Put your brother in a headlock, pop a straw in his mouth (regular straw for drinking), and plug his nose with your fingers. Make him breathe in and out (through the straw only) until he has an anxiety attack.
You've just momentarily recreated emphysema. It sounds easy but try breathing in and out through a straw -- you can't breathe all the way out which is comparable to having emphysema.
Maybe try handcuffing him to an oxygen tank? Persistently ridicule him for being a moron?
I held my dad's hand while he died from this . . . and he quit smoking about fifteen years before that - it still got him in the end
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