Distractions can compromise a driver's mental skills. One study on the subject of mobile phones and driving safety concluded that, after controlling for driving difficulty and time on task, drivers talking on a phone exhibited greater impairment than drivers who were suffering from alcohol intoxication. In the US "During daylight hours, approximately 481,000 drivers are using cell phones while driving according to the publication on the National Highway Traffic Safety Association. Another survey indicated that music could adversely affect a driver's concentration."