At the international level there are a number of agreements, or conventions, that have been reached with the aim of regulating emissions of air pollutants.
Until the early nineties, European Union policy regarding air pollution tended to be fragmented. Since the mid-1990s, efforts have been more strategically oriented. A directive establishing national emission ceilings (NEC) for four air pollutants was adopted in 2001. That same year also saw the launch of the Clean Air for Europe Programme (CAFE), which in 2005 lead to the adoption of a Thematic Strategy on air pollution. In 2008 a new air quality directive was adopted, and in 2010 a new directive on industrial emissions of air pollutants was agreed. 2013 was named “the EU year of air”, and at the very end of that year the Commission presented a clean air policy package, including a proposal for a revised NEC directive. After discussions in the Parliament and the Council, a new NEC directive was adopted in December 2016, setting legally binding emission reduction commitments for the member states' emissions of five important air pollutants, to be achieved by 2030.
The Convention on Long-range Transboundary Air Pollution (the LRTAP Convention) was signed by some 30 countries in Europe and North America in 1979. It currently has 51 signatories and has been extended by eight protocols, the most recent being the so-called Gothenburg Protocol signed in 1999, which entered into force in 2005, and was revised in 2012.
For a long time international shipping was a more or less unregulated source of air pollution. While pollutant emissions from land-based sources were gradually coming down after the 1980s, those from shipping continued increasing. An air pollution annex to the International Maritime Organization’s MARPOL Convention was agreed in 1997, entered into force in May 2005, and was revised and strengthened in 2008. Within the EU, some ship emissions are regulated by the sulphur-in-fuels directive, which was revised and strengthened in 2012.