1. Council Directive 2008/50/EC on ambient air quality and cleaner air for Europe. European Parliament and European Council, 2008.
2. Council Directive 1999/30/EC relating to limit values for sulphur dioxide, nitrogen dioxide and oxides of nitrogen, particulate matter and lead in ambient air. European Council, 1999.
3. Council directive 80/779/EEC on air quality limit value for sulphur dioxide and suspended particles. European Council, 1980.
4. Council directive 89/427/EEC on air quality limit values and guide values for sulphur dioxide and suspended particulates. European Council, 1989.
5. Council directive 93/12/EEC relating to the sulphur of certain liquid fuels. European Council, 1993.