Clean Air (European Union)
Reports and news on air quality issues.

Convention on Long-range Transboundary Air Pollution 
The official web page of the Convention has the text of the Convention and protocols as well as reports on implementation.

Open Journal of Air Pollution
This open access peer-reviewed publication is a quarterly journal that focuses on both scientific and policy aspects of air pollution.

State of Global Air
This website provides data and the report State of Global Air 2017.  The site is a collaboration between Health Effects Institute and Institute for Health Metrics and Evaluation.