Go ahead, blow smoke in your blackjack dealer’s face. If you’re playing at the soon-to-open Aria at CityCenter, they will hardly notice. That’s because Aria’s blackjack tables will be equipped with an air curtain that shoots straight up from the table, dividing dealer and players. That’s the next-to-best thing Aria could do to protect dealers’ health, aside from not allowing smoking in the casino, said Cindy Ortega, senior vice president of energy and environmental services for MGM Mirage, an owner of CityCenter.