firmware attacks are not limited to high profile machines and significant targets. Read r/badBIOS subbreddit of reddit.com.
bwrighttwo, to answer your question, if your computer is infected with BadUSB or BadBIOS
, there does not appear to be a method of safely copying personal files to a replacement air gapped computer. For an updated definition of air gap, see /r/BadBIOS subreddit of reddit.com. A compromise may be to keep personal files on an infected 'air gapped' computer and have a second computer that has its microphone, conductive speakers and piezo electro transducer removed to connect to the internet that does not have older personal files on it.