The National Highway Traffic Safety Administration (NHTSA) has expanded a recall of vehicles with potentially dangerous Takata airbags to 7.8 million.
The NHTSA warned that owners should take “immediate action”.
If deployed with force, the airbags have the potential to eject deadly shrapnel at passengers.
The NHTSA has identified 10 manufacturers who used Takata as a supplier, including General Motors, Honda, and Toyota.
The agency has told those who might own affected vehicles to check the list at www.safercar.gov, and specifically warned those living in more humid climates such as Florida and Hawaii to get their vehicles inspected.
“Responding to these recalls, whether old or new, is essential to personal safety and it will help aid our ongoing investigation into Takata airbags and what appears to be a problem related to extended exposure to consistently high humidity and temperatures,” said NHTSA deputy administrator David Friedman in a statement.
Initially, the NHTSA said that only 4.7 million cars could be affected, but it has increased the number of vehicles twice in recent days.
Japanese supplier Takata warned recently that older airbags could explode with too much force, which would send plastic and metal parts towards passengers with enough force to injure them.
Takata said it estimated that around 12 million vehicles around the globe may contain the parts.
The recall notices have been ongoing for the past 18 months, but regulators and car manufacturers have warned that only a small percentage of those cars potentially affected have been returned and inspected.
The majority of the affected vehicles – more than five million – are Honda cars manufactured between 2001 and 2011, including the Accord, Civic, and Pilot models.