Bar owners would have to prove catastrophic losses over consecutive months to obtain an exemption from the District’s impending smoking ban, according to a draft resolution circulating through city hall.

The complete proposal, obtained by The Examiner, but not yet submitted to the D.C. Council, also set rules for enforcement, language for warning signs and fines. The smoking ban takes effect Jan. 1 for all indoor workplaces, including bars, taverns and nightclubs — though the dining areas of restaurants are already under the prohibition.