I don't know if any of you have had this from BMW but it refers to metal parts escaping from the airbags and they require owners to take their vehicles for checking or replacement of the bags, all well and good but what puzzles me is how they intend to test it short of setting it off which does not sound like the best idea.
BMW are pretty good with recalls and if you own a car in an affected production batch then the advisory has probably been sent, that said if you own a second hand car check any recall work has been done. It should have been done but if a prior owner didn't bother, it needs doing ASAP.
As BT has said, they're not tested, they're replaced (either in part or the whole assembly).
If the concern is with metal fragments it's unlikely to be related to the Takata recall. That, as far as I know, was related to deterioration of the explosive used to deploy the airbag.
Mine was booked in for its first service, 18,000 miles on 9 months. They said they would do the 2 updates/ recalls required. I remember them saying one was for the ECU but didn't get what the second one was. I opted for contact to be done by email but tend to just delete them as they are usual marketing. So might have missed any message.
The car was picked up and delivered back. This time I did open the email and it included a video of the mechanic doing part of the work and explaining what he was doing. He also showed me my front tyres that were down to 2mm and suggested I changed them soon.