The Tropospheric Ozone Assessment Report (TOAR)  is an international activity under the International Global Atmospheric Chemistry project. It aims to assess the global distribution and trends of tropospheric ozone and to provide data that are useful for the analysis of ozone impacts on health, vegetation, and climate.

The TOAR data centre collects information about available tropospheric ozone data sets and provides access to the TOAR database, which compiles air quality monitoring data from thousands of sites around the world and forms the basis for much of TOAR’s trend assessment. The activities of the TOAR data centre are supervised by the TOAR-II steering committee and we will soon establish a TOAR data user forum to assist us in making these web pages as useful as possible for tropospheric ozone research and analyses.