Canadian Public Safety Personnel (e.g., correctional workers, dispatchers, firefighters, paramedics, and police) are regularly exposed to potentially traumatic events, some of which are highlighted as critical incidents warranting additional resources. Unfortunately, available Canadian public safety personnel data measuring associations between potentially traumatic events and mental health remains sparse. The current research quantifies estimates for diverse event exposures within and between several categories of public safety personnel. Participants were 4,441 public safety personnel (31.7% women) in 1 of 6 categories (i.e., dispatchers, correctional workers, firefighters, municipal/provincial police, paramedics, and Royal Canadian Mounted Police). Participants reported exposures to diverse events including sudden violent (93.8%) or accidental deaths (93.7%), serious transportation accidents (93.2%), and physical assaults (90.6%), often 11+ times per event. There were significant relationships between potentially traumatic event exposures and all mental disorders. Sudden violent death and severe human suffering appeared particularly related to mental disorder symptoms, and therein potentially defensible as critical incidents. The current results offer initial evidence that (a) potentially traumatic event exposures are diverse and frequent among diverse Canadian public safety personnel; (b) many different types of exposure can be associated with mental disorders; (c) event exposures are associated with diverse mental disorders, including but not limited to posttraumatic stress disorder, and mental disorder screens would be substantially reduced in the absence of exposures; and (d) population attributable fractions indicated a substantial reduction in positive mental disorder screens (i.e., between 29.0 and 79.5%) if all traumatic event exposures were eliminated among Canadian public safety personnel. (PsycINFO Database Record (c) 2019 APA, all rights reserved)