Ski helmet standards EN 1077:2007:
https://www.satra.com/spotlight/article.php?id=429
-helmets should be of low weight, be easy to put on and take off, be usable with spectacles and not significantly impair hearing.
-minimum width of 15mm for the retention system straps and also that the strap shall not include a chin cup.
-each helmet is subjected to three pre-treatments: exposure to room temperature (20°C), low temperature (-25ºC) and artificial ageing. The duration of the room temperature and low temperature pre-treatments are a minimum of four hours
-Shock absorption testing is carried out on a drop rig utilizing instrumented head-forms. The impact velocity needs to be 5.42m/s
-acceleration of the headform during each impact must not exceed 250g
--impact surface is a flat steel anvil 130mm in diameter.
-impacted once at each of two points at least 100mm apart.
-A drop mass falls onto a conical punch positioned in contact with the surface of the helmet shell,
-Class A helmet (over ears), the required impact velocity is 3.84m/s (theoretically equivalent to a drop height of 750mm). However, for a Class B helmet, the required impact velocity is 2.71m/s (theoretically equivalent to a drop height of 375mm).
-the retention system will not stretch or slip significantly and can be unfastened after any incident.
-wearer’s view is not impeded: i) within an angle of 105° side to side, ii) upwards up to an angle of 25° and iii) downwards down to an angle of 45°.
The three big points--shock absorption for concussion prevention, penetration resistance (higher requirement for over-ears Class A), retention strap.