Canadian dressage rider Jessica Rhinelander.
The same rule applies to riders of any age while riding non-competing horses.
Competitors failing to adhere to the rule will be eliminated and non-competing riders will be instructed to dismount.
After performing a test, the steward may ask the rider to dismount so that their helmet can be inspected. "The Board and the Rules Committee are aware that although the rule will be well accepted by many, there will be those who feel it is an unwelcome imposition," Dressage Canada said.
"Most of the feedback received in the last year on the subject of helmet safety was in favour of requiring approved helmets."
Given that the rule related to athlete safety, the board felt it was important to put the change in place as soon as possible.