NO₂ Diffusion Tube Network (1993-2005)

Details of the Network

The files accessible from this page detail the data from the Department for Environment, Food and Rural Affairs' UK Nitrogen Dioxide Network, which operated from 1993 to 2005. The network was a co-operative effort between DEFRA and Local Authorities within the United Kingdom to map spatial and temporal trends in NO₂ concentrations throughout the UK. The programme was co-ordinated on behalf of DEFRA by Netcen.

Monitoring of NO₂ with diffusion tubes took place at urban locations which are defined below:

• Road side: 1-5m from a busy road. Formerly named 'Kerbside' (K). One site during years up to and including 2000, 2 sites from 2001 to 2005.
• Intermediate: 20-30m from the same or an equivalent road. This category is ceased, as of December 2000. 1 site per local authority in previous.
• Background: >50m from any busy road (2 Sites per local authority).

Details of the monitoring sites.

NO₂ Diffusion Tube Calendar

Each tube was exposed for a period of one month. The year was divided into 12 pollution 'months', each consisting of 4 or 5 whole weeks. Each month began on a Tuesday, to minimise disruption due to public holidays. For details of each year's calendar of exposure periods, see below.

The exposure periods of diffusion tubes varied from year to year. The calendar of exposure for each year is given on the right:

The site operators were asked to ensure that their tubes were changed each month, within +/- 2 days of the date specified.

The NO₂ ceased operation at the end of 2005; information on spatial distribution and trends are now more effectively provided by the AURN and by modelling.

However, NO₂ diffusion tubes remain an important tool for Local Air Quality Monitoring, and Netcen provide a range of support services to assist Local Authorities making use of them. For more information, please contact Netcen at 0870 190 6050. Data from Local Authority sites can be downloaded from this web site.