In February 2005, ministers from 60 countries and the European Commission met in Brussels, Belgium to endorse the 10-year plan for a Global Earth Observation System of Systems (GEOSS) prepared by the Group on Earth Observations (GEO), a partnership of nations and international organizations. This multinational project integrates surface-based, airborne, and space-based remote sensing and in-situ networks to improve knowledge of the environmental factors that affect human health and well-being. Shortly thereafter, in April 2005, the US Government released its Strategic Plan for the US Integrated Earth Observation System (IEOS), which provides a framework for US contributions to the GEOSS, and also strives to meet requirements for high-quality data on the state of the Earth as a basis for policy and decision-making and to provide more accurate exposure assessments for the health and environment research communities. The plan was drafted by the US Group on Earth Observations (USGEO), an interagency subcommittee that reports to the National Science and Technology Council's Committee on Environment and Natural Resources. Both the GEOSS and the IEOS emphasize consideration of user needs in the development of Earth observation data architectures. Toward this end, the National Institute of Environmental Health Sciences (NIEHS) and the Environmental Protection Agency (EPA) co-sponsored a workshop that united 40 health and Earth observation scientists in a dialogue over data-user requirements. The results of the workshop titled Integrated Earth Observations: Application to Air Quality and Human Health, which was held at NIEHS on 1-2 August 2005, are described in this report. Experts in meteorology, atmospheric chemistry, satellite engineering, and ground-based air measurements represented the Earth observation sciences. Health scientists provided expertise in epidemiology, exposure assessment, biostatistics, spatial statistics, clinical research, toxicology, informatics, and modeling.