I tend to go with the wino approach. I look around first, wipe it on my shirt sleave, then shove it right in my mouth. But don't go by me...I may die soon.
You might want to try a product called "Sterisol" which is a Germicide pump spray. It's supposed to clean, deodorize, and disinfect. It's used for woodwinds - mouthpieces and reeds. It's got a reddish pink color. You ought to be able to buy a bottle at a local music store. The main concern is to avoid using anything that will rust, corrode or damage your reeds inside the harmonica. I would buy a new one if you can see the orange rust on the inside of the plates. I'd hate to suck that stuff in too! Yuck! When I use this product, I let it sit for less than a minute and tap it out as much as I can. Best thing to do - is to keep asking around. You might find a better answer out there. Who knows? Good luck with picking up the harmonica again and finding consistant practice time!
I haven't picked up my harp in quite a long time but am going to start playing/learning again. I'm sure there are probably some pretty funky things growing inside that I don't want to inhale. Is there a solution that I can soak the harps in before I start using them again to kill all the old germs? The harps I have are Special 20's if that makes any difference.