Abstract Health impact assessments (HIA) provide decision-makers with sound information about the health implications of policies or programmes and projects. Using an economic lens to perform HIA and to study policies to be implemented, can be a daunting task as there are many challenges can hamper its performance. Data scarcity and difficult access to it, is frequently a challenge when analysing health policies, emphasizing the importance of methods for collecting primary data. Additionally, something even rarer is to have data stratified by socioeconomic variables. This is of particular importance as it is the way of evaluating the impact of policies on equity of the health systems. Information on both the costs and outcomes of the interventions are essential. However, the transferability of this information for other contexts or countries can be hampered by many specificities in the different sides of the equations, such as the heterogeneity of unit prices in different countries. Often relying on cost-benefit analysis, HIA exercise encompass with the two processes in terms of costing, i.e. assessing the input costs of a policy and monetizing the health outcomes or losses on outcomes. Effectiveness of a policy mainly concerns with long term impacts of health, but economic evaluation might fail to monetise the exact effects with pros and cons. In fact, with the enormous options on mathematical modeling providing a clear picture of the impact of health policies, might diverge the researchers or decision makers for a clear and straight pathway towards nvironmental and health governance. Specifically, to the environmental risk factors to health, these also lead to an extra layer or step as a linkage between exposure to the risk factor and the subsequent impact on health might be faced later. Interministerial work is thus essential in order to overcome specific problems on access and data quality. In this round table, different perspectives will be given on the challenges of performing an environmental HIA, with some practical examples. From data to knowledge translation, we will focus on specific use cases to describe mental health systems. This roundtable was supported by EUPHA Public Health Economics, EUPHA Health Impact Assessment and EUPHA Environment and Health sections, as well as supported by National Funds through FCT - Fundação para a Ciência e a Tecnologia,I.P., within CINTESIS, R&D Unit (reference UIDP/4255/2020). Key messages • Data availability and access are still among the main challenges to overcome when performing a health impact assessment. • A Health in All Policies approach, the best option for evaluating environmental policies, highlight the importance of interministerial work. Speakers/Panelists Marco Martuzzi Istituto Superiore di Sanità, Rome, Italy Brecht Devleesschauwer Sciensano, Brussels, Belgium Marija Jevtic University of Novi Sad, Faculty of Medicine, Novi Sad, Serbia Vlatka Matkovic Health & Environment Alliance, Brussels, Belgium