Vaporizing cannabis would certainly be preferable to smoking: The temperature of combusted cannabis is much higher than vaporized cannabis. Additionally, vaporized cannabis does not release the lung-damaging and irritating byproducts of combustion. However, vaporizing cannabis would still irritate the airways, so I would recommend that you use edible or oil forms of cannabis.
Interestingly though, cannabis exerts a definitive bronchodilator effect on the small airways. Cannabis has even saved a few lives of people caught without their rescue inhaler during a severe asthma attack.
I hope this helps!