The airbag investigation now includes side air bags which use a different Takata inflator than the targets of the original probe. The inflator, known as an SSI-20, has been recalled by General Motors Co. on certain 2015 models. Volkswagen AG has also reported a SSI-20 rupture.

Depending on what investigators find, the Takata recalls could be expanded, NHTSA said. It’s concerned about how additional recalls could affect those already under way. Any expansion would be done in a way to ensure the highest-risk cars are fixed first

Legal authority

The agency is also considering whether to use its legal authority to compel manufacturers to speed up recall-related repairs, or get parts to vehicles at most risk more quickly. It’s monitoring the supply of replacement parts and could order companies to step up production. It could also, for the first time, order automakers to set up additional authorized repair facilities if it determines there aren’t enough technicians at existing dealerships to meet consumer demand.

NHTSA said it’s also considering appointing independent monitors who will oversee automakers’ air bag repairs, communicating directly with the companies an a day-to-day basis.

Regarding the black market for air bags, law enforcement agencies in Miami have described underground networks stealing inflators -- including defective Takata-made versions -- and putting them up for sale, NHTSA Administrator Mark Rosekind told reporters.

“We’re learning about these groups all over the country, basically ripping off inflators, because they know there’s a need for them right now,” Rosekind said.

It’s more about air bag inflators and modules being valuable auto parts than consumers desperately searching for ways to replace their Takata air bags, Timian said.

Humidity and age

In their update of the safety investigation, NHTSA officials said they haven’t been able to determine a root cause for the Takata defect, which can cause air bag inflators to explode, sending shrapnel toward drivers and passengers. The agency is more convinced than ever, though, that the defect is triggered by prolonged, constant exposure to high humidity and age.

A 10-year-old vehicle in hot, humid Florida will be more at risk than a 3-year-old vehicle anywhere, or 10-year-old vehicle in a northern state like New York or Ohio, said Stephen Ridella, NHTSA’s director of vehicle crash-worthiness research.

Parts production has increased to 2.8 million replacement kits in the most recent month, NHTSA said. The agency has enlisted three other parts suppliers, Autoliv Inc., Daicel Corp. and ZF TRW Automotive Holdings Corp., to produce inflators for Takata-assembled repair modules, the agency said.

No final decision has been made on ordering automakers and Takata to step up production and speed repairs, Rosekind said. The agency will make a determination by Thanksgiving, he said.

Still, the recall completion rate is lagging. As of Oct. 9, just 22.5 percent of the affected cars in the U.S. had been repaired. In high-humidity states getting priority for repairs, like Florida and others on the Gulf Coast, the completion rate is 29.5 percent.

“If your vehicle is under a recall, please call your local dealer to arrange for free repairs,” Rosekind said.

Copyright 2018 Bloomberg. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.