People need to understand what most helmets are designed for. They are not designed to reduce concussions. Their design is to reduce skull fractures. Most sports (other than football and ski/snowboard competition) helmets are designed with a sacrificial destruction principle. The helmet gets destroyed absorbing some of the impact.

They may be a minor amount of help with concussions but should not be used so as to allow greater risk taking. Some research suggests that helmets can cause a false sense of security thus increasing the risk taking negating the added value of the helmet.

If a skier were to run into a tree, the helmet will be of little value.