I think that it may be, but I wonder if it is sometimes more than venial in certain circumstances.
Like, if a smoker insists on smoking next to someone’s oxygen tank in the ICU, like I actually saw years ago before we had laws, I wonder if it’s still venial, if the person knowingly does this, doesn’t care whether that person lives or dies.
I’ve had where my sister had Raynaud’s Disease, and my family would ask at a public event for her to refrain from smoking due to my sister’s health problem. She wouldn’t. When a person knows it could have even worse consequences, doesn’t care, continues to smoke inspite of pleads to stop, where one person could put another in the hospital, I wonder if those circumstances could change the sin into a mortal sin.
Well, sometimes smokers kill not only themselves but other people. When their second-hand smoke kills another person, and they refuse to stop, I can’t help but wonder if it’s then a mortal sin.