title: Global air quality monitoring: Trends and levels of sulphur dioxide and suspended particulate matter in selected urban areas.
abstract: An overview is presented of the development and ongoing activities of the WHO/UNEP air quality monitoring project. The project started in 1973 and is part of the Global Environmental Monitoring System. An analysis of the sulphur dioxide and suspended particulate matter is also included. The results show that the annual mean concentration for sulphur dioxide has decreased since 1973; for suspended particulate matter, however, a gradual increase is observed since 1976.
authors.affiliation: Division of Environmental Health, World Health Organization, Geneva, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: De Koning
authors.forename: J
authors.initials: J
authors.lastname: Kretzschmar
authors.forename: G
authors.initials: G
authors.lastname: Akland