Smoking is the single most damaging risk factor to our health.
We can see some of the damaging signs for ourselves when we look at the skin of a smoker. In fact, it is usually quite easy to spot a smoker, certainly one who has been smoking for some years.
Take a look at the images below of sets of twins, in which there is a smoker and a non-smoker.
Supplementary text to be added ref smoking and the skin.