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This section of the website allows you to choose a type of monitoring site, and then details for individual sites. Once you have chosen a site, its location will appear on the map above.

Choose a different type of monitoring site:
Hydocarbon Diffusion Tube sitesHydocarbon Diffusion Tube sites (8 Sites)
NO2 Diffusion Tube sitesNO2 Diffusion Tube sites (1018 Sites)
O3 Diffusion Tube sitesO3 Diffusion Tube sites (6 Sites)
SO2 Diffusion Tube sitesSO2 Diffusion Tube sites (9 Sites)

Non-Automatic Monitoring Sites in Wales

NO2 Diffusion Tube sites
in 2017

2015 2016 2017

Nitrogen dioxide

Date NO2 Units
04/01/2017  49* ugm-3
01/02/2017  51* ugm-3
01/03/2017  37* ugm-3
29/03/2017  40* ugm-3
31/05/2017  35* ugm-3
28/06/2017  31* ugm-3
02/08/2017  30* ugm-3
27/09/2017  36* ugm-3
01/11/2017  40* ugm-3
06/12/2017  50* ugm-3

Ratification Status:
» Red* - Provisional
» Green - Ratified

Use the buttons above to view data for years between 2015 and 2017

Further data and graphs may be downloaded here.

For more information on this monitoring data please contact this local authority at