Originally Posted by stubborn_d0nkey
Because CC is gas and smoker has no haki
That could very well be the reason. At this point though I find it strange for Oda to not upgrade Smoker. He fought against Boa Hancock who was known for her Haki. She kept and subdued smoker long enough for Luffy to get ahead. I would of hoped that he would learn some Haki to boost his range and skill.