I smoke about two packs a month. How does the damage I’m doing to myself compare to someone who smokes daily?
That’s 40 fags per 30 days, so you ARE smoking daily. And given that smokers notoriously understate their consumption (cough cough) I’d suspect you are already literally smoking more than one daily.
But to answer your core question, if you’re smoking half as much as someone else you are doing yourself half as much damage as he is doing himself. Or, to put it another way, each and every cigarette does X amount of damage; you’re not getting any kind of low-quantity discount.
Literally? I don’t see why he couldn’t be smoking these 40 smokes over two or three nights at the bar. And I also suspect that this pattern would affect the health consequences… which is really what was asked in the first place.
What makes you sure that cigarette “damage” vs. # smoked is linear?
This sort of question has been asked many times before.
In short, once you go beyond gross lifetime consumption of 10-12 pack years, excess mortality starts to show up. Note that I’m not talking about excess risk of cancers or other ailments, only excess risk of death. Also, if you already suffer from below average health, all bets are off.