If you read further down there are plenty of citations.
"Brian Fligor, an audiologist who has studied the impact of earbuds on hearing damage, says that people typically listen to their earbuds about 13 decibels higher than the background noise."
"2014 research, conducted by Fligor and others, looked at the impact of urban environments on people’s headphone listening levels by measuring sound levels through a mannequin’s ears. The research involved asking passersby to take their headphones off and place them on this mannequin at the same volume level they had been listening to. The average listening level was 94 decibels, 58 percent of people polled were exceeding their weekly sound exposure limit — and an overwhelming 92 percent of them were wearing AirPod-style earbuds."
"2014 research" links to https://www.researchgate.net/publication/261256174_Cultural_...
"According to the American Osteopathic Association, approximately one in five teens today suffer some form of hearing damage, a rate that’s 30 percent higher than it was 20 years ago. The World Health Organization estimates that over “1 billion young people” are at risk of hearing loss, primarily from listening to music on headphones or earbuds."
There are links in those two sentences, too.