The study is being overseen by Jeff Taylor, the manager of the Epidemiology and Disease Surveillance Unit with Austin Public Health. He’s joined by three epidemiologists from the CDC who will focus on severe injuries that occurred to e-scooter riders in Austin. The study has already completed the data collection process and is now being summarized for a final report.

Preliminary observations from the study found that the vast majority of injuries — 98 percent of them — happen to riders who aren’t wearing helmets. Nearly half of all riders involved in accidents had a blood-alcohol level above the legal limit and 52 percent tested positive for use of an illicit substance. Taylor noted that while many people believe accidents occur at night, they happen at all hours of the day. They also rarely involve another vehicle.

Electric scooter injuries have been the subject of a number of recent studies, including a Consumer Reports investigation that found there were at least 1,500 people treated for scooter-involved injuries in the US over the last year. Still, companies like Lime and Bird have rapidly expanded their presence in major cities in the US, Canada and the UK. Engadget reached out to Lime and Bird to find out if either company is cooperating with the study. We will update this story if we hear back.