Clarence Ditlow, a longtime advocate for tougher safety and emission standards for vehicles, died on Nov. 10 at the age of 72.

Ditlow, both an attorney and an engineer, had served as executive director of the Center for Auto Safety since 1976. Ralph Nader and Consumers Union established the auto industry watchdog group in 1970.

Under Ditlow, the center played a major role in pushing for some of the largest safety recalls in U.S. history, including the Takata air bag recall. Ditlow also played a pivotal role in achieving one of the center’s earliest goals: making air bags standard in all vehicles.

Ditlow and other representatives of the Center for Auto Safety have testified more than 50 times before congressional committees regarding auto safety, warranties and service bulletins, air pollution, consumer protection, and fuel economy.

“Spanning four decades, his work forced the auto industry to make vast improvements in the safety, reliability and fuel efficiency of the vehicles on which Americans depend daily,” the Center for Auto Safety said in a released statement about Ditlow’s death.