A U.S. Senate panel on Tuesday will ask automakers and regulators why tens of millions of vehicles with faulty Takata air bag inflators remain on the road years after deaths prompted the largest auto safety recall in history.

Nearly 30 million vehicles remain unrepaired in the recall impacting 19 automakers. At least 22 deaths and hundreds of injuries worldwide are linked to Takata inflators that can explode, unleashing metal shrapnel inside cars and trucks. The defect led Takata to file for bankruptcy protection in June.

The recall process "may play out for another 10 to 15 years," Sen. Jerry Moran, who heads the subcommittee holding the hearing, said in his written opening statement.