Japanese airbag manufacturer Takata’s woes just got worse, much worse, as at the US Transportation Department’s insistence, they nearly doubled the amount of recalled cars, from 18 million to 33.8 million.

As reported by the Detroit News, this will make it the largest U.S. recall of any consumer product, “surpassing the callback of 31 million bottles of Tylenol in 1982 following a poison scare”.

The National Highway Traffic Safety Administration (NHTSA) said Takata agreed to a nation-wide recall of certain types of driver and passenger side air bag inflators made with a propellant that can degrade over time and which has led to ruptures that have been blamed for six deaths worldwide and more than 100 injuries.

The new actions expand the Takata passenger-side inflator recall that was previously limited to areas of high absolute humidity as well as the current nationwide recall of driver-side inflators to more than 17 million vehicles.

“Today is a major step forward for public safety,” U.S. Transportation Secretary Anthony Foxx said. “The Department of Transportation is taking the proactive steps necessary to ensure that defective inflators are replaced with safe ones as quickly as possible, and that the highest risks are addressed first. We will not stop our work until every air bag is replaced.”

These potentially defective airbags have affected many brands, including cars from the BMW Group, Fiat-Chrysler, Ford, General Motors, Honda, Mitsubishi, Nissan, Subaru and Toyota.

The government agency said it hasn’t determined precisely what’s causing Takata’s inflators to explode.

“Testing and investigation by Takata, auto manufacturers, and independent researchers have not yet established a definitive root cause of the inflator malfunctions. NHTSA’s analysis of test results and engineering reports from independent organizations points to moisture infiltrating the defective inflators over extended periods of time as a factor,” said NHTSA in a statement.

“Over time, that moisture causes changes in the structure of the chemical propellant that ignites when an air bag deploys. The degraded propellant ignites too quickly, producing excess pressure that causes the inflator to rupture and sends metal shards into the passenger cabin that can lead to serious injury or death.”

The NHTSA hasn’t issued a complete list of all the cars affected by the massive recall yet, but it has established a new website at www.SaferCar.gov/RecallsSpotlight, where it will post new information.

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