From what I've read, plywood does not off-gas as much as particle board, due to having solid wood layers. But if you're noticing off-gassing, Safe Seal will help; it encapsulates the plywood, keeping the VOCs in. You may want to cover the board ends as well.
My personal experience was with 4 year old flakeboard subfloor. I pulled up the carpet and padding and the glue smell was stronger that I liked. The smell was gone after spraying with one thick coat of Safe Seal. For application, I used a $6 home/garden sprayer from the hardware store.
Amazon's product reviews are worth checking out.