e-Digest Statistics about: Air Quality
Monitoring
Air quality monitoring networks are structured to meet specific objectives, and the number and location of monitoring sites are reviewed periodically to ensure that they provide a representative and cost effective coverage of the UK. There are basically two types of monitoring:
- continuous automatic monitoring which gives instantaneous measurements of air pollution concentrations
- monitoring using non-automatic equipment which provides concentration measurements over longer averaging periods, typically daily, weekly or monthly.
Selected summary tables from these networks are included on this web site. More comprehensive data from all the networks are available from the Air Quality Archive, along with details of and reports from the related Defra scientific research programme.
Automatic networks
Defra co-ordinates the funding of two automated monitoring networks on behalf of the Government and the devolved administrations - the Automatic Urban and Rural Network (AURN) and the Hydrocarbon Network. The AURN was formed of the Automatic Urban network (AUN) and the Automatic Rural Network (ARN), which were combined into a single monitoring programme in October 2002. Figure 1 shows the location of the automatic network sites at March 2006. The number of sites increased from 74 at the end of 1996 to 120 by March 2006. The increase was mainly in urban sites to provide more comprehensive coverage on air quality in UK cities. SO2, NOx, CO, O3 and particulate matter (PM10) are measured at a variety of urban locations, including urban background locations representative of population exposure for significant periods, and "hotspot" monitoring at urban kerbsides and in the vicinity of industrial sources. Rural sites mainly monitor O3 but also SO2, NOx and PM10 in some cases. The sites in the Hydrocarbon Network monitor 25 volatile organic compounds including benzene, 1,3-butadiene and O3 precursors at urban roadside, urban background and rural locations across the country. Further details about sites can be found on the Air Quality Archive. Quality control arrangements ensure that measurement precision standards of at least ±10 µg/m³ for SO2, ±8 µg/m³ NOx and O3, ±0.5mg/m³ for CO and ±4µg/m³ for PM10 are achieved at automatic monitoring sites.
Hourly data on ambient SO2, NOx, O3, CO and particulate matter concentrations are used to provide air pollution information to the public produce hourly pollutant concentrations. Data is collected from individual sites and posted directly online for real time information either online or via the free air pollution telephone line (0800-556677), TELETEXT (page 156), the Air Quality Information Archive, newspapers and broadcast bulletins. The Site Information Archive gives detailed information for each site presently in operation.
| At present (July 2006) there are 124 automatic sites in operation in the UK. The following table breaks this total down by location type and pollutant | |||||||||
| Pollutant type | |||||||||
| Location type |
NO2 |
SO2 |
PM10 |
PM2.5 |
CO |
O3 |
Benzene |
1,3-Butadiene |
Total |
| Kerbside |
3 |
1 |
3 |
1 |
2 |
1 |
2 |
2 |
3 |
| Roadside |
20 |
7 |
4 |
0 |
17 |
2 |
0 |
0 |
20 |
| Suburban |
8 |
5 |
5 |
0 |
3 |
9 |
1 |
1 |
11 |
| Urban background |
34 |
30 |
23 |
0 |
28 |
29 |
0 |
0 |
38 |
| Urban centre |
25 |
23 |
20 |
1 |
22 |
25 |
1 |
1 |
25 |
| Urban industrial |
5 |
4 |
4 |
0 |
4 |
2 |
0 |
0 |
6 |
| Airport |
1 |
0 |
1 |
0 |
1 |
1 |
0 |
0 |
1 |
| Rural |
14 |
6 |
3 |
2 |
2 |
18 |
1 |
1 |
18 |
| Remote |
0 |
0 |
1 |
0 |
0 |
2 |
0 |
0 |
2 |
| Total |
110 |
76 |
64 |
4 |
79 |
89 |
5 |
5 |
124 |
Non-automatic networks
Measurements of daily SO2 and black smoke concentrations in urban areas are currently made through the UK Smoke and Sulphur Dioxide Network, which serves two purposes. Firstly, the network is intended to provide a long-term database of smoke and SO2 measurements to assess trends in concentration and spatial distribution. For this purpose a core subset of sites is used to provide a representative sample of monitoring locations in major population centres throughout the UK. Secondly, the Network monitors compliance with the relevant EC Directives on sulphur dioxide and suspended particulate matter.
There are also various other networks in operation - for example, the non-automatic Hydrocarbon Network (35 sites monitoring benzene at urban background and roadside locations), the Toxic Organic Micropollutants (TOMPS) Network, the Nitrogen Dioxide Diffusion Tube Network, the Lead, Multi-Element Network, the Acid Deposition Network and the Rural Sulphur Dioxide Network. The data for these can be accessed from the Air Quality Archive.
Further Information:
- Data Tables:
- 1 Air pollutant types (including greenhouse gases) March 2006 XLS
- Fig 1 Air quality automatic monitoring sites in operation March 2006 XLS
- Internet Links:
- National Air Quality Information Archive
Your questions and comments about information presented on this page are welcome. Contact information and Email . Copyright of data and/or information presented or attached in this document may not reside solely with this Department. Please see guidance on Copyright.
Page last modified: 19 October 2006
Page published: 10 September 2003