EPA is releasing the Health and Environmental Research Online (HERO) database which provides access to the scientific studies used in making key regulatory decisions, including EPA’s periodic review of the National Ambient Air Quality Standards (NAAQS) for six major pollutants. 

The publically accessible HERO database provides an easy way to review the scientific literature behind EPA science assessments, which are used to support agency decision-making.  The database includes more than 300,000 scientific articles including the authors, titles, dates, and abstracts.  In addition, through a simple keyword search, anyone can see information from the articles that were used to develop specific risk assessments.
HERO includes peer-reviewed literature used by EPA to develop its Integrated Science Assessments (ISA) that feed into the NAAQS review.  It also includes references and data from the Integrated Risk Information System (IRIS), a database that supports critical agency policymaking for chemical regulation.
More information on HERO database: http://www.epa.gov/hero  
More information on IRIS: http://www.epa.gov/iris