she is- or was- a chain smoker. I’m surprised she has made it to 91.
Perhaps the "Trust The Science" people have been lying to us?
It depends on when you quit smoking. Years ago I heard the theory that for every year you smoke, it a takes one full year for your lungs to recover.
I started smoking at 18 and quit at 39, which is 21 years of 2 packs of Winstons per day. In theory, my lungs should have recovered at age 60. My blood oxygen level today at 75 ranges from 96 to 99% and I have no lung issues.
My brother quit smoking in his 60’s. At age 75 his blood oxygen level was 86% and he was on oxygen all day long and could hardly breath.
So yes, if BB quit early, she recovered for a long life.
Smoking and excessive boozing is the worst thing you can do to your body.