I've seen blokes that can go hard all day long and there smokers now i'm not saying I'm for climbers smoking,but as an Ex smoker I'm not sitting on the fence..it is definitely a drug of addiction,it took me about 5 or 6 attempts to give up and to this day when a new pouch of tabacco is opened around me I still feel like taking a great big bite out of it,yes I think if you rule out smokers you mite miss out on a good worker as long as they lite up away from you and when their part of the job has a break in it,but it does come down to personal preference,theory is if they don't smoke their more productive because they don't stop for a cigy break,but hey its your body your lungs and if you want to smoke go rite ahead...please blow your smoke away from me...me a choice between a non smoker and a smoker..well I'll have to go with the non smoker