(May 5, 2016) WASHINGTON – U.S. auto safety regulators ordered a vast expansion of the Takata airbag inflator recalls on Wednesday, more than doubling the number of hazardous parts covered by the callbacks in a move that the auto industry will spend the next several years sorting out.

The decision by the United States Department of Transportation’s National Highway Traffic Safety Administration follows the agency’s confirmation of the root cause behind the inflators’ propensity to rupture. Ruptures of the Takata inflators have been tied to 10 deaths and more than 100 injuries in the United States.

An additional 35 million to 40 million Takata-made inflators must now be replaced, on top of the nearly 29 million inflators already covered by the largest and most complex recall campaign in U.S. history.

The expansion covers all Takata inflators using an ammonium nitrate propellant that lacks a chemical additive to prevent moisture absorption, known as a desiccant.

“Today’s action is a significant step in the U.S. Department of Transportation’s aggressive oversight of Takata on behalf of drivers and passengers across America,” said Transportation Secretary Anthony Foxx. “The acceleration of this recall is based on scientific evidence and will protect all Americans from air bag inflators that may become unsafe.”

The five recall phases are based on prioritization of risk, determined by the age of the inflators and exposure to high humidity and fluctuating high temperatures that accelerate the degradation of the chemical propellant.

“NHTSA’s aggressive actions in 2015 means this recall is already a year ahead of where it would have been if the agency had waited for this research,” said NHTSA Administrator Mark Rosekind. “As a result, all of the most dangerous inflators responsible for the deaths and injuries are already under recall.”

NHTSA and its independent expert reviewed the findings of three independent investigations into the Takata air bag ruptures and confirmed the findings on the root cause of inflator ruptures. A combination of time, environmental moisture and fluctuating high temperatures contribute to the degradation of the ammonium nitrate propellant in the inflators. Such degradation can cause the propellant to burn too quickly, rupturing the inflator module and sending shrapnel through the air bag and into the vehicle occupants.

“The science clearly shows that these inflators become unsafe over time, faster when exposed to humidity and variations of temperature,” Rosekind added. “This recall schedule ensures the inflators will be recalled and replaced before they become dangerous, giving vehicle owners sufficient time to have them replaced before they pose a danger to vehicle occupants. NHTSA will continue to evaluate all available research and will act quickly to protect safety.”

NHTSA will also consult with affected vehicle manufacturers before revising the Coordinated Remedy Order that governs the accelerated program to obtain and install replacement inflators.

The Coordinated Remedy Program will continue to ensure that replacement inflators will be made available to highest-risk vehicles first. The revised Coordinated Remedy Program, to be announced this summer, will detail the updated vehicle prioritization schedule and the schedule by which manufacturers are required to procure sufficient supply of replacement parts to conduct the required recall repairs.