Yes, it is.
I had to use prescription fentanyl for 6-8 months a few years back. It's a small patch you stick on like a piece of tape.
Personal slide: God is very good, there was an innovative surgery to alleviate my issue. I had been super upset about using the fentanyl, just the addiction stories scared me. It pushed my husband and I to look into some of the newer, advancements in surgical techniques. I believe God guided us to the correct surgeon and "new thing." I was very concerned about withdrawal stuff. I never had any issues with that. Again, I'm giving God the glory for that, but it just didn't affect me.
So an aerial fentanyl attack would be a scary thing that masks alone would not protect us from.