As of last week, it's mask season again in U.S. National Parks, where restrictions had been eased a few months ago. In light of the current rise in delta infections, masks are back for all indoor spaces and crowded outdoor spaces.
The National Park Service directive applies to visitors, employees and contractors, and follows guidance from Centers for Disease Control. It will remain in effect until further notice, and defines 'crowded' outdoor spaces as places where physical distance can't be maintained, such as narrow or busy trails and overlooks.
National Park Service Deputy Director Shawn Benge explained that the measures are necessary because “Visitors to national parks are coming from locations across the country, if not across the world. Because of this, and recognizing that the majority of the United States is currently in substantial or high-transmission categories, we are implementing a service-wide mask requirement to ensure our staff and visitors’ safety.”