I smoked from when I was 14, heavily when I hit my 20s and then the p started.
I noted that after binge sessions at the pub where I drank a bit but smoked heavily, the p was very aggravated.
Then I had kids, so the pub sessions stopped but the p damage was already done, and it never really went away.
In these years I smoked 15 - 20 a day.
Then on new years eve 2003 we finally got a night off and went to a party where I drank and smoked heavily.
The next few days the p was horrific, covering most of my back, torso and upper limbs, and upper legs.
I quit smoking that year.
But I think its like a back injury; once its done its very easily triggered again.
Methotrexate finally almost cleared this but made me sick, so a few years of suffering sickness daily I am now switching to etanercept. The switch over period is proving hard work, the p is back so quick

my lowesr back and abdomen are a weeping mess right now... sorry Im off on a tangent.
I havent smoked since I quit in february 2004