The majority of data sets shown on this portal are not directly curated by TOAR and we assume no responsibility for the correctness of any of the information provided here. The TOAR data centre does not store duplicates of these data, but only offers links to web pages with data descriptions, data access points, and REST APIs (i.e. machine readable interfaces). It also includes contact information and data license terms where available.

The only data that are physically stored at the TOAR data centre are the surface air quality monitoring observations, where we have built a PostGIS database (i.e. the TOAR database) to collect and harmonize extensive metadata on monitoring sites and air quality time series. The vast majority of these data were obtained from direct interactions with environmental and research agencies around the world. Even though many of these data sets are also freely available for download, access to these data is not always straightforward, data formats vary substantially, and metadata information is often missing or incomplete. These aspects are harmonized upon integration of these data into the TOAR database. We strive to maintain direct contact to the data providers in order to stay informed about changes to the data and to report any issues back to them, which we identify. Nevertheless, no data collection is perfect, and we must point out that we provide the data as is without any guarantee. We try our best to ensure the highest possible data quality, and you can help this effort by sending us feedback if you spot any issues in the TOAR database.