Japanese automaker Mazda Motor Co. said Friday it is recalling nearly 540,000 cars and pickups in North America for air bag inflators that can explode, adding to the massive recall of vehicles with potentially defective Takata Corp. air bags, reports The Detroit News.

Recalled cars include the 2003-08 Mazda 6, 2006-07 MazdaSpeed 6 and the 2004-08 RX-8 for defective driver’s-side bags. Mazda’s recall also includes the 2004-06 B-Series pickups for defective passenger-side bags.

The latest recall includes 330,000 vehicles that Mazda said last year it would repair under a safety improvement campaign, that the National Highway Traffic Safety Administration classified as a recall.

In total, 11 automakers are recalling nearly 34 million vehicles after Takata last month declared the vehicles defective. The decision effectively doubled the recall of vehicles with Takata vehicles that had already been called back. Worldwide, more than 50 million vehicles have been recalled for air bag inflators that can explode and fling metal shrapnel at drivers and passengers when the bags are activated.

The safety defect is linked to six deaths and 100 injuries, with all of the deaths reported in Hondas.

To date, eight of the 11 automakers have notified NHTSA about which new cars are part of the latest recalls. Just over 30.4 million vehicles have been named to the recall to date.

Takata may have to again replace the air bags of at least one-tenth of the 4 million vehicles that already have been repaired. But the company hasn’t identified which cars and trucks are covered by the need for a second repair.

NHTSA Administrator Mark Rosekind told The Detroit News on Thursday the agency plans to announce when all the automakers have submitted notifications. He told Congress this week it could still take a couple weeks before all vehicle identification numbers are on safercar.gov.

Takata came under criticism this week for saying it will continue to use ammonium nitrate in replacement air bags, even as it admits the propellant is a factor in the explosions. Although the exact cause of the problem is unknown, it is believed that high heat and humidity can cause the propellant to become unstable and ignite with more force than intended.

The company’s rivals don’t use that propellant, and Takata has said it will transition away from it. Rosekind said that decision is up to Takata. “We’re just pointing out there’s all these other solutions that work just fine,” he said.

Rosekind praised Takata for its cooperation after it signed a consent order with NHTSA on May 19. “There’s a dramatic difference,” he said. “We went 180 degrees from denial to not just acceptance… but now we have a path forward.”

It could take Takata two years to build enough replacement parts, but Rosekind hopes that process can be sped up. NHTSA is moving into “the driver’s seat” by using its authority under a 2000 law to oversee the massive recall, and Rosekind said he hopes in that position the agency can speed replacement parts to market. NHTSA will hold meetings with automakers and Takata.