The Guidelines on Working with Nanomaterials provide a simple approach to assessing and controlling the risk around the use of nanomaterials even when the exact hazard presented by the materials is unknown. The unknown degree of hazard presented by nanomaterials is the most common state of knowledge for these relatively novel materials. However they tend to generally be more hazardous than the same material with a larger particle size. The guidelines provide for a way to categorize the hazard presented by different types of nanomaterials based on the form in which they are used and how they are used. There are also references to more sophisticated control banding approaches for those who wish to explore the potential toxicity of the materials in greater depth. The guidelines outline training, engineering controls required for various example activities, the PPE that would be additionally required and other ways to control exposure such as spill control, disposal and general housekeeping. The guidelines also include a template for a documented risk assessment for activities involving nanomaterials. If you use or will use nanomaterials in the lab please use this guideline as a starting point for control measures.  If you have any questions or concerns about nanomaterials you use or will use in the lab please feel free to talk to your HSO or contact ehs.office@utoronto.ca for more information.