Smoking zone area limit

I have an office building of six floors, I need to know If there's a limitation to the percent of smoking zones, in other words, can I make two floors out of the six floors as smoking zones? in that case, can I recirculate return air of each of these two floors? knowing that LEED recommendations states that: "At a minimum, the smoking room must be directly exhausted to the outdoors, away from air intakes and building entry paths, with no recirculation of ETS-containing air to nonsmoking areas.." so I might be able to recirculate ETS-containing air to smoking areas normally.