Do mobs spawn in the air?

I'm about to bring my house to perfection by bringing the light-level at minimum 8.

However. In some areas of my house, when I jump, I see that there is a light level of 7. Can a mob spawn there or won't they spawn "in the air"? Means: Is a light level of 8 everywhere where you can stand enough to get rid of spawning mobs?

Solution 1:

Depends on what you mean by "spawn". (Your answer is "Yes" and "No".)

If a monster is spawned from a Monster Spawner, then:
Yes it can, as Monster Spawners will always create a mob near the spawner at intervals when the conditions around the Spawner are correct even if there is no available block to spawn on, as light is calculated in 3D space.

However, if the monster is spawned naturally then:
No, it does not. Monsters only spawn naturally on solid, non-transparent blocks at light level 7 or below. The light level at other points above or to the side of the solid block are not taken into account.