Dangerous Takata airbags in biggest-ever US recall

US safety regulators on Wednesday added another 35 million to 40 million Takata airbag inflators to the 28.8 million already in need of replacement, thereby more than doubling what was already the largest recall in US history.

These recall expansions are planned to take place in phases between May 2016 and December 2019, the US Department of Transportation's National Highway Traffic Safety Administration (NHTSA) said in a release.

The complicated recall impacts vehicles made by a dozen manufacturers including Honda Motor, Fiat Chrysler and Toyota.

"The most dangerous inflators are targeted first," Mark Rosekind, NHTSA's administrator, said during a news conference Wednesday. "We are absolutely not satisfied with current completion rates of recalls already under way."

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, the agency said.

The expansions mean that all Takata ammonium nitrate-based propellant driver and passenger frontal air bag inflators without a chemical drying agent, also known as a desiccant, will be recalled, NHTSA said.

A defect can cause air bags to explode and fire off shrapnel, with 10 known deaths in the United States and 11 worldwide. More than 100 people have been injured.

A 17-year-old girl from Texas is the latest victim of the malfunctioning air bag inflators. She was driving a 2002 Honda Civic in Fort Bend County when the car crashed and the air bag activated on 31 March, according to the NHTSA.

Two Democratic senators, Connecticut's Richard Blumenthal and Edward Markey of Massachusetts, said the expanded recall was not enough, and reiterated that all devices using ammonium nitrate should be replaced.

''Repeated stopgap partial steps like today's will only continue to put drivers, their passengers, and even others on the road at urgent risk," they said in a statement.

Moisture factor

Researchers contracted by a coalition of auto manufacturers in February determined moisture to be a major factor in the air bag ruptures that can shoot shrapnel at drivers and passengers in the front seats of the impacted cars. Cars with a certain Takata air bag design are prone to water seeping in, with vehicles operating in a humid environment deemed at most risk, they found.

In November, US auto safety regulators announced a fine of up to $200 million for the Japanese auto parts maker - $70 million for mishandling the way it recalled the millions of air bag inflators and an additional $130 million if its settlement with the NHTSA is violated.