My dogwood trees have grown too tall and block the air on my deck as well as my view. Can they be cut back. If so how much and when?

Any woody branches must not be pruned until late fall to very early spring, at most 1/3 per year. Even a third is a lot. Prune the inner small softer branches and any suckers off the trunk any time except the hottest part of summer.
Little inner branches that rise up vertically off a horizontal branch are the first ones to eliminate, then any little ones that crisscross with each other.
I wouldn't attack the very top of the trees, because they aren't really what is blocking your breeze and view, are they? They will just looked chopped.

You can judiciously prune smaller inner branches and shoots anytime. Serious pruning should be done when dormant, after leaf fall. DO NOT prune the top off.