There are a number. There are 18 Canada motor vehicle safety standards that apply broadly to buses, whether they are motor coaches, transit buses or school buses. There are specific additional requirements that have contributed to the exceptionally strong safety record of school buses, making them the safest vehicles in Canada. Examples would be the requirements around compartmentalization that specifically protect school children in the event of rear-end and frontal collisions. There is also, for example, Canada Motor Vehicle Safety Standard 111, around mirrors and rear visibility systems for school buses. CMVSS 108 is around lighting and reflective devices. This helps control traffic that goes by school buses and requires school buses to have flashing lights. CMVSS 217 is around bus window retention.
On April 4th, 2019. See this statement in context.