tobacco is a known respiratory inhibitor it closes passages in the lungs the opposite of cannabis. though in the end inhaling any smoke is a negative. i now vaporize and have no cough anymore. my performance in racing has not improved but like i said i no longer cough in the mornings or the first 20 miles or so and my lungs feel clean and clear. i suggest everyone who cares about there health to invest in a good vaporizer particularly those with compromised immune systems.