Following Monday's the initial 4.7 million car and SUV recall for potentially dangerous Takata air bags, the U.S. National Highway Traffic Safety Administration (NHTSA) has expanded the number of affected vehicles to 7.8 million.

This marks the second time the estimated number of affected vehicles released by the NHTSA has changed in recent days. Per ABC News, the regulatory agency has also admitted that the list it released on Monday contained inaccuracies.

In its latest consumer advisory, the NHTSA urges owners of certain Toyota, Honda, Mazda, BMW, Nissan, Mitsubishi, Subaru, Chrysler, Ford and General Motors vehicles to act immediately on recall notices to replace defective Takata airbags and impressed urgency upon those in the following areas: Florida, Puerto Rico, limited areas near the Gulf of Mexico in Texas, Alabama, Mississippi, Georgia, and Louisiana, as well as Guam, Saipan, American Samoa, Virgin Islands and Hawaii.

The U.S. Auto safety agency has revealed that the air bags' inflator mechanisms can rupture causing metal shrapnel to fly out at passengers when the bags are deployed. There have been at least four deaths linked to the defective air bags manufactured by the Tokyo-based firm, noted AL.com.

According to NHTSA Deputy Administrator David Friedman, "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. However, we're leaving no stone unturned in our aggressive pursuit to track down the full geographic scope of this issue."

BBC wrote that Takata has also warned that "airbags could explode with too much force, which would send plastic and metal parts towards passengers with enough force to injure them." Additionally, the firm estimates 12 million vehicles worldwide may be carrying the defective part.

This is the second large-scale recall in 2014, the first being GM's recall of millions of vehicles for faulty ignition switches.

Congress is aware of the problem and per a committee spokeswoman via ABC News, the NHTSA has already been requested by House Energy and Commerce Committee staff members to provide a briefing on the Takata air bags. Moreover, there is also a plan to have a dialogue with automakers.

To know if your vehicle in affected by the recall, authorities are directing drivers to check this site where they can search using their vehicle identification number.