The AQS Data Mart is a database containing all of the information from the AQS system. The AQS Data Mart was built as a storehouse of air quality information that allows users to make queries of unlimited quantities of data. The main AQS system must maintain constant readiness to accept data, and thus is limited in the number and size of queries it can respond to. The Data Mart has no such limitation, other than the 'wall clock' time it takes for a query to run. The Data Mart also includes information from the EPA's substance and facility registry systems to allow for cross-media integration. Starting in the summer of 2007, it will also contain information from AirNow (the real time air quality reporting system) that participating agencies allow to be shared with the public.