DETROIT — Out of concern for the safety of drivers, the U.S. government may step in to manage a giant recall of air bags made by Takata Corp.

On Thursday, the government’s National Highway Traffic Safety Administration started the process to take control of the recall of 33.8 million air bags that can spew shrapnel into drivers or passengers.

The recall covers roughly one in seven vehicles on U.S. roads.

Many questions about the problem remain unanswered as an investigation continues, but here’s what you need to know about the largest automotive recall in U.S. history:

The danger

In a crash, the air bag can deploy with too much force and pelt unsuspecting drivers or passengers with fragments from a metal inflator, causing injury or even death. Six people have died and at least 105 have been injured.

The solution

Takata agreed this week to declare millions of air bag inflators defective. That added 17 million cars and trucks to existing recalls by 11 manufacturers — BMW, Fiat Chrysler, Ford, General Motors, Daimler Trucks, Honda, Mitsubishi, Mazda, Nissan, Subaru and Toyota.

Takata will need 33.8 million inflators for the repairs — so far it has made 3.8 million. At its estimated rate of production, it will take 2 ½ years to crank out enough to fix all the vehicles.

Is your car involved

If your car has the faulty air bags, the manufacturer will mail you a recall notice. But many won’t get notices until parts are available.

In the meantime, you can go to the NHTSA website, https://vinrcl.safercar.gov/vin/ and key in your vehicle identification number to see if you’re part of the recall. The number is stamped on the driver’s side dashboard near the base of the windshield, or it can be found on state registration cards. This isn’t fool-proof, though. It will take days or even weeks for Takata and automakers to determine which vehicles are covered and enter them into the database.

Should drivers worry?

Takata says inflator ruptures are rare, happening in only 0.51 percent of the parts it has tested and only in areas with high humidity.

But you might not find that reassuring. Check your dealer often to see if parts have arrived so you get on a priority list.

Recall speed?

If the Transportation Secretary, who oversees NHTSA, determines that the recalls are moving too slowly, the government can take over a recall. It can manage production, distribution and installation of replacement parts, including lining up other manufacturers to make more inflators.

The government would send inflators to high-humidity areas along the Gulf Coast first because the risk is highest there. Older cars would get priority as well, because the longer an inflator is exposed to high humidity, the greater the likelihood of failure.

Replacement inflators

Some drivers who already had the inflators replaced may have to do so again. Some automakers have replaced inflators with new ones that now have been declared defective by Takata.

But NHTSA says people should still get their cars fixed because a new inflator — even if it’s defective — is better than an old one. The chemical Takata uses to inflate the air bags, ammonium nitrate, becomes unstable over a long time period.

New cars

This is another tricky spot. NHTSA says there haven’t been any problems with inflators in cars newer than the 2011 model year, so those aren’t being recalled. The rest of the recalled cars date to the early 2000s.

Takata still uses ammonium nitrate in newer inflators, and the company says they are safe and effective “when properly engineered and manufactured.” But models keep being added to the recall, and investigators are looking at the safety of all Takata inflators. So it’s probably wise to ask your dealer if your car’s air bags are made by Takata and check periodically to see if it’s part of any recall expansions.