Toxic Organic Micro Pollutants (TOMPs) Networks


The Toxic Organic Micro-Pollutants (TOMPs) network measures ambient air concentrations for a range of persistent organic pollutants (POPs) across the UK. The network was set up in 1991 with monitoring sites at urban and rural locations. The sites are Manchester (MAN), London (LON), Hazelrigg (HR) near Lancaster, Weybourne in Norfolk, High Muffles (HM) in North Yorkshire and Auchencorth Moss (AUCH) south of Edinburgh. MAN and LON sites have operated since 1991, HAZ since 1992 and HM since 1997. WEY was established in 2008 but replaced a nearby site at Stoke Ferry which started in 1997. AUCH was established in 2008. The network has provided over 25 years of continuous data and as such comprises a considerable and important dataset which can be used to provide estimates of the change in atmospheric concentrations over time and response to policy interventions.

Policy Context

The fate and behaviour of POPs in the environment has attracted considerable scientific and political interest, arising from concern over human exposure to these chemicals and their discovery in pristine environments far from source regions. The ability of certain POPs to undergo long range atmospheric transport (LRAT) has resulted in the negotiation of protocols for their reduction or elimination, and to reduce the risks to regional and global environments. These include the 1998 United Nations Economic Commission for Europe (UN/ECE) Protocol on Persistent Organic Pollutants made under the Convention on Long-Range Transboundary Air Pollution (, and the Stockholm Convention (SC) on POPs ( The UK is a signatory to both these instruments, and therefore has an on-going requirement to assess the extent of the presence of the listed POPs in the UK environment. The provision of long-term environmental monitoring data, such as that provided by TOMPs, is an important component of the UK’s obligations under these agreements.

What is measured?

The TOMPs network reports quarterly data for polychlorinated biphenyls (PCBs), polychlorinated-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polybrominated diphenyl ethers (PBDEs). The data comprises 37 PCB congeners, 4 co-planar PCB congeners, 10 furans congeners (PCDFs) and 7 dioxin congeners PCDDs, and 22 PBDE congeners. PBDEs were added to the list of POPs analysed in 2010. From late 2017 two additional flame retardants, decabrominated diphenyl ether (decaBDE) and hexabromocyclododecane (HBCDD) will be added to the list of POPs measured under the TOMPs network. These highly toxic and persistent species are ubiquitous in the environment, but are normally present at extremely low concentrations, the atmosphere being the principal route for their redistribution in the environment. More details on the POPs included in the network can be found on the SC website.

What is the purpose of the network?

The TOMPs network provides data to inform the public of air quality, and information to support the development of policy to protect the environment and human health. The specific aims of the TOMPs programme are:

  • To identify sources of a range of POPs in the UK’s atmosphere and to support emission inventories.
  • To quantify sources that are regarded as potentially significant.
  • To measure concentrations of POPs in ambient air in urban and rural locations in order to assess the relationship between source emissions and levels in the ambient atmosphere and human exposure.

Monitoring Methods

The TOMPs network uses modified Andersen GPS-1 high volume samplers to sample ambient air continuously over a 14 day sampling period. The samples are analysed using a range of sophisticated chemical analysis techniques which include gas chromatography coupled with high-resolution mass spectrometry for the PCDD/Fs and for those PCBs with dioxin-like effects and low-resolution mass spectrometry for the other PCBs and PBDEs including decaBDE. HBCDD is analysed routinely by GCMS, but additional isomer data provided by LCMS (QqQ).

View data for sites in this network

Data can be downloaded from the Data Selector page of this website and UNEP Global Monitoring Plan on Persistent Organic Pollutants

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