The aim of this project is to discover - in a multidisciplinary approach - safe cleaning for school buildings that results in a reduction of harmful chemical, particle and microbial footprint. We will implement initial data collection and questionnaire survey followed by laboratory-, chamber and intervention field experiments in order to gain new information on the contribution of cleaning agents on occupants’ exposure in school buildings. Initial data collection and questionnaire survey will provide information on commonly used cleaning agents and establish how cleaning practices involving these chemicals relate to pupils’ absence from school. We will use human biology mimicking toxicity tests to predict potential harmful effects of cleaning agents in-vitro. Test chamber experiments will reveal the release of volatile organic compounds and particles into indoor air upon application of different types of cleaning agents and application methods under varying environmental conditions and using different surface materials. In these experiments, the response of the microbiota on the material surfaces will be investigated, relevant to human exposure as such and also contributing to the reactive interface for chemical and particle emission. Studies on the survival and the re-establishment of microbial communities on surfaces are complemented with measurement of adenosine triphosphate (ATP) to provide information about cleaning effectiveness. We will investigate dispersal of emissions following cleaning by analysing the flow field patterns and model the influence of varying air exchange rates on the flow field by using computational fluid dynamics (CFD). Simulations will evaluate different ventilation strategies as means to reduce cleaning associated exposure. A longitudinal field study with chemical, particle and microbial monitoring will reveal the impact of cleaning interventions on classroom exposures under real-life conditions. Based on the results of this project, we will produce a list of recommendations and best practices on cleaning processes and cleaning agents in school buildings, applicable also to other public buildings.