I think domination in itself is pretty hard on the body. It probably asked a lot of concentration and willpower. Take also into account this is the first time he uses domination completly intentional. The previous time it was mostly unintentional and merly proved the point that he also should be able to use domination. Minhoon is also sensitive to smells and I don't think he would be completly resistant to his own smell (and also is own command). The CEO asked to clear the air probably because to room was completly filled with Minhoon's sent (and command) by clearing the air he probably wanted to lift or weaken the strenght of the command because it was the end of the photoshoot.
Minhoon’s scent coupled with the CEO/father’s made the others lurch and cover their noses. Notice how the CEO/father walked in with a trail of red aura (domination)? He’s not affected by Minhoon’s scent like the rest and he knows how to control his compared to Minhoon who’s barely keeping it together. I’m fairly sure the father was sizing Minhoon up. Despite it being his first time using his scent as a ‘weapon’ of sorts, Minhoon did a good job compared to how he used to stagger under the father’s domination (however, Minhoon did waver a little if you see the little text effects near him). He even managed to keep it in until the end of the shoot.
Later we see our MC all red and affected on the bed later with Hyungwoo, while the father shrugged it off and went about his business.
I didn't understand completely what happened between the ceo and Minhoon, did both have "domination" going on? Because Minhoon seemed to have an hard time answering his question, or is "domination" heavy to show too? Otherwise I can't understand why Minhoon couldn't walk anymore at the end of the photoshoot, if not under the influence of "domination". The ceo said also to clear the air, so...