Some firms have begun selling building owners and companies untested devices designed to detect anthrax and other biological agents, but city officials are worried that these will generate false alarms; in San Francisco city officials estimate that responding to a false alarm generated by a biological agent detector could cost as much as $700,000; legislation has been introduced to regulate these devices; the bill would require those who have biological agent detectors to pay an annual fee and owners would also be fined as much as $10,000 for false alarms; if passed, owners would have ninety days to register with the city