The State and Territorial Air Pollution Program Administrators (STAPPA) and the Association of Local Air Pollution Control Officials (ALAPCO) are national associations representing air pollution control agencies in the 54 U.S. states/territories and over 150 major metropolitan areas. Site has information and links.

Features information on the causes and effects of pollution. Includes forecast bulletin, 24 hour summaries and articles.

Up to date information on air quality issues in Canada. Including environmental law and policy, motor vehicle emissions and industrial sources of pollution. Maintained by students at the Environment Law Centre, University of Victoria.

Focus is air quality and the mechanics of air pollution. Information about publications, training courses, conferences, and seminars.

Describes the mandatory vehicle emissions testing program in the Denver-Boulder area of Colorado, including maps to emissions stations, testing requirements, help for failing vehicles and tips to keep from becoming a gross polluter.

The site contains vehicle emissions databases and reports remotely collected from in-use vehicles since 1987 from around the world. Data sets include cars, light-trucks, heavy-duty trucks, jet aircraft, locomotives and snowmobiles.

Information on compliance technologies, vendors, and case studies for toxic air pollutants (as defined in U.S. regulations).

Provides technical assessments on ozone and other problems of air quality in Illinois, Indiana, Michigan, and Wisconsin. Data and modeling reports available online.

A division of RIVM, National Institute of Public Health and the Environment. Up-to-date, hourly information about air quality in The Netherlands.

Air Quality monitoring networks of London, Bedfordshire, Kent and Hertfordshire in the UK. Near realtime data is available from the site.