1. There is no such thing as "safe". At! All! And this woman has been doing something very risky her entire life!
2. As to her place of work, the counter forces something like a 4-foot or greater separation, and the 2-foot tall barrier and no ventilation essentially isolate her from customers' exhalations. And she wears a mask and gloves ... her actual risk would probably be little different from a year ago.
If, at age 60, she is alone, it sounds like smoking might not be the only less than wise choice in her life (unless she's a widow).