According to a new study by the University of North Carolina Highway Safety Research Center, funded by the AAA Foundation for Traffic Safety, an estimated 284,000 distracted car drivers are involved in serious crashes every year.

The study found that auto drivers were most often distracted by something outside their vehicle (29.4%) followed by adjusting a radio or CD player (11.4%). Other specific distractions included talking with other occupants (10.9%), adjusting vehicle or climate controls (2.8%), eating or drinking (1.7%), cell-phone use (1.5%) and smoking (0.9%).

“We found that 15% of drivers in the study were not paying attention and just over half of these (8.3%) were distracted by something inside or outside the vehicle,” said Dr. Jane Stutts, manager of epidemiological studies at the UNC center and author of the study.

The study revealed that drivers under 20 were likely to be distracted by tuning the radio or changing CDs, while young adults (ages 20 to 29) seemed to be more distracted by other passengers.

Drivers over 65 were more distracted by objects or events happening outside the vehicle. Most of the distracted drivers were male (63%), in part because as a group males drive more than females and are more likely to be involved in serious crashes.

UNC’s researchers used the National Highway Traffic Safety Administration’s Crashworthiness Data System (CDS) for its study.