The National Park Service today immediately began requiring visitors to every National Park to wear a face mask, regardless of vaccination status or community transmission levels.

Cases of COVID-19 have surged across the country the last two weeks led by the delta variant, according to USA TODAY .

All visitors, employees and contractors must now wear a mask inside all National Park Service buildings and in “crowded outdoor spaces.”

“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,” NPS Deputy Director Shawn Benge said in a statement.

The mask mandate will be in place until further notice.

‘Outdoor spaces’ is defined when physical distancing cannot be maintained, such as narrow or busy trails and overlooks.

“Being vaccinated is the most effective way to protect yourself and your loved ones from the dangers of the coronavirus. Masking in addition to being vaccinated will help prevent the spread of new variants and protect those who are more at risk of severe disease,” Capt. Maria Said, an epidemiologist in the NPS Office of Public Health and a member of the U.S. Public Health Service Commissioned Corps, said in a statement.

“This simple act of kindness allows us to be safe while we continue to enjoy the benefits of our national parks.”