Takata airbag recallSix deaths and over 100 injuries have been blamed on defective airbags made by Takata, a Japanese company that is one of the world’s largest suppliers. Takata denied for over a decade that its airbags were defective, but it has finally admitted the problem. The company has agreed to double the number of vehicles recalled in the United States to 34 million, making it the largest automotive recall in U.S. history. The recall affects about one in seven vehicles on American roads.

The National Highway Traffic Safety Administration (NHTSA) will not know exactly which models will be recalled until it coordinates with automakers. The total number of recalled vehicles could change as more tests are conducted. The recall will affect some models made by BMW, Chrysler, Daimler Trucks, Ford, General Motors, Honda, Mazda, Mitsubishi, Nissan, Subaru, and Toyota.

Customers filed complaints about Takata’s airbags as far back as 2000. The airbags can explode violently when they deploy and send shrapnel flying into the passenger compartment.

Takata had initially blamed problems with the airbags on manufacturing errors, but in new filings it admitted that there were problems with the airbags’ design and components. The company said that the propellant in the inflaters, the explosive material that generates gases that inflate the airbags, can degrade if it is exposed to humidity and changes in temperature over a period of time. Former Takata engineers said that they had expressed concerns about the material over a decade ago but their concerns were not heeded.

Takata has acknowledged that its testing found leaks in some inflaters that could allow moisture to seep in over time. A former consultant said he warned the company about leaks and offered to sell them a different leak testing method, but he said his concerns were unheeded. Takata said that industry-mandated testing would not have uncovered the leaks.

Takata has disputed a report by the New York Times that it found defects in its airbags in 2004 but did not report them to regulators. Honda recalled 4,000 cars in 2008 and an additional 510,000 six months later after a fatal accident.

NHTSA investigated Takata in 2009 but closed the inquiry six months later, citing insufficient evidence. The agency launched a second investigation in June 2014 and began to demand that car makers issue recalls in the United States late last year. NHTSA has become more assertive toward companies like Takata since Mark Rosekind took over as administrator.

Safety regulators began to fine Takata $14,000 per day in February for not cooperating fully in NHTSA’s investigation. Now that the recall has been expanded, the fine will be suspended. It is unclear whether the money will be collected.

It could take several years to complete repairs on all of the recalled vehicles. Rosekind said people should continue to drive their cars but should check with their dealers to see if their vehicles are affected and, if so, have them repaired as soon as possible.