51 countries of the United Nations Economic Commission for Europe (UNECE) are parties to the convention for cooperation and measures to limit and gradually reduce air pollution, this including EU Member States, Canada, the United States and several Central Asian countries.
Since its signature in 1979, eight specific protocols have been attached to the CPATLD (Convention on long-range transboundary air pollution).
The 1999 Protocol to reduce acidification, eutrophication and tropospheric ozone also known as the "Gothenburg Protocol", was approved by the Council, on behalf of the EU. It has been transposed into EU law mainly by the 2001 NEC Directive and the 2001 Directive on emissions from large combustion plants as coal-fired power plants, cement & glass plants, hazardous material incinerators, waste incinerators,… The proposed amendment to the 1999 Protocol sets out new national emission reduction commitments as of 2020. It covers four air pollutants: sulphur (mainly sulphur dioxide), nitrogen oxides, ammonia and compounds. volatile organic compounds (VOCs) other than methane, as well as particulate matter.