Summary The project Chemical Health Risks in Military Operations develops chemical risk assessment methodologies for emergency personnel including soldiers, firefighters, police, and coast guards with the aim to increase their knowledge and ability to assess risks in emergency situations and to support and improve their exercises. Results regarding hazardous aerosols and methods to assess aerosol exposure from a chemical, toxicological and physical perspective are presented. In addition, guidance is given on how the results can contribute to improved risk assessment methodology. A distinct problem formulation and a hazard identification based on generic characterization methods are the basis for evaluating complex aerosols. Unique scenarios place great demands on sampling strategy where small and remotely controlled samplers have shown great potential. To assess health effects of complex aerosols, for which guidance levels are often missing, dose-response relationships and toxic effects using in vitro systems based on human cells were studied. Well performed steps for hazard identification, exposure assessment and dose-response analysis, uncertainty factors and risks can be evaluated with the aim to identify safe levels in exposure situations. From a first responder perspective, this can result in more accurate identification of risk areas, safer action times in hot zones and better choice of personal protection level.