In April and May of last year, several Japanese automakers, along with BMW, recalled a total of 3.6 million cars over the same defect. Then on June 11 of this year, Toyota expanded that recall by 2.3 million vehicles — many for the second time, though for a different air bag — because, Takata said, it kept inadequate records. The number of recalled cars could still rise as automakers discover more models fitted with defective air bags.

Those numbers reflect in part stepped-up scrutiny by regulators, particularly in the United States.

The recalls announced on Monday, which included cars made by Toyota, Honda, Nissan, Mazda, Ford, Chrysler and BMW — were responding to an investigation opened this month by the National Highway Traffic Safety Administration after it received three complaints of injuries caused by the air bag inflators’ rupturing.

A Honda spokesman said the company was aware of more than 30 injuries and two deaths in the United States related to all the Takata air bags.

For those who have been injured, the consequences have been devastating.

In 2010, Kristy Williams was stopped at a red light in Georgia when the air bags manufactured by Takata in her 2001 Honda Civic spontaneously deployed. She was hit by metal shards from the canister that housed the air bag’s propellant; the shards were sharp enough to penetrate the fabric of the air bag and puncture her neck and carotid artery.