Some 1.1 billion young people are listening to music at volumes that endanger their hearing and can have other negative effects, the World Health Organization (WHO) warned Friday.

Nearly half of teenagers and young adults are exposed to unsafe sound levels on headphones, while some 40 percent put their hearing at risk at clubs, bars and sports events where "recreational noise" is excessive, WHO said.

The U.N. health agency called on youths to listen to loud music on their headphones less than one hour per day.

Nightclubs typically play music at 100 decibels, which is the equivalent of hearing a jackhammer at short distance, and is safe for only 15 minutes.

Entertainment venues should limit sound levels and offer protective earplugs and quiet zones to their customers, WHO recommended.

Hearing loss can have serious consequences for physical and mental health as well as for young people's prospects in education and employment, WHO warned.

"They should be aware that once you lose your hearing, it won't come back," senior WHO official Etienne Krug said.