Exposure assessment is an essential tool in a product steward’s toolbox. This presentation will explore the when, how, and why of exposure assessments for product stewards during product development. The presenters will describe different tools and strategies to conduct exposure assessments at different stages of the product development process, including ideation, detailed design, and commercialization. In addition, this presentation will introduce chemical exposure modeling, an important strategy in the later stages of product development. The presenters will demonstrate the application of tiered exposure modeling through a practical case study that evaluates inhalation exposure from a consumer product. Deterministic and probabilistic functions of modeling tools will be used to demonstrate the data requirements and implementation of tiered modeling. Key concepts will include how to refine an exposure assessment modeling approach and what to do when you need data beyond the model defaults.