The “Clean Air Blue Paper” is a continuation of the effort that builds upon the understanding of PM2.5 (Particulate Matter 2.5: PM2.5), which was initially discussed in the previously published “Clean Air White Paper”. In this sequential concept paper, the research team aims to impart an in- depth knowledge of the impacts of air pollution to create awareness on its damage to Thai society. In writing this report, the research team undertook an in-depth review of research published in internationally accepted academic journals, as well as, conducted field visits, in-depth interviews and held focus group meetings with diverse stakeholders.