Add smoking weed to a cause of COPD. Along with vaping now per the posted study. The following is about Willie Nelson, again. And many states want to legalize recreational marijuana? Really?
"(Nelson) underwent cellular therapy to improve his lungs before going on tour." "“Over the years I’ve smoked a lot of cigarettes, and I’ve had emphysema and pneumonia four or five times, so my lungs were really screwed up"
https://lunginstitute.com/blog/willie-nelson-and-cellular-therapy/
Excerpt: Though studies are finding marijuana to be less harmful than cigarette smoking, prolonged exposure can increase the risk of developing lung disease. "There’s been a lot of talk about marijuana being harmless, but I think it’s a lot more dangerous to the lungs than most dope smokers realize,” said Nelson in his autobiography, with Bud Shrake. “Especially the strong marijuana that’s around these days. Each year it seems to get a little stronger. The wise course is to not abuse it. Your lungs are not really supposed to breathe anything but oxygen—pure, fresh air. "
That's right, Willie.