This special issue of Air Quality, Atmosphere and Health (AQAH) is the sixth and final in a series of special journal issues (Solomon 2010, 2011a, b, 2012; Solomon et al. 2011) associated with the 2010 Air Pollution and Heath Conference: Bridging the Gap between Sources and Health Outcomes (Solomon et al. 2012). The conference was based on a series of eight policy-relevant science questions (SQ1–SQ8) and one policy question (SQ9, see Table 1). The policy question integrated across the source-to-health effects continuum (NRC 1998). Nine sets of plenary speakers were asked to address the questions listed in Table 1 in their presentations at the conference and then to present a more comprehensive survey of the vast literature on their topics in the papers presented within this issue. The journal articles in this issue represent a “snap shot” in time and are not comprehensive reviews of the literature, but their strength is collectively drawn from the series, which clearly advances the science, and as indicated by the conference theme begins to “bridge the gap between air pollution sources and health outcomes.” Three science questions were not addressed (SQ2, SQ3, and SQ5), but information on these topics can be found in the series of EPA’s integrated science assessments (http://www.epa.gov/ncea/isa/).

Table 1 Policy-relevant science questions that were designed to begin to bridge the gap between sources and health outcomes and paper title and authors

While not as detailed and with a focus on what was presented at the conference, the conference overview (Solomon et al. 2012) addresses all nine questions and was prepared by a different group of world-renowned scientists than those who prepared journal articles for this issue. This allows the questions in Table 1 to be considered from different viewpoints, those of the authors and the readers, and provides a broader perspective on the overall science-to-health outcome issue. While the policy articles (SQ9) within this issue address aspects related to specific public and private sector viewpoints, the overview paper clearly delineates a series integrated policy-relevant insights providing a different perspective than those within this issue.