Relenting under pressure from federal regulators, Honda has upgraded a "safety campaign" to add nine models equipped with faulty Takata air bags to the recall list.

The latest announcement affects certain 2003-'05 Honda Accord, 2001-'05 Honda Civic, 2002-'05 Honda CR-V, 2003-'04 Honda Element, 2002-'04 Honda Odyssey, 2003-'05 Honda Pilot, 2006 Honda Ridgeline, 2003-'05 Acura MDX and 2005 Acura RL vehicles, according to Edmunds.com.

The automaker hasn't specified how many vehicles are included in the recall, which was announced late Thursday night. Honda is not aware of any injuries or fatalities related to the recall.

Honda dealerships will replace the passenger front air bag inflator, a problematic part that has been related to at least four deaths in the U.S., according to safety advocates. Japanese supplier Takata reportedly didn't store materials for the air bags properly, resulting in air bags that can explode and rain shrapnel on the vehicle's passengers during a crash.

Weather seems to exacerbate the problem as well, and automakers have been conducting regional recalls for cars in high-humidity areas that are equipped with Takata air bags.

"The affected vehicles were originally sold or registered in 13 U.S. states and territories that consistently experience high absolute humidity," Honda said in a statement quoted by Edmunds.

Since 2008, Honda has recalled almost 7.6 million vehicles in the U.S. due to faulty Takata air bags.

The states and territories affected by the recall upgrade include Alabama, Florida, Georgia, Hawaii, Louisiana, Mississippi, South Carolina, Texas, Puerto Rico, U.S. Virgin Islands, Saipan, Guam and American Samoa.

According to a recent New York Times report, Honda was first aware that the air bags could explode a decade ago when a Honda Civic owner reported the problem. The automaker and Takata both wrote off the incident as "an anomaly."

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