Smokers must be greater than 20 feet from a public building’s entrances or operable windows while in the act of smoking. This is governed by California Government Code, 7597. This doesn’t apply to portions of the building that don’t have operable windows, doors, or the like. You should also consider posting signs near any HVAC air intake vents.
7597. (a) No public employee or member of the public shall smoke any tobacco product inside a public building, or in an outdoor area within 20 feet of a main exit, entrance, or operable window of a public building, or in a passenger vehicle, as defined by Section 465 of the Vehicle Code, owned by the state.
(b) This section shall not preempt the authority of any county,
city, city and county, California Community College campus, campus of the California State University, or campus of the University of California to adopt and enforce additional smoking and tobacco control ordinances, regulations, or policies that are more restrictive than the applicable standards required by this chapter.
7598. Except as provided in Section 7597, a public employee or other person may smoke in any outdoor area of a public building unless otherwise prohibited by state law or local ordinance and a sign describing the prohibition is posted by the state, county, or city agency or other appropriate entity.