A logo of Takata Corp is seen with its display at a showroom for vehicles in Tokyo, Japan, May 8, 2015. Japan's Takata Corp said on Friday it expects to post a return to profit this fiscal year, emerging from a massive global recall crisis surrounding its exploding air bags. Reuters/Yuya Shino

Japanese airbag manufacturer Takata declared airbags in about 33.8mn US vehicles defective, US Transportation Secretary Anthony Foxx announced on 19 May. Ten automakers have already recalled nearly 17m vehicles, CBS News reported.

The company's airbags have been found to contain a propellant that explodes violent when activated, potentially causing grave injuries to drivers and their passengers. Foxx said the airbags have caused at least five deaths in the US and more than 100 injuries.

Takata has refused to acknowledge the defects in the air bags until now, Foxx told reporters during a press conference. According to the New York Times, the company at one point said the National Highway Traffic Safety Administration could not force it to declare a recall.

"That changes today. Today I announce that Takata has agreed to declare that the airbags deflators are defective," Foxx said.

Mark R Rosekind, the administrator of the safety agency, said: "From the very beginning, our goal has been simple: a safe airbag in every vehicle. The steps we're taking today represent significant progress toward that goal."

"This is a monumental effort, there is no doubt about it," Foxx said. "It's fair to say this is probably the most complex consumer safety recall in U.S. History. So we have a lot of work to do." He added, "Lives are at stake. It's our job to protect them."

Additional testing needed to determine final recall number

While a final count of all the makes and models included in the recall has not been reached, Rosalind told the Times that the number of defective vehicles could go down as additional tests are made. According to the Times, vehicle repairs could take years to complete.

"It's fair to say this is probably the most complex consumer safety recall in U.S. History. So we have a lot of work to do. Lives are at stake. It's our job to protect them
- US Transportation Secretary Anthony Foxx

The 10 car makers that have already begun to recall vehicles are: BMW, Fiat, Chrysler, Ford, General Motors, Honda, Mazda, Mitsubishi, Nissan, Subaru and Toyota. According to CBS News, the expanded recall would basically double the number of vehicles and add on another car maker, Daimler Trucks.

According to the Times, former Takata engineers told the newspaper that they had raised concerns about the explosive material used in the airbags over a decade ago. However, those concerns were ignored. The company's patents also reveal how its engineers struggled to stablise the explosive material, ammonium nitrate, in the airbag propellant.

Takata also acknowledged the airbag inflaters had leaking problems, the Times reported.

The company had been fined $14,000 (£9,000) a day by US federal safety regulators for not cooperating with the investigation. However, the agency later suspended the fine, which had surpassed $1m, with the recall expansion.