What if you find out that smokers have high productivity?
Smokers tend to receive harsh treatment. They claim that smokers take a smoke break about once every hour even if the company doesn't approve. Considering that they take 10 min break every hour, this amounts to 60 extra minutes per day. Non-smokers will say "unacceptable!" (I am a non-smoker myself).
However, considering productivity, actually, smokers may sometimes have higher efficiency. That is, smokers are taking a 10 minute-break in an hour, so their minds are clear after the break. Reading any books on productivity will say taking about 10 minute-break in an hour will improve productivity. Taking breaks this frequent will cause less load on the back, so it may be good for postures as well.
Non-smokers who don't take any breaks besides lunch break will accumulate fatigue, leading to lower productivity instead.
Instructing smokers to actively take smoking breaks once every hour may lead to increased productivity in the company as a whole.