Current approved safety standards for helmets

As per the EA General Regulations, Article 122.2: Dress and Salute, the following will apply: 

Except where Sport Rules allows otherwise, riders and drivers competing in an EA competition, must wear an approved helmet with the chin strap fastened at all times. The same is recommended when riding a horse at any time.

More information 

The onus is on the competitor to comply with the new requirements.