Non-smokers in the 1970s and 1980s, how the hell did you survive the second hand smoke?

I grew up in a small town, and when I was 17, I signed up for the volunteer fire department in town. Part of the in-processing was getting a chest x-ray so they knew how fucked your lungs were before any exposure related to the position. Nurse asked me how much I smoked and thought I was lying when I (truthfully) said I didn't. She said my lungs looked like I'd been smoking at least a pack a day for at least a year.

My mom and every step-dad smoked like chimneys, spent a lot of my childhood in bars when smoking indoors was still legal. I don't know if the nurse was exaggerating the results, and I don't have a copy of the x-ray from back then. I also picked up the habit myself around 20 in the military and smoked a pack to 2 a day until we found out my wife was pregnant with our first kid. We both quit cold turkey that day. I assume I'll have lung or skin cancer at some point between all that childhood exposure, the damage I did to myself smoking for a decade, the aircraft fumes, and burn pit exposure from the military...and we didn't worry about sunscreen like we should have in the 80s/90s either.