Aren't those ultra lights supposed to have less tar? They used to be low tar, but then cigarette makers stopped being able to say low tar..
Her cigarettes were as low tar as mine were high, I bummed from her once, and that thing wasn't even a cigarette! In the world of cigarettes, I'd say hers were the exact opposite of mine.
Yep, that's why I always smoked ultra-lights! But, I got just as much smoke from mine...as my brother got from his full flavor red/white pack Winston's!
About your SIL being an ultra light smoker and still coughing her head off when quitting - You said you both had lots of lung related illnesses. Whether she smoked ultra lights or full flavored...her lungs were being made weaker each time she had 1 of those illnesses. So she may have been very energetic and very very very healthy otherwise, but her lungs weren't.
I know that when I was diagnosed with mild beginning stage of COPD years ago (mine was emphysema)...no one who knows me could believe it! I was the Energizer Bunny's twin, as far as energy! I never got tired doing anything (even strenuous stuff), never got out of breath, very very rarely was ever sick with anything (even colds), didn't have a smoker's cough, etc. They couldn't understand, and neither could I, how I could have mild COPD and it didn't physically affect me at all...outwardly.