First international protocol to set binding emission limits for cadmium, lead, and mercury under the CLRTAP framework.
Key Facts
- Adoption date
- 24 June 1998
- Signatories (as of 2016)
- 35
- Parties (as of 2016)
- 33
- EU cadmium reduction (2005–2023)
- 43%
- EU mercury reduction (2005–2023)
- 57%
- EU lead reduction (2005–2023)
- 46%
By the Numbers
Location
Cause → Event → Consequence
Industrial processes, fossil fuel combustion, and non-ferrous metal production released cadmium, lead, and mercury into the atmosphere. These heavy metals were capable of long-range transboundary transport and posed serious health risks, including cancer and chronic respiratory disease, prompting the need for coordinated international controls.
The Protocol on Heavy Metals was adopted in Aarhus, Denmark, on 24 June 1998 as a protocol to the Convention on Long-Range Transboundary Air Pollution. It set specific emission limit values and control measures for cadmium, lead, and mercury across key industrial sectors. Amendments agreed in 2012 sought to introduce stricter limits but had not yet entered into force.
The protocol contributed to measurable reductions in heavy metal emissions across EU member states between 2005 and 2023. A dedicated Task Force on Heavy Metals was established to monitor and assess its effectiveness, later merging into a broader techno-economic task force in 2014 to evaluate a wider range of air pollutant reduction strategies.
Political Outcome
Protocol adopted with binding emission limits for cadmium, lead, and mercury; 35 signatories and 33 parties as of 2016; 2012 amendments agreed but not yet in force.