Our work

Heavy metals and persistent organic pollutants

Heavy metals and persistent organic pollutants are part of the group of pollutants that is responsible for large-scale transboundary air pollution. TNO's International Emission Monitoring team is playing a major role in substantiating and supporting policy intended to reduce this pollution.

Dutch and European policy in this area is laid down in De Convention on Long-Range Transboundary Air Pollution (CLRTAP; 1979). The Convention is supplemented by a number of protocols, including: The UNECE Protocol on Heavy Metals (1998). This protocol aims to reduce emissions of cadmium, mercury and lead as well as to reduce emissions of other heavy metals (arsenic, chrome, copper; nickel, selenium and zinc). Heavy metals are released when fossil fuels are burned and during industrial processes. They are also present in products (brake linings, batteries). The UNECE Protocol on Persistent Organic Pollutants (POPs) (1998). Among other things, this protocol provides a ban and/or far-reaching restriction on 13 POPs and requires reduced emissions of dioxins, furans, polycyclical aromatic hydrocarbons (PAHs) and hexachlorobenzene (HCB). The most significant sources of POPs are industry, consumers (inc. open hearths), transport and agriculture. POPs can be divided into three groups:

  • Pesticides (inc. DDT);
  • Industrial chemicals (inc. PCBs);
  • Pollutants released during combustion (PAHs, dioxins).

The policy development and protocol negotiations are supported by scientific research in the field of air modelling and monitoring, effects and integrated modelling. TNO has recently compiled emission inventories of heavy metals and POPs in Europe, including future projections (2010-2020). The studies are a continuation of earlier emission inventories carried out TNO before 1990 (Berdowski et al., 1997) and form the basis for an evaluation of the effectiveness of the UNECE protocols; they have been presented to various policy-making committees such as the EMEP Steering body and the UNECE Working Group on strategies and review. By means of an analysis of the remaining causes of emissions, suggestions can be made for tightening protocols.

Emission inventories

Emission maps can be drawn up based on the emission inventories. These maps serve as input for the predictive modelling of the deposition of heavy metals and POPs. Projects:
As well as the above-mentioned studies covering the UNECE Europe area, inventories and analyses are also performed for small sub-areas. As a rule, the latter involve more thorough analysis. Examples are:

  • Uncertainties in dioxin emission estimates for Central Europe;
  • Brake-lining wear as a source of diffuse copper pollution;
  • Heavy metal levels in fuels.

Dr. ir. Hugo Denier van der Gon


Dr. ir. Hugo Denier van der Gon


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