Roughly half of officers don't wear seatbelts even though traffic accidents are now the leading cause of police duty deaths, according to a study by a California police training board.

The finding comes in an upcoming study by the California Commission of Peace Officer Standards. At the same time, the LAPD has launched an awareness campaign after learning that 37% of the officers involved in crashes in 2012 weren't wearing seatbelts.

The LAPD is using the 25th anniversary of a 1988 crash that claimed the lives of three officers to highlight the importance of wearing a seatbelt on duty.

Officers often don't wear their seatbelts so they can have quick access to their sidearm in a possible ambush attack. A former police chief who studied the trend called it the myth of the "ninja assassin" in an interview with the Associated Press.