DENVER (AP) - Starting this ski season, resort owner Intrawest is requiring helmets for all youth in ski school and students of any age in freestyle terrain parks.

Age limits for "youth" will be determined by each resort.

Previously, parents could opt out of having their children wear helmets in certain programs at some resorts.

By the 2010-2011 season, on-duty employees will be required to wear helmets in terrain parks or if they are guides or teachers for programs where guests must wear helmets.

The rules affect Copper Mountain, Winter Park and Steamboat resorts in Colorado, Stratton Mountain in Vermont, Mountain Creek in New Jersey, Tremblant in Quebec, Panorama Mountain and Whistler Blackcomb in British Columbia, and Snowshoe Mountain in West Virginia.