of air pollution at urban sites total urban

ozone particles sulphur dioxide Causes of air pollution at urban sites total urban

The main episodes driving 2003 Exceptionally hot summer – high ozone Particulate episodes in spring, including UK and European element Saharan dust storm Urban Rural high secondary particulates (SO 2 & NO 2 gas converted to particulate sulphates & nitrates)

PM10 NO 2 SO 2 Indicator picks up peaks – what about long-term trends? but….

….for ozone:

2003 was an exceptional year. Headline Indicator accurately reflects poor air quality in 2003 (but not every aspect). Headline indicator is currently being reviewed For the future: Conclusions long-term trend downwards for most pollutants. ozone increasing - global ozone precursor emissions, (?) global warming