I don't use a nasal spray, I have one that is similar to the image below.
I am not that concerned about H2O2 droplets in th lung. I figure that because of the size, and the constant breathing and the sliding down motion, not much H2O2 is in one spot.
Besides, as I said I make mine at 2% strength and I feel it is still strong enough. Beside I feel that a lot of the spray is rather reaching the inside of the mouth and the back of the throat (which should be very good for those who have a cold or flu).
After I finished spraying, I wait a couple of secs and wash my mouth down of the h2o2 with water (distilled or clean, no tap water).