Supposedly it was applied to him by a rag and not sprayed in the air. He'd be the only one affected, though some reports say one of the suspects arrested in the murder is suffering from some effects of VX.
It is possible that each woman has different chemical in her hands. The first one applies chemical to Kim's face, followed by the second one with a different chemical. Once two chemicals are applied on his face, they turn into VX. The second one could be affected since two chemicals started to react as soon as she applied her chemical. She might have gotten some trace of VX before she released her hand from his face.
I am not sure if this is indeed the way it happened. But if it did, we have the first known case of "binary assassins."