Could smoking marijuana for over a year cause lung disease?

Sure, While it depends on quantity, the normal toxins in pot smoke (assuming it has not been sprayed with even more toxic subtances) hae been considered equivalent to a pack of cigarettes. Think about it...Tokers suck it in and hold it down in their lungs, right!? Chronic coughs from the smoke and some depressed immune function and chronic obstructive pulmonary disease, or worse are risks -.
You bet cha. Marijuana smoke contains bronchial irritants. Inhalation with marijuana is more prolonged & deeper than with tobacco. Higher combustion temperatures are reached as it is smoked to a shorter butt. This leads to a carboxyhemoglobin concentration that is5 times higher than tobacco. 3 times more tar is inhaled. Prolonged use of cannabis can lead to airway inflammation, wheezing & increased sputum.