The World Health Organization (WHO) defines health impact assessment (HIA) as “a combination of procedures, methods and tools by which a policy, programme or project may be judged as to its potential effects on the health of a population, and the distribution of those effects within the population”. HIAs have become increasingly prominent in the public health sector. For more than 20 years, HIAs of air pollution have been conducted in Switzerland to estimate the external costs of traffic. The last major methodological update regarding epidemiological methods was made for the year of analysis 2010 (published in 2014), while the next update is expected for 2021. Air pollution health research has been considerably developed in the last years, which is expected to have great consequences for the methods of future HIAs. The project QHIAS (Quantification of health impact of air pollution in Switzerland) has as overall goal to develop a methodological framework for HIAs that integrates recent novel insights from air pollution health research and is in alignment with international HIA initiatives.