Goldman and partner Michael Koehn

Goldman and partner Michael Koehn enjoy a Volcano vaporizer --- a desktop unit that fills a bag with cannabis vapor. Vaporizers cut out the carcinogens associated with smoking cannabis. PHOTO: Michael Short for San Francisco Chronicle

Goldman and partner Michael Koehn enjoy a Volcano vaporizer — a desktop unit that fills a bag with cannabis vapor. Vaporizers cut out the carcinogens associated with smoking cannabis. PHOTO: Michael Short for San Francisco Chronicle