Air pollution was initially only regulated by national legislation. But as the transboundary nature of air pollution has become apparent, a number of international agreements, conventions and guidelines have been adopted, with the aim of regulating emissions of air pollutants.
According to a recent UNEP study around two-thirds of all countries worldwide had some sort of air quality standard in 2021. Besides the fact that ambient air quality is not legally protected in a third of all countries, it should be noted that there is a great variation in stringency between different national standards.
The World Health Organization (WHO) air quality guidleines have exitsted since the 1970s, and have been updated regulary since then. The latest version of the global guidelines were published in 2021. They offer quantitative health-based recommendations for air quality management, expressed as long or short-term concentrations for several key air pollutants. These guidelines are not legally binding, but they provide states with an evidence-informed tool that they can use to inform legislation and policy, and ultimately to help reduce levels of air pollutants and their related enormous health burden.
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.
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.